Lab Safety Handbook - St. Louis Public Schools

Lab Safety Handbook

Grades 6–8

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CONTENTS

Lab Safety Handbook

Safety in the Lab ............................................................................................ 1

Safety in the Field ......................................................................................... 3

Safety and Engineering ................................................................................ 4

Personal Protective Equipment ................................................................... 7

Safety with Glassware .................................................................................. 8

Safety with Chemicals ................................................................................ 10

Safety with Animals and Microbes ........................................................... 11

Safety with Physical Hazards .................................................................... 12

Safety Symbols ............................................................................................ 15

Safety Contract ............................................................................................ 16

Lab Techniques ............................................................................................ 17

The Metric System and SI Units ................................................................ 24

Measuring in the Lab .................................................................................. 26

Using a Microscope ...................................................................................... 35

Designing Safe Labs .................................................................................... 37

Answer Key .................................................................................................. 41

© Houghton Mifflin Harcourt Publishing Company

Grades 6–8Lab Safety Handbook iii

Rules for Working in the Laboratory

In the laboratory, you are responsible for your own safety and the safety of others. You can help prevent accidents in the lab by following these rules:

1. Always wear a lab apron and safety goggles. Wear these safety devices whenever you are in the lab, not just when you are working on an experiment.

2. No contact lenses in the lab. Contact lenses should not be worn during any investigations in which you are using chemicals (even if you are wearing goggles). In the event of an accident, chemicals can get behind contact lenses and cause serious damage before the lenses can be removed. If your doctor requires that you wear contact lenses instead of glasses, you should wear eye-cup safety goggles in the lab. Ask your doctor or your teacher how to use this very important and special piece of eye protection.

3. Personal apparel should be appropriate for laboratory work. On lab days, avoid wearing long necklaces, dangling bracelets, bulky jewelry, and bulky or loose-fitting clothing. Long hair should be tied back. Loose, flopping, or dangling items may get caught in moving parts, accidentally contact electrical connections, or interfere with the investigation in some potentially hazardous manner. In addition, chemical fumes may react with some jewelry, such as pearls, and ruin them. Cotton clothing is preferable to wool, nylon, or polyesters. Wear shoes that will protect your feet from chemical spills and falling objects—no open-toed shoes or sandals and no shoes with woven leather straps.

4. NEVER work alone in the laboratory. Work in the lab only while supervised by your teacher. Do not leave equipment unattended while it is in operation.

5. Only books and notebooks needed for the activity should be in the lab. Keep other books, backpacks, purses, phones and electronic devices, and similar items in your desk, locker, or designated storage area.

6. Read the entire activity before entering the lab. Your teacher will review any applicable safety precautions before you begin the lab activity. If you are not sure of something, ask your teacher about it.

7. Always heed safety symbols and cautions. The instructions for the experiments, user guides for laboratory equipment, and other materials in the lab will contain important information about safety. Always follow these safety guidelines, and always heed cautions given verbally by your teacher. They are provided for your safety.

8. Know fire safety procedures. Know the proper fire drill procedures and the locations of fire exits and emergency equipment. Make sure you know the procedures to follow in case of a fire or other emergency.

9. If your clothing catches on fire, do not run: WALK to the safety shower, stand under the showerhead, and turn the water on. Call for your teacher while you do this.

LAB SAFETY HANDBOOK

Safety in the Lab


Grades 6–8Lab Safety Handbook 1

10. Report all accidents to the teacher IMMEDIATELY. Even if an accident seems minor, make sure you tell your teacher about it right away. In addition, if you get a headache or feel ill or dizzy, tell your teacher immediately.

11. Report all spills to your teacher immediately. Rather than cleaning a spill yourself, call your teacher first. Your teacher will tell you if it is safe for you to clean up the spill and will give you instructions for doing so. If it is not safe for you to clean up the spill, your teacher will know how the spill should be cleaned up safely.

12. Get your teacher’s approval before conducting your own investigations. If a lab directs you to design your own experiments, your teacher must approve your procedure BEFORE you begin work.

13. DO NOT perform unauthorized experiments. Do not use equipment or apparatus in a manner for which they were not intended. Use only materials and equipment listed in the activity equipment list or authorized by your teacher. Steps in a procedure should only be performed as described in the lab manual or as approved by your teacher.

14. Stay alert while in the lab, and proceed with caution. Be aware of others near you or your equipment when you are working in the lab. If you are not sure of how to proceed, ask your teacher for help.

15. Horseplay in the lab is very dangerous. Laboratory equipment and apparatus are not toys; never play in the lab or use lab time or equipment for anything other than their intended purpose.

16. NEVER eat or drink in the lab. Food, beverages, and chewing gum are NEVER permitted in the laboratory. Do not use laboratory glassware or other equipment for food or drinks.

17. NEVER taste chemicals. Do not touch chemicals or allow them to contact areas of bare skin.

18. Use extreme caution when working with hot plates, burners, or other heating devices. Keep your head, hands, hair, and clothing away from the flame or heating device, and turn the devices off when they are not in use. Remember that metal surfaces connected to the heated area will become hot by conduction. Gas burners should be lit only with a spark lighter. Make sure all heating devices and gas valves are turned off before leaving the laboratory. Never leave a hot plate or other heating device unattended when it is in use. Remember that many metal, ceramic, and glass items do not always look hot when they are heated. Allow all items to cool before storing them.

19. Exercise caution when working with electrical equipment. Do not use electrical equipment that has frayed or twisted wires. Make sure your hands are dry before you use electrical equipment. Do not let electrical cords dangle from workstations; dangling cords can cause tripping or electrical shocks.

20. Keep work areas and apparatus clean and neat. Always clean up any clutter made during the course of lab work, rearrange apparatus in an orderly manner, and report any damaged or missing items to your teacher.

21. Wash your hands. Always thoroughly wash your hands with soap and water at the conclusion of each investigation.



Rules for Doing Fieldwork

Activities conducted outdoors or away from the laboratory require some advance planning to ensure a safe environment. The following general guidelines should be followed for fieldwork:

1. Know your mission. The goal of the field trip will be determined in advance. Be sure to have your permission slip approved before the trip, and check to make sure that you are dressed appropriately and have all necessary supplies for the day’s activity.

2. Find out about on-site hazards before setting out. Determine whether poisonous plants or dangerous animals are likely to be present where you are going. Know how to identify these hazards. Find out about other hazards, such as steep or slippery terrain, traffic, or human activity in the area.

3. Wear protective clothing. Dress in a manner that will keep you warm, comfortable, and dry. Determine in advance whether you will need sunglasses, a hat, gloves, boots, or rain gear to suit the terrain and local weather conditions. Your teacher will let you know whether you need sunscreen, insect repellant, or a flashlight.

4. NEVER approach or touch wild animals. If you see a threatening animal or an animal that seems injured or is behaving strangely, call your teacher immediately. Avoid any living thing that may sting, bite, scratch, or otherwise cause injury.

5. Do not touch wild plants or pick wildflowers unless your teacher specifically instructs you to do so. Many wild plants can be irritating or toxic. In some environments, plants may be protected, and picking them may be illegal. Never taste any wild plant.

6. Do not wander away from others. Travel with a partner at all times. Stay within specified areas, and make sure you stay within eyesight or earshot of your group in case you run into trouble.

7. Report all hazards or accidents to your teacher immediately. Even if the incident seems unimportant, let your teacher know what happened.

8. Maintain the safety of the environment. Be aware of the impact of your activities. Do not interfere with structures, plants, or animals, and do not remove anything from the field site without your teacher’s permission. Stay on trails, when possible, to avoid trampling delicate vegetation. Never leave garbage behind at a field site. Leave natural areas as you found them.

LAB SAFETY HANDBOOK

Safety in the Field



Safety and the Engineering Design Process

At every step in the engineering design process, it is important to keep safety in mind. Often, the problem or need that you are addressing will involve safety issues. Proposed solutions should always be evaluated for safety, and safety is an important consideration when building and testing a model or a prototype. Using these guidelines will help you identify and avoid safety issues:

1. Identify safety problems and needs. Consider safety issues when you are defining the problem or need your solution will address. Evaluate all proposed solutions for any safety issues, and move forward only with solutions that can be developed, tested, and implemented safely.

2. Develop and build a model. Once you have identified the best solutions for testing, you will develop a model. Models can be used to conduct testing that would be too expensive or dangerous. They can also be used to help you identify and solve safety issues with your design. Identify any safety hazards involved in developing your model, and present your plan to your teacher for approval. Follow appropriate safety guidelines as you build your model.

3. Test the model. Before testing your model, develop a plan that identifies the tests you will conduct and the data you will collect. Identify safety risks involved in your test plans, and make sure you implement appropriate safety procedures. Before conducting tests, present your plan to your teacher for approval.

4. Redefine the problem to clarify the most important criteria, including safety issues. Use the results from testing your models to help you clarify the design problem you are trying to solve. Pay special attention to safety issues your solution is designed to address. Also identify any safety hazards revealed by your tests, and make a plan to correct them so that your engineered solution is safe to build and implement.

5. Consider tradeoffs. Safety must always be a primary concern when evaluating how well your solution meets the constraints and criteria of the design problem. However, there are other practical considerations that may require engineers to make tradeoffs. For example, if the safest version of a device is too expensive or difficult to use, customers may not be able or willing to use it. However, if the only practical or cost-effective solution is unsafe, it must be rejected and new solutions must be developed.

6. Build a prototype. Once you have identified the best solution, tested the model, and made necessary tradeoffs, you will need to build and test a prototype. At this point, you may be working with power tools, hazardous chemicals, or other materials and processes that present their own safety concerns. Develop a plan that includes specific information about safety issues you might face and how you plan to address them. Always have your teacher approve your plan before you begin, and follow all necessary safety procedures. If you have a question about how to use equipment, stop working and ask for help. When your prototype is complete, assess it for safety before conducting your tests.

LAB SAFETY HANDBOOK

Safety and Engineering



7. Test the prototype. At this stage, it is very important to identify and address any remaining safety concerns. If there are concerns with whether your design is safe to produce or use, your tests must address these issues. Develop a plan that identifies the tests you will conduct. Your plan should explain how your tests will address safety concerns with your design, as well as how you will make sure your tests are conducted safely. Before conducting any tests, present your plan to your teacher for approval.

8. Refine the solution based on the results of the tests. As you perform iterative testing on your prototype, make sure you evaluate every change for safety. Once your final design is approved, you will be able to document any remaining safety issues and plan how to safely implement the solution.



Conducting Safe Investigations

Answer the following questions to check your safety smarts.

1. When you get to your lab station to start your lab, you notice a small puddle of clear liquid on the countertop. What is the best way to handle this situation?

A. Grab a paper towel and wipe up the spill; it is probably just water.

B. Report the spill to your teacher, who will tell you what to do.

C. Dip a finger into the liquid and taste it. If it has a taste, tell your teacher; otherwise, just wipe it up with a paper towel.

D. Ignore it; you can save yourself the effort if you just clean it up at the end of the lab when you are cleaning your lab station.

2. You and your lab partner have scheduled time in the lab to conduct an investigation. Your teacher has already approved your plan. When you get to the lab, your teacher is not there, but a note on the board says “Back in 10 minutes.” What should you do?

A. Set up your lab station and then eat a snack in the lab while you wait.

B. Go ahead and start working since your plan is already approved.

C. Put everything away except your lab procedure and notebook. Spend the time rereading your procedure and preparing your data tables.

D. Spend the time investigating the equipment in the room and testing the safety equipment, such as the safety shower and eyewash station.

3. Your class is going on a field trip to study trees and plants in a nearby forest. Later that day, you will be working in the lab to examine the specimens you collect. Describe what you should wear to be as safe as possible in the field and in the lab.

__________________________________________________________

__________________________________________________________

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4. Read the safety scenario described below. In the space provided, explain how the situation could have been prevented, and then describe the appropriate response once the problem has occurred.

Safety Scenario Prevention Response

A student who is working with unknown solutions pushes up her goggles to wipe sweat out of her eyes. Her eyes begin to burn and water.

LAB SAFETY HANDBOOK

Safety Check



Minimize Your Exposure to Hazards

Workers in many industries are required to use personal protective equipment (PPE) to protect themselves from hazards associated with their work and working environment. Scientists, engineers, and technicians often work with materials and processes that may be hazardous or have unexpected results.

Safety goggles should be worn whenever you are working in the laboratory. Wear only safety goggles provided by your teacher; laboratory goggles must meet certain safety standards to be safe and effective. Goggles protect your eyes from many laboratory hazards, such as chemical splashes, projectiles, fumes, and unexpected events. They also prevent you from rubbing your eyes.

Contact lenses should not be worn in the laboratory. If you must wear contact lenses, you should wear special eye-cup safety goggles that provide additional protection.

Face shields should be used in combination with safety goggles when working with certain hazardous substances. Always wear a face shield when instructed by your teacher, and do not remove it until instructed to do so.

An eyewash station delivers a gentle flow of water to both eyes in the case of eye injury or irritation. Such problems can be caused by chemical splashes, fumes, or airborne particles. If you experience any of these issues, go immediately to the eyewash station while calling to your teacher. Use the eyewash station for at least 15 minutes. Before you work in the laboratory, make sure you know the location of the eyewash station and how to use it.

A safety shower should be used in the event of a fire or chemical splash that cannot be rinsed off. If your clothing or hair catch fire, walk to the safety shower while calling to your teacher. Do not run; this may fan the flames and cause them to spread more quickly. Operate the shower to put out the flames. If your skin is irritated by a chemical spill that cannot be rinsed off in the sink, you should also use the safety shower to wash the chemical off your skin. Before you work in the laboratory, make sure you know the location of the safety shower and how to operate it.

Gloves should be worn to protect your hands when handling organisms, certain chemicals, or hazardous materials. In the lab, always keep your hands away from your eyes and mouth, whether you are wearing gloves or not.

An apron should be worn in the laboratory, particularly if you are working with chemicals other than water, using an open flame, or operating machinery. Lab aprons should be rubber-coated cloth or vinyl in order to protect your skin and clothing from splashes, spills, or broken glass.

LAB SAFETY HANDBOOK

Personal Protective Equipment



Handling Glassware Safely

You have probably noticed that a lot of laboratory equipment—such as test tubes, beakers, and flasks—is made out of glass. Despite being breakable, glass offers many benefits in the laboratory: It allows you to see the contents of different containers, it can be heated and cooled, and it does not react with most chemicals. Learn how to select the right glassware, use it properly, and clean it up safely if glassware breaks.

1. Inspect glassware before use. Do not use glassware that is chipped or cracked; it may break or shatter during use. If you find chipped or cracked glassware, tell your teacher.

2. Select the right glassware for heating and cooling. If you are going to be heating a substance in a glass container, make sure to use only borosilicate glass. Your teacher will show you the right glassware to use. This type of glass can be heated more safely than other kinds of glass, which are more likely to crack or shatter due to temperature changes.

3. Heat glassware safely. Even borosilicate glass will break if it is subjected to sudden changes in temperature. Always heat glassware slowly, and avoid conditions that will cause hot glass to cool quickly. Do not heat glassware in drafty areas, and never place hot glassware on cold or damp surfaces. Do not touch glassware that has been heated until it has had time to cool.

4. Never heat volumetric glassware. Some glassware is made specifically to allow precise measurements of volume. This type of glassware cannot be heated safely. The most common examples of volumetric glassware are graduated cylinders, volumetric flasks, burettes, and pipettes. Other examples of glassware that should not be heated are jars, funnels, and watch glasses. If you are not sure whether a piece of glassware can be heated, check with your teacher.

5. Handle test tubes safely. Test tubes are round on the bottom and cannot stand up by themselves. Always place test tubes in a rack to keep them from rolling off the table and breaking.

6. Heat test tubes safely. Place the test tube in a test-tube holder before you heat it. Hold the test tube at an angle above the flame. Position the tube so that the flame is directly under the liquid in the tube. Make sure the open end of the test tube is pointed away from people. Move the test tube gently above the flame so heat does not build up in one spot.

7. Heat beakers and flasks using a ring stand and ceramic screen. Support the container that is being heated on an iron ring above the burner. Use a wire screen that has a ceramic center to disperse the flame and distribute heat evenly. Adjust the flame to produce gradual heating of the beaker or flask; rapid heating may result in vigorous boiling and splashing. The flame should never touch the bottom of the container.

LAB SAFETY HANDBOOK

Safety with Glassware



8. Support crucibles when heating. If the laboratory procedure calls for you to use a crucible, make sure you follow the instructions precisely. Clay triangles are used to support crucibles for heating. Make sure the triangle is the correct size to support the crucible you want to use. Do not use triangles that have broken or crumbling clay pipes.

9. Cover the crucible safely. Always leave the lid on the crucible slightly open to permit vapors to escape. Position the lid so that the opening is not directed toward you or another person.

10. Alert your teacher if glassware breaks. Your teacher will tell you the best way to clean up the broken glass. Do not leave the accident unattended; if you are hurt, or if you need to step away from the area to find your teacher, ask another student to stay there and keep other people away from the mess until your teacher can come and direct the cleanup.

11. Follow cleaning instructions. When you are cleaning up your work area, follow your teacher’s directions for washing glassware. Take turns using the sink or washing station, and be careful when handling wet glassware.



Handling Chemicals Safely

The safe use of chemicals in the laboratory requires you to be respectful of and aware of chemical hazards. Follow your teacher’s instructions for how to handle, use, and dispose of chemicals in the lab.

1. Wear protection in the laboratory. When chemicals are in use, always wear eye and face protection, hand protection, and a lab apron. Follow safety guidelines for clothing, shoes, hair, and jewelry.

2. Know the location of safety equipment, and know how to use it. If a chemical gets on your skin, on your clothing, or in your eyes, rinse it immediately (shower, faucet, or eyewash station) and alert your teacher.

3. Check labels carefully. Make sure you know what chemicals you are using. Check the labels on the chemicals your teacher provides, and make sure to label test tubes or beakers before you put chemicals into them. Ask your teacher to show you the Safety Data Sheet (SDS) for the chemicals you will be using in the lab. Make sure you know how to read the information on the SDS.

4. Avoid contamination. Take only the amount of chemical you need for the investigation. If you accidentally get too much, ask your teacher how to dispose of the excess. Do not return unused chemicals to the storage container; this can cause contamination.

5. Tell your teacher about spills immediately. Do not clean up any spilled chemicals yourself unless your teacher directs you to do so.

6. Handle materials that emit vapors or gases in a well-ventilated area. Follow your teacher’s instructions and handle chemicals as directed. Do not taste chemicals or inhale fumes or vapors. If your teacher directs you to smell any substance, hold the substance away from your face and use your hand to gently waft the scent toward your nose. If you experience any irritation, let your teacher know right away.

7. Dispose of all materials as directed by your teacher. Your teacher will tell you how to dispose of leftover chemicals, the products of chemical reactions, and other materials. Some chemicals can be washed down the drain, but others require special handling.

LAB SAFETY HANDBOOK

Safety with Chemicals



Working Safely with Animals and Microbes

The study of animals has led to many scientific discoveries. Scientists may study live animals in the field or in the lab. In addition, preserved specimens can be useful for observations or dissection. Whenever you are working with animals or microbes, use caution and follow all safety instructions.

1. Wash your hands before and after. Before handling a live animal, a preserved specimen, or microorganisms, wash your hands thoroughly with soap and water. While you are working, keep your hands away from your eyes and mouth. Wash your hands thoroughly when you are finished. If you are working with more than one animal or specimen, wash your hands in between.

2. Wear protection. Wear gloves when handling animals, preserved specimens, or microorganisms. If you are performing a dissection on a preserved specimen, wear goggles, gloves, and an apron.

3. Treat animals with respect. Do not approach or touch live animals without your teacher’s permission. Never touch wild animals, even if they appear tame. In the field, observe animals from a safe distance, and let your teacher know if an animal is acting strangely. When working with live animals in the lab, touch animals only when necessary. Do not perform investigations that may cause stress, suffering, or pain. Never hurt an animal.

4. Follow safety procedures. Specimens for dissection should be properly mounted and supported. Before you make any cuts, make sure you plan exactly what incision to make. Never cut a specimen while holding it in your hands. Do not open containers of live microorganisms unless you are directed to do so. Immediately alert your teacher to any spills.

5. Keep work areas clean and organized. Whether you are working with live animals or preserved specimens, keep your work area clean and your tools organized. Follow your teacher’s instructions for cleaning, disposal, or storage of supplies.

LAB SAFETY HANDBOOK

Safety with Animals and Microbes



Working Safely with Physical Hazards

Physical hazards are commonly found in the laboratory, but they often get overlooked. However, it is important to be aware of the potential for injuries and accidents when working with physical hazards. This is especially true in a crowded and busy room. Always follow your teacher’s instructions, and pay attention to these common safety hazards.

1. Moving objects can be dangerous. Any time moving objects are present, whether they are balls, cars, cylinders, or hoops, care must be taken to contain these objects. A marble rolling on the floor may not seem dangerous, but in a busy room it could cause a serious accident if someone stepped on it while walking. Projectiles of any kind should be launched only when the area is clear. Objects should never be launched, rolled, or pushed toward people who are not prepared.

2. Projectiles can be dangerous. Follow these tips to prevent accidents. Wear safety goggles when working with projectiles. Use a box to catch the projectile so that it doesn’t bounce or roll away from your work area. If possible, use a softer projectile, especially in a crowded room. Lay out firing paths that do not overlap. Do not lean into or walk across projectile paths. Announce when you are going to launch a projectile so that others can move out of the way. Do not launch until you know the path is clear.

3. Spinning objects can be dangerous. Objects that are attached to apparatus may become projectiles if they break away from the apparatus. Examples include anything that has a hanging mass and may be spun. Wear goggles when working with spinning objects. Always check the apparatus before you begin; make sure all parts are firmly attached and in good condition. Do not use apparatus that has frayed strings, cracked handles, or other problems. Use the lightest spinning objects possible, and use the lowest speeds that will provide good results. Work in a clear area away from other people.

4. Falling objects can be dangerous. Many investigations involve falling objects. Objects may also fall and create a hazard during the course of any investigation. When you are working with falling objects, follow the same precautions as for projectiles. In the laboratory, pay attention to your equipment, and take care to prevent objects from falling. Do not place glassware or other items too close to the edge of the table, and make sure objects that can roll or scatter are contained or securely clamped.

5. Always make safety a priority. Whenever you are working with lab equipment, pay attention to possible safety hazards and take steps to address them. Clamps, rods, rulers, and other equipment should be set up so that they are not at eye level and do not protrude into walkways. Keep walkways clear of furniture, equipment, backpacks, or other items. Do not stand on chairs or use furniture or fixtures for anything but their intended purpose. If your laboratory setup is difficult for you to use, ask your teacher for help making adjustments.

LAB SAFETY HANDBOOK

Safety with Physical Hazards



LAB SAFETY HANDBOOK

Safety Check

Working Safely in the Lab


1. You are going into the lab to do an investigation involving heating different substances. What personal protection equipment should you wear?

A. Gloves and goggles

B. Gloves, goggles, and an apron

C. None; just be careful when working with chemicals

D. Face shield and apron

2. Which of the following situations present avoidable safety risks when working with glassware? Choose all that apply.

A. Six students are crowded around one sink to wash glassware.

B. When setting up lab equipment, a student lays six test tubes on the table and then goes to get a test-tube stand.

C. A student is wearing goggles and using a test-tube clamp to hold a borosilicate test tube above the flame on a burner.

D. A student heats water in a beaker and then places the beaker on a wet paper towel.

3. Your class is studying motion by rolling marbles down a ramp and measuring how long it takes different marbles to reach the floor. Identify a safety issue associated with this activity.

__________________________________________________________

__________________________________________________________

__________________________________________________________

4. Consider the safety issue you identified in Question 3. Describe what precautions you would take to prevent accidents in the lab.

__________________________________________________________

__________________________________________________________

__________________________________________________________

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A student is pouring samples of different clear solutions into test tubes held in a test-tube rack. The student carries the test-tube rack back to the lab station and starts making test-tube labels but cannot remember which solution is which.



Safety SymbolsSafety is the priority in the science classroom. In all of the activities in this textbook, safety symbols are used to alert you to materials, procedures, or situations that could be potentially hazardous if the safety guidelines are not followed. Learn what you need to do when you see these icons, and read all lab procedures before coming to the lab so you are prepared. Always ask your teacher if you have questions.

ANIMAL SAFETY Never injure an animal. Follow your teacher’s instructions for handling specific animals or preserved specimens. Wash your hands with soap and water when finished handling animals or preserved specimens.

APRON Wear an apron when using any substance that could cause harm if spilled on you. Stand whenever possible to avoid spilling in your lap.

BREAKAGE Use caution when handling items that may break, such as glassware and thermometers. Always store test tubes in a test-tube rack.

CHEMICAL SAFETY Always wear goggles when working with chemicals. Stand whenever possible when working with chemicals to avoid spilling on your lap. Tell your teacher immediately if you spill chemicals on yourself, the table, or the floor. Never taste any substance or chemical in the lab. Always wash your hands after working with chemicals.

DISPOSAL Follow your teacher’s instructions for disposing of all waste materials, including chemicals, specimens, or broken glass.

ELECTRICAL SAFETY Keep electrical cords away from water to avoid shock. Do not use cords with frayed edges. Unplug all equipment when done.

FIRE SAFETY Put on safety goggles before lighting flames. Remove loose clothing and tie back hair. Never leave a lit object unattended. Extinguish flames as soon as you finish heating.

FUMES Always work in a well-ventilated area. Bring fumes up to your nose by wafting with your fingers instead of sniffing.

GLOVES Always wear gloves to protect your skin from possible injury when working with substances that may be harmful or when working with animals.

HAND WASHING Wash your hands with soap and water after working with soil, chemicals, animals, or preserved specimens.

HEATING SAFETY Wear goggles and never leave any substance while it is being heated. Use tongs, hot pads, or test-tube holders to hold hot objects. Point any materials being heated away from you and others. Place hot objects such as test tubes in test-tube racks while cooling. Always wear gloves such as oven mitts when handling larger hot materials.

PLANT SAFETY Do not eat any part of a plant. Do not pick any wild plants unless your teacher instructs you to do so. Wash your hands after handling any plant.

POISON Never touch, taste, or inhale chemicals. Most chemicals are toxic in high concentrations. Wear goggles and wash your hands.

SAFETY GOGGLES Always wear safety goggles when working with chemicals, heating any substance, or using a sharp object or any material that could fly up and injure you or others.

SHARP OBJECTS Use scissors, knives, or razor tools with care. Wear goggles when cutting something with scalpels, knives, or razor tools. Always cut away from yourself.

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The following safety symbols will appear in the instructions for labs and activities to alert you to materials, procedures, or situations that could be potentially hazardous if the safety guidelines are not followed. Learn what you need to do when you see these icons, and read all lab procedures before coming to the lab so you are prepared. Always ask your teacher if you have questions. Remember that no matter what safety symbols you see within each lab, all safety rules should be followed at all times.

LAB SAFETY HANDBOOK

Safety Symbols



Safety Contract

I, _____________________________________________ (student’s name), have read and understand all the lab safety rules and guidelines I have been given both orally and in writing. I understand and agree to follow all of these safety rules and guidelines and all others that are stated at any time during the school year. At all times, I will conduct myself in a responsible manner that will make sure that everyone—including myself, fellow students, teachers, and bystanders—is safe in the lab, classroom, or anywhere activities are conducted. I acknowledge that if I violate this safety contract, I may face disciplinary measures at the discretion of my teacher and other school officials.

______________________________________________Student’s signature

______________________________________________Date

I, ______________________________________________ (parent/guardian’s name), have read and understand the lab safety rules and guidelines. I understand that my student will need to adhere to these rules whenever he/she is participating in science activities, whether in the lab, in the classroom, on school property, or on field trips. I agree to instruct him/her to follow all instructions from the teacher at all times. I understand my student will be subject to disciplinary action for failure to comply with any safety rules or guidelines.

______________________________________________Parent/guardian’s signature

______________________________________________Date

LAB SAFETY HANDBOOK

Safety Contract



How to Decant and Transfer Liquids

When you want to transfer the liquid from a container that also contains a solid material, you must be careful not to include the solid material in the transfer. The transfer of a liquid from a container that contains both liquid and solid materials is called decantation.

Use one of the methods shown to separate a liquid from solid material.

Allow the solid material to settle to the bottom of the container. Carefully pick up the container and slowly tilt it to allow the liquid to pour out into another container. If done properly, almost all the liquid can be transferred to another container.

You can decant a liquid from a beaker by using a stirring rod. The rod should touch the wall of the receiving container. Hold the stirring rod against the lip of the beaker containing the liquid. As you pour, the liquid will run down the rod and fall into the beaker resting below. When you use this method, the liquid will not run down the side of the beaker from which you are pouring because the stirring rod helps control the flow of the liquid and reduces the risk of splashing.

In some situations, you can perform this technique with one hand, as follows:

• Place the stirring rod across a beaker so that most of it extends past the lip of the beaker.

• Grasp the beaker in one hand while using one finger to hold the stirring rod against the beaker. Your finger needs to hold the stirring rod firmly but not hard enough to break the rod.

• Tilt the beaker to pour out the liquid.• If the receiving container has a very small opening, use a small funnel. Pour liquid

slowly into the funnel so that it does not overflow.

LAB SAFETY HANDBOOK

Lab Techniques



How to Heat Substances and Evaporate Solutions

When you are heating substances in the lab, you must be sure to use the right glassware. Always verify that your apparatus is set up correctly and securely before placing glassware containing chemical substances.

Use care in selecting glassware for high-temperature heating. The glassware should be heat resistant.

When heating glassware with a gas flame, use a wire gauze with a ceramic center to protect glassware from direct contact with the flame. Wire gauzes can withstand extremely high temperatures and will help protect glassware from breaking.

In some experiments, you will be required to heat a substance to high temperatures in a porcelain crucible. Use a clay triangle of the right size to support the crucible, and keep the lid tilted at an angle so that vapors or fumes are directed away from people.

LAB SAFETY HANDBOOK

Lab Techniques

A third method is to use a porcelain evaporating dish with a watch glass cover to prevent spattering. Keep the flame low to control the rate of evaporation and keep spattering to a minimum.



Glassware, porcelain, and iron rings that have been heated may look cool after they are removed from a heat source, but these items can still burn your skin even after several minutes of cooling. Use tongs, test-tube holders, or heat-resistant mitts and pads whenever you handle items that have been heated.

You can test the temperature of beakers, ring stands, wire gauzes, or other items that have been heated by holding the back of your hand close to their surfaces before touching them. You will be able to feel whether the items are still hot. Always allow plenty of time for equipment to cool before handling.



How to Pour Liquid from a Reagent Bottle

In the laboratory, you often will need to measure out a specific amount of liquid from a labeled bottle called a reagent bottle. Learn how to pour liquid from a reagent bottle without waste, contamination, or spills.

Read the label at least three times before using the contents of a reagent bottle.

Never lay the stopper of a reagent bottle on the lab table. Hold the stopper so that your hand does not come in contact with the side of the stopper that goes into the bottle.

When pouring a caustic or corrosive liquid into a beaker, use a stirring rod to prevent drips and spills. Hold the stirring rod against the lip of the reagent bottle. Estimate the amount of liquid you need, and pour this amount along the rod into the beaker as shown.

LAB SA FETY HANDBOOK

Lab Techniques

Use extra caution when handling a bottle of acid. Remember the following important rules: Never add water to any concentrated acid, particularly sulfuric acid, because the mixture can splash and will generate a lot of energy as heat. To dilute any acid, add the acid to water in small quantities while stirring slowly. Remember the “triple A rule”—Always Add Acid to water.

Replace the stopper and examine the outside of the reagent bottle for any liquid that has dripped down the bottle or spilled on the countertop. Your teacher will show you the proper procedures for cleaning up a chemical spill.

At the end of your experiment, your teacher will tell you how to dispose of any excess chemicals.



How to Heat Material in a Test Tube

The rounded bottom and narrow shape of a test tube make it an efficient container for heating material in the lab, but test tubes also present safety challenges. Learn how to use a test tube to heat material safely.

1. Check to make sure that the test tube is heat resistant.

2. Always use a test-tube holder or clamp when heating a test tube.

3. Never point a heated test tube at anyone, because the liquid may splash out of the test tube.

4. Never look down into the test tube while heating it.

5. Heat the test tube from the upper portions of the tube downward, and continuously move the test tube, as shown. Do not heat any one spot on the test tube. Otherwise, pressure may cause the bottom of the tube to blow out.

LAB SAFETY HANDBOOK

Lab Techniques

How to Use a Mortar and Pestle

In order to break up a solid substance into smaller pieces or into a powder, you will need to use a mortar and pestle. The mortar is the container that holds the substance, and the pestle is the tool used to mash and grind it.

1. A mortar and pestle should be used to grind only one substance at a time.

2. Never use a mortar and pestle to mix different substances.

3. Place the substance to be broken up into the mortar.

4. Pound the substance firmly but gently with the pestle. Then grind to pulverize.

5. Remove the powdered substance with a porcelain spoon.

6. Clean the mortar and pestle as directed by your teacher.



How to Detect Odors Safely

Odors can help you identify substances or detect a chemical change. Learn to detect odors safely so you are not inhaling hazardous fumes.

1. Hold the test tube away from your body, as shown.

2. Test for the odor of gases by wafting your hand over the test tube and cautiously sniffi ng the fumes.

3. Do not inhale any fumes directly.

4. Use a fume hood whenever poisonous or irritating fumes are present. Never waft and sniff poisonous or irritating fumes.



Working Safely in the Lab


1. Your lab partner has prepared two beakers of water and set them on the lab table. One beaker has ice-cold water, and the other has been heated to just below boiling. Your partner asks you to pour the cold water into a graduated cylinder, but you are not sure which is which. What is the best plan?

A. Touch the outside of both beakers with your bare finger to determine which beaker is cold and which is hot.

B. Hold the back of your hand near each beaker to feel which is hot and which is cold.

C. Dip a finger into each beaker.

D. Pour out both beakers and start over.

2. At the beginning of a chemistry investigation, your teacher reminds you to follow the “triple A rule.” What does this mean?

A. When you are not sure what the instructions mean, you should always ask for clarification before starting to work in the lab.

B. Students who pass the safety test can work in the lab without supervision, because they are always already approved.

C. To dilute an acid with water, you should always add acid to water.

D. To heat a liquid in a test tube, always allow airspace at the top.

3. Describe how to use a stirring rod when pouring liquids from one container to another.

__________________________________________________________

__________________________________________________________

__________________________________________________________



A student is heating a substance in a test tube by holding the test tube so that its bottom is touching the top of the flame. Suddenly, the test tube cracks.

LAB SAFETY HANDBOOK

Safety Check



The Metric System and SI Units

Scientists use International System (SI) units to measure time, distance, volume, mass, electric current, and temperature. The International System is based on powers of 10 and the metric system of measurement.

LAB SAFETY HANDBOOK


SI Base Units

Symbol Name Quantity

A ampere current

K kelvin temperature

kg kilogram mass

L liter volume

m meter length

s second time

SI Prefixes

Symbol Prefix Power of 10 Scientific Notation

f femto– 0.001 or 1 ___________________ 1,000,000,000,000,000 10–15

p pico– 0.001 or 1 ________________ 1,000,000,000,000 10–12

n nano– 0.001 or 1 ____________ 1,000,000,000 10–9

μ micro– 0.000001 or 1 _________ 1,000,000 10–6

m milli– 0.001 or 1 _____ 1000 10–3

c centi– 0.01 or 1 ____ 100 10–2

d deci– 0.1 or 1 ___ 10 10–1

da deca– 10 101

h hecto– 100 102

k kilo– 1000 103

M mega– 1,000,000 106

G giga– 1,000,000,000 109

T tera– 1,000,000,000,000 1012

P peta– 1,000,000,000,000,000 1015



Change to a larger unit

Change to a smaller unit

÷1000

÷10

x10 x100

x1000 x1000

÷100

÷1000

milli- centi- deci- deca- hecto- kilo- unit (m, g, or L)

6_CFLAESE365770_1457Tfinal2-17-10LKell

Change to a larger unit by dividingChange to a smaller unit by multiplying

6_CFLAESE365770_1458Tfinal2-19-10LKell

mL x 1000 L

0.64 x 1000 = 640.

g ÷ 1000 kg

26.3 ÷ 1000 = 0.0263

ANSWER 0.64 L = 640 mL

Example

Change 0.64 liters to milliliters.

1. Decide whether to multiply or divide.

2. Select the power of 10.

Example

Change 23.6 grams to kilograms.

1. Decide whether to multiply or divide.

2. Select the power of 10.

ANSWER 23.6 g = 0.0236 kg

Changing Metric Units

You can change from one unit to another in the metric system by multiplying or dividing by a power of 10.

LAB SAFETY HANDBOOK




Precision and Accuracy

When you do a scientific investigation or when you engineer a solution to a problem, it is important that your methods, observations, measurements, and data are both precise and accurate.

Precision

In science, precision is the exactness and consistency of measurements. For example, measurements made with a ruler that has both centimeter and millimeter markings would be more precise than measurements made with a ruler that has only centimeter markings. Another indicator of precision is the care taken to make sure that methods and observations are as exact and consistent as possible. Every time a particular experiment is done, the same procedure should be used. Precision is necessary because experiments are repeated several times and if the procedure changes, the results might change.

Example

Suppose you are measuring temperatures over a two-week period. Your precision will be greater if you measure each temperature at the same place, at the same time of day, and with the same thermometer than if you change any of these factors from one day to the next.

Accuracy

In science, it is possible to be precise but not accurate. Accuracy depends on the difference between a measurement and an actual value. The smaller the difference, the more accurate the measurement.

Example

Suppose you look at a stream and estimate that it is about 1 meter wide at a particular place. You decide to check your estimate by measuring the stream with a meter stick, and you determine that the stream is 1.32 meters wide. However, because it is difficult to measure the width of a stream with a meter stick, it turns out that your measurement was not very accurate. The stream is actually 1.14 meters wide. Therefore, even though your estimate of about 1 meter was less precise than your measurement, your estimate was actually more accurate.

LAB SAFETY HANDBOOK

Measuring in the Lab



meniscus

Read the volume at the bottom of the meniscus. The volume is 96 mL.

Measure the Volume of a Liquid with a Graduated Cylinder

• Be sure that the graduated cylinder is on a flat surface so that your measurement will be accurate.

• When reading the scale on a graduated cylinder, be sure to have your eyes at the level of the surface of the liquid.

• The surface of the liquid will be curved in the graduated cylinder. Read the volume of the liquid at the bottom of the curve, or meniscus.

• You can also use a graduated cylinder to find the volume of a solid object by measuring the increase in a liquid’s level after you add the object to the cylinder.

LAB SAFETY HANDBOOK




Not to scale

Measure Length with a Metric Ruler

1. To measure a flat object such as a leaf, lay a ruler flat on top of the leaf so that the 1-centimeter mark lines up with one end of the leaf. To measure an object that is not flat like a leaf, place the ruler next to the object. Make sure the ruler and the object do not move between the time you line them up and the time you take the measurement.

2. Look straight down on the ruler so that you can see exactly how the marks line up with the other end of the object.

3. Estimate the length by which the object extends beyond the nearest marking. For example, the leaf below extends about halfway between the 4.2-centimeter and 4.3-centimeter marks, so the apparent measurement is about 4.25 centimeters.

4. Remember to subtract 1 centimeter from your apparent measurement, because you started at the 1-centimeter mark on the ruler and not at the end. The leaf shown is about 3.25 centimeters long (4.25 cm – 1 cm = 3.25 cm).

LAB SAFETY HANDBOOK




pan

beams

smallest rider (3 g)

largest rider (300 g)

middle rider (90 g)

300 g position of largest rider 90 g position of middle rider + 3 g position of smallest rider

393 g mass of beaker and water

Triple Beam Balance

This type of balance has a pan and three beams with sliding masses, called riders. At one end of the beams is a pointer that indicates whether the mass on the pan is equal to the masses shown on the beams.

How to Measure the Mass of an Object

1. Make sure the balance is zeroed before measuring the mass of an object. The balance is zeroed if the pointer is at zero when nothing is on the pan and the riders are at their zero points. Use the adjustment knob at the base of the balance to zero it.

2. Place the object to be measured on the pan.

3. Move the riders one notch at a time away from the pan. Begin with the largest rider. If moving the largest rider one notch brings the pointer below zero, move the rider back one notch and begin measuring the mass of the object with the next smaller rider.

4. Change the positions of the riders until they balance the mass on the pan and the pointer is at zero. Then add the readings from the three beams to determine the mass of the object.

LAB SAFETY HANDBOOK




Record the mass of an object to the nearest

milligram (mg). The mass measured is

5.726 grams.

Electronic Balance

How to Measure the Mass of an Object

1. Be sure the balance is on a flat, stable surface.

2. Zero, or tare, the balance using the appropriate key. If you are measuring a specific quantity of a substance using a weigh boat or other container, place the weigh boat or container on the balance pan before zeroing the balance.

3. When the readout on the balance is steady and within a few thousandths of zero grams, place the object to be measured on the balance. If you are measuring out chemicals or other substances, wear gloves and use a clean spatula or similar tool to transfer the substance. Do not reach into containers or touch chemicals with your hands.

4. Record the mass of the object to the nearest milligram (1/1000 of 1 gram).

LAB SAFETY HANDBOOK




Record the weight of an

object to the nearest 0.5 N.

The weight measured is 1.5 N.

Spring Scale

Spring scales are tools that measure forces, such as weight, or the gravitational force exerted on an object. A spring scale indicates an object’s weight by measuring how far the spring stretches when an object is suspended from it. This type of scale is often used in grocery stores or to measure the weights of large loads of crops or industrial products.

How to Measure the Weight of an Object

• Be sure the spring scale is securely suspended and is not touching the ground, wall, or desk. The pointer should be at zero.

• Hang the object to be weighed from the hook at the free end of the spring scale. • When the object is still—not bouncing, swinging, or otherwise moving—read the

object’s weight to the nearest 0.5 N.

LAB SAFETY HANDBOOK




Report temperature to the nearest half degree. The temperature measured is 52.5 °C.

Thermometer

Many laboratory thermometers are the bulb type shown below. The sensing bulb of the thermometer is filled with a colored liquid (alcohol) that expands as it is heated. When the liquid expands, it moves up the stem of the thermometer through the capillary tube. Thermometers usually measure temperature in degrees Celsius (°C).

How to Measure the Temperature of a Substance

Caution: Do not hold the thermometer in your hand while measuring the temperature of a heated substance. Never use a thermometer to stir a solution. Always consult your teacher regarding proper laboratory techniques and safety rules when using a thermometer.

• Carefully lower the bulb of the thermometer into the substance. The stem of the thermometer may rest against the side of the container, but the bulb should never rest on the bottom. If the thermometer has an adjustable clip for the side of the container, use the clip to suspend the thermometer in the liquid.

• Watch the colored liquid as it rises in the thermometer’s capillary tube. When the liquid stops rising, note the whole-degree increment nearest the top of the liquid column.

• If your thermometer is marked in whole degrees, report temperature to the nearest half degree.

LAB SAFETY HANDBOOK




This probe measures the temperature of the substance in the beaker.

A device such as this computer is connected to the temperature probe. The program records temperature data and generates a graph of temperature change over time.

This motion detector uses ultrasonic waves to measure the acceleration of the toy car as it moves up and down the track.

Use a motion detector to gather information about an object’s velocity, position, or acceleration.

Introduction to Probeware

Probeware is a system of tools that offers a way to measure and analyze various physical properties, such as pressure, pH, temperature, or acceleration. Most probeware systems consist of a sensor, or probe, that is connected to a device such as a computer. As the sensor takes measurements, a computer program records the data. Users can then analyze data using tables, charts, or graphs. Some systems allow you to analyze more than one variable at a time.

Temperature Probe

LAB SAFETY HANDBOOK


Motion Detector



Use a pH probe to determine whether a substance is acidic, neutral, or basic.

pH probes measure the concentration of hydrogen ions in a liquid, such as the substance in the beaker shown here.

The tip of a pH probe is a thin glass membrane that should not be allowed to dry out. Store pH probes in the appropriate container and solution when you are finished with your investigation.

pH Probe



Body The body separates the lens in the eyepiece from the objective lenses below.

Eyepiece Objects are viewed through the eyepiece. The eyepiece contains a lens that commonly magnifies an image 10 times.

Nosepiece The nosepiece holds the objective lenses above the stage and rotates so that all lenses may be used.

Coarse Adjustment This knob is used to focus the image of an object when it is viewed through the low-power lens.

High-Power Objective Lens This is the largest lens on the nosepiece. It magnifies an image approximately 40 times.

Fine Adjustment This knob is used to focus the image of an object when it is viewed through the high-power lens.

Stage The stage supports the object being viewed.

Low-Power Objective Lens This is the smallest lens on the nosepiece. It magnifies images about 10 times.

Diaphragm The diaphragm is used to adjust the amount of light passing through the slide and into an objective lens.

Arm The arm supports the body above the stage. Always carry a microscope by the arm and base.

Mirror or Light Source Some microscopes use light that is reflected through the stage by a mirror. Other microscopes have their own light sources.

Stage Clip The stage clip holds a slide in place on the stage.

Base The base supports the microscope.

Introduction to Using a Microscope

Scientists use microscopes to see very small objects that cannot easily be seen with the eye alone. A microscope magnifies the image of an object so that small details may be observed. A microscope that you may use can magnify an object 400 times—that is, the object will appear 400 times larger than its actual size.

LAB SAFETY HANDBOOK

Using a Microscope





1. When using a metric ruler to measure length, why should you line up the end of the item with the 1-cm mark instead of against the end of the ruler?

A. Metric rulers are not very precise, so always round to the nearest 1 cm.

B. The end of the ruler might be damaged or worn down.

C. Subtracting 1 cm from your final measurement is more accurate.

D. Adding 1 cm to your final measurement is more accurate.

2. What laboratory equipment can you use to find the weight of an object?

A. motion detector

B. triple-beam balance

C. electronic balance

D. spring scale

3. Your classmate wants to use a probeware system with a temperature probe to take measurements as a beaker of ice is heated but is not sure if the probe is accurate. Describe how your classmate could figure out whether the temperature probe is giving accurate readings.

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________



A student uses an electronic balance to find the masses of different objects. After class, the student realizes that all the measurements include the mass of the weigh boat.

LAB SAFETY HANDBOOK

Safety Check



Designing, Conducting, and Reporting an Investigation

Scientists plan and conduct investigations to answer questions or test solutions to problems. Well-designed investigations can provide evidence to support explanations or to develop and test models and solutions to engineering problems.

Identifying a Question or Problem to Investigate

• Scientific investigations can help you answer questions about phenomena or scientific principles.

• Engineering investigations can help you to improve existing technology or processes or to compare different solutions to see which one provides the best solution to a problem.

• In both science and engineering investigations, the first step is to develop a well-defined question or problem statement.

Brainstorming Solutions or Developing a Hypothesis

• Once you have clearly stated the question you want to answer or the problem you want to solve, you can start brainstorming possible solutions or forming a hypothesis. Solutions should address the problem and meet the criteria and constraints for the problem you are trying to solve. A hypothesis is a tentative explanation for an expected result of a scientific investigation.

Identifying Variables to Test the Hypothesis or Compare Solutions

• The next step is to design an experiment to test the hypothesis or answer the question or to test and compare different solutions.

• In a controlled experiment, you can investigate how two factors are related by testing a control group and an experimental group. The two groups are the same, except that you will change and test a single factor in the experimental group while keeping that factor the same in the control group.

• A variable is any factor that can change. Constants are all of the variables that are kept the same in both the experimental group and the control group.

• The independent variable is the factor that is manipulated or changed in order to test the effect of the change on another variable. The dependent variable is the factor the investigator measures to gather data about the effect.

• For example, if you wanted to investigate whether adding fertilizer to pond water affects the amount of algae in the pond, the independent variable would be the amount of fertilizer in the water. The growth of the algae in the water is the dependent variable. It is the factor you will measure to gather data about the relationship. The constants would be the factors that you keep the same to make sure the results of your tests can be compared meaningfully. Some constants for this investigation would be the source of the pond water, the amount of water in each sample, the type of container the water is in, and the conditions (such as light and temperature) where the water is stored.

LAB SAFETY HANDBOOK

Designing Safe Labs



Plan and Write a Procedure

• Once you know the question you are trying to answer or the problem you are trying to solve and you have identified the constants and variables you will investigate, it is time to plan out the steps of your procedure.

• Write down all the steps you think you will need to follow to conduct your investigation. Start each step with a verb, or action word, and keep the steps short.

• Your plan should describe the tools you will need to gather data, how measurements and observations will be recorded, and how much data you need to collect to provide evidence that will meet the goals of your investigation.

• When you have all the steps written down, read through your procedure to make sure it is complete and logical. Make sure the steps are written in the order in which they will be done, and check to see if any steps are missing. For example, if you need to measure the volume or mass of the pond water to make sure your samples are the same size, include a step for making the measurements you will need.

• Make sure your procedure identifies and addresses any safety risks. Include information about the personal protective equipment you will use during the investigation.

• Your final procedure should be clear enough for someone else to use as instructions for repeating your experiment.

Plan and Write a Procedure

• Before you carry out your procedure, present it to your teacher for approval. • Once your procedure is approved, you can gather the tools and materials you will

need and begin to experiment and collect data. • Record both quantitative data (measurements) and qualitative data (observations) as

shown in the sample lab notebook.



Algal Growth and Fertilizer

Experimental Group Control Group

Date and Time Jar 1 with Fertilizer

(diameter of algal clump

in mm)

Jar 2 with Fertilizer


in mm)

Jar 1 without Fertilizer


in mm)



in mm)

Observations

5/3 4:00 p.m.

0 0 0 0 condensation in all containers

5/4 4:00 p.m.

0 3 0 0 tiny green blobs in Jar 2 with fertilizer

5/5 4:15 p.m.

4 5 0 3 green blobs in Jars 1 and 2 with fertilizer and Jar 2 without fertilizer

5/6 4:00 p.m.

5 6 0 4 water light green in Jar 2 with fertilizer

5/7 4:00 p.m.

8 10 0 6 water light green in Jars 1 and 2 with fertilizer and Jar 2 without fertilizer

5/8 3:30 p.m.

10 18 0 6 cover off of Jar 2 with fertilizer

5/9 3:30 p.m.

14 23 0 8 drew sketches of each container

Drawings of Samples Viewed Under Microscope on 5/9 at 100x







FPO

Algal Growth and Fertilizer

Diam

eter

of a

lgal

clu

mp

(mm

)

Date (month/day)

Algal Growth and Fertilizer25

20

15

10

5

0

5/3 5/4 5/5 5/6 5/7 5/8 5/9

6-8-A_CNLAESE589367_55Afinal3-15-10LKell

Experimental GroupJar 1 with fertilizerJar 2 with fertilizer

Control GroupJar 1 without fertilizerJar 2 without fertilizer

Analyze Data

• After you complete your investigation, you must analyze all of the data you have gathered. Tables, statistics, and graphs are often used in this step to organize and analyze both the qualitative and quantitative data. Sometimes qualitative data are best used to help explain the relationships you see in your quantitative data.

• Computer graphing software is useful for creating a graph from data you have collected. Most graphing software can make line graphs, circle graphs, or bar graphs from data that have been organized in a spreadsheet. Graphs are useful for understanding relationships in the data and for communicating the results of your experiment.

Draw Conclusions

• To draw conclusions from your investigation, fi rst write the results of your data analysis.

• Then compare your results with your hypothesis or with the criteria and constraints for the solution.

• Use your results to answer the following questions: Do your results support your hypothesis? Have you found a solution that satisfi es the criteria and constraints? What have you learned from your investigation?

• At this point, you may be fi nished with your investigation. Or you may have discovered that you have additional questions or that you need to refi ne and test your solution further. Follow these same guidelines to plan further investigations to answer new questions and to test new solutions.



Page 6

1. B

2. C

3. Sample answer: closed-toe shoes, long pants, and long sleeves. In the forest: a hat, sunscreen, jacket, gloves; in the lab: goggles, apron, gloves

4. Prevention: Do not remove goggles while working with chemicals. Response: Alert teacher while walking to eyewash station; use eyewash station for at least 15 minutes.

Page 13

1. B

2. A, B, D

3. Sample answer: Moving objects can roll under feet and cause accidents; marbles can roll or fall off tables.

4. Sample answer: Use a box to catch the rolling marbles at the bottom of the ramp; make sure groups are not working too close together.

5. Prevention: Label test tubes before filling. Response: Ask the teacher how to dispose of solutions. Dispose of the solutions, clean test tubes, label test tubes, and start over.

Page 23

1. B

2. C

3. Sample answer: Hold the stirring rod against the mouth of the container you are pouring from. Pour liquid along the stirring rod so it flows down the rod into the second container.

4. Prevention: Heat the test tube from the upper portion downward, moving the tube continuously. Response: Remove the test tube from the flame and carefully place it in a beaker. Ask the teacher for instructions on how to dispose of the test tube once it is cool.

Page 36

1. B

2. D

3. Sample answer: Compare temperature readings from the temperature probe and a regular thermometer. Another possibility is to calibrate the probe by taking measurements of substances at known temperatures, such as ice water and boiling water.

4. Prevention: Tare the balance with the weigh boat before adding the object. Response: Use the balance to find the mass of the weigh boat, then subtract that amount from all mass measurements.

LAB SAFETY HANDBOOK

Answer Key



Documents

Lab Safety Handbook - St. Louis Public Schools