CHEM 1010 Chemistry

Lab 1 – Safety Regulations, Measurements, and Density of Water

Safety Regulations

To ensure that a safe and healthful environment is maintained while taking your

chemistry course, everyone should read the following safety regulations listed below.

1. You should prepare for each laboratory (after this first one) by reading all the instructions

and completing the prelab assignment for the experiment before coming to class.

2. Wear approved eye goggles at all times while working in the laboratory. If you wear

your own frame eyeglasses, the goggles must be worn over them. The National Institute

for Occupational Safety and Health (NIOSH) states that it is considered safe to wear

contact lenses in lab, but only if eye goggles are worn over them.

3. Your apparel should be appropriate for laboratory work. Wear protective closed-toe

shoes (neither sandals nor thongs), a lab coat, and gloves when working in the

laboratory with chemicals and equipment. Tie back long hair, and do not wear long,

dangling jewelry or clothes with loose and baggy sleeves. Cotton clothing is preferred

over nylon, polyester, or wool.

4. Everyone should be alert and proceed with caution at all times in the laboratory. Take

care not to bump another student and remain in your lab station while performing an

experiment. An unattended experiment can produce an accident.

5. Only the laboratory handout is permitted on the laboratory bench top. Other books,

purses, and such items should be placed in an appropriate storage area.

6. No food, beverage, or smoking is permitted in any science laboratory.

7. Never taste chemicals. Treat all chemicals as if they were poisonous unless you know

them to be otherwise. Minimize their contact with your skin and clothing and avoid

breathing vapors and dust.

8. Extreme caution should be exercised when using a burner. Keep your head and clothing

away from the flame and turn off the burner when not in use. Gas burners should be

lighted only with a sparker. Check to see that all gas valves are turned off before leaving

the laboratory.

9. Work areas and apparatus should be kept clean and neat. You should always clean, and

wipe dry, all apparatus, desks, tables, or laboratory work areas at the conclusion of each

laboratory experiment.

10. Hands should be washed thoroughly with soap at the conclusion of each laboratory.

11. You should know the locations and operations of all Safety Control Equipment listed on

the following pages.

12. All accidents should be reported to the instructor immediately, no matter how minor.

13. Broken glassware and porcelain should be cleaned up immediately as disposed of in the

broken glass box near the instructor’s desk.

14. If a chemical should splash on your skin or clothing, wash it off immediately with a

large amount of water and then consult the instructor.

15. If a chemical should splash into your eye, immediately wash the eye with a large

amount of water from the eye and face wash fountain. Continue washing and notify

the instructor.

16. Flammable materials should only be used in small amounts, in closed containers

whenever possible, and never around flames.

17. When diluting concentrated acids, always pour the concentrated acid into water to

dissipate the heat produced and to prevent splattering.

18. Never work alone in the lab. You should only work in the laboratory during your

scheduled laboratory period while under the supervision of your instructor.

Safety Control Equipment

Instruments and tools play an important part in the safety program of your chemistry course.

Throughout this course, references are made to equipment and devices used to prevent

accidents from occurring in the laboratory. Before experimenting in the laboratory, you

should become familiar with the safety equipment listed below, know their locations, and

gain experience in actually using these items. All equipment should be easily accessible to

everyone and should be checked periodically to assure proper operation and cleanliness.

1. Eye and Face Wash Fountains

Fountains prevent or reduce injuries from chemicals splashing in or near the eyes. The

fountain is designed to provide a gentle flow of aerated water to cleanse the eye and

surrounding areas of foreign substances for at least 15 minutes at a time. The eye and face

wash fountain are found to the right of the whiteboard in the front of the lab room.

2. Safety Showers

Showers prevent or reduce injuries from caustic chemicals or acid burns, from contact

with toxic chemical reagents, or from clothing fires. The showerheads must be a non-

clogging, deluge-type capable of covering a contaminated area of skin with a flood of

water that is sufficient to dilute material to a safe level in 15 seconds. The safety shower

is found to the right of the whiteboard in the front of the lab room.

3. Fire Extinguishers

Extinguishers are used to put out fires. The instructor and students should be familiar

with the operating instructions for all fire extinguishers. The fire extinguisher is found to

the left of the whiteboard in the front of the lab room.

4. Fume Hood

Fume hoods prevent the spreading of poisonous gases evolved in an experiment. Each

laboratory station is equipped with a snorkel fume hood, and there are two large fume

hoods found on the two sides of the lab room.

5. First Aid Kits

First Aid Kits are used to give emergency treatment for burns, cuts, and so on. Only the

instructor or the stockroom technicians should administer treatment. The first aid kit is found

in a drawer near the instructor’s desk.

6. Safety Goggles

Goggles protect your eyes from chemical and particle injuries. Students are not allowed to

wear safety glasses with side shields. The most commonly used in school laboratories is a

flexible soft-sided plastic model with a single large plastic lens. The goggles are available

with baffled vents on the sides, so that air can flow through, but liquids will not enter.

Goggles should be worn over prescription glasses and may be worn over contact lenses as

well. Goggles will be provided by the instructor, should be washed frequently, and should be

stored in a protected place, such as your laboratory locker.

7. Gloves

Gloves should be worn when working with chemicals and equipment. When wearing gloves,

you must be careful not to contaminate your work area or other parts of the laboratory with

any chemicals that might have spilled on your gloves. If there is any doubt, gloves should be

removed, and a new pair put on. Glove dispensers are found on both sides of the whiteboard

in the front of the lab room.

8. Lab Coats

A lab coat protects clothing and skin from chemical spills. A lab coat will be provided by the

instructor and should be stored in a protected place, such as your laboratory locker.

9. Tongs

Tongs protect the hands from burns and chemical injuries. Always remember to use them

when handling heated materials, especially in glass or porcelain containers. Crucible tongs

and beaker tongs are found in drawer 030, beneath the back counter of the lab room.

10. Chemical Waste Containers

The chemical waste containers prevent fires, explosions, and pollution. Chemical waste

containers will be found in the large fume hood labeled A on the side of the lab room near the

Lab Support door.

*** At the end of the lab period, students need to turn in : Prelab questions, Postlab questions,

Activity #1 Report, Activity #2 Report for graded.

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2

3

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Pre-Lab Questions:

Name: Group #: __________________

Date/Lab Start Time: ___________________Pre-Lab Score: _________

1. Identify each item on the previous page.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

(j)

(k)

(l)

(m)

(n)

(o)

(p)

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Activities 1 Report:

Name: Group #: ________________

Date/Lab Start Time: _________________________________ Report #1 Score: _________

Measurements:

Introduction:

In this experiment we will become familiar with several instruments. The accuracy of every

measurement that is made depends on the equipment used to make the measurement. We will

take mass measurements on a multiple beam balance and an analytical balance. When

reading a graduated piece of equipment, such as a multiple beam balance, the tolerance, or

uncertainty, of the measurement is taken as one-half the closest divisions. We will use a

multiple beam balance in which the closest divisions represent 0.1 g. Dividing the closest

divisions by 2 gives us the tolerance of this multiple beam balance: 0.05 g. Because the

tolerance is five hundredths of a gram, the mass is recorded to the hundredths of a gram to

match the recorded mass with the instrument’s tolerance. Two different measurements from

such a balance may be written as

6.34 g or 15.90 g

Our analytical milligram balances have a tolerance of one thousandth of a gram.

Measurements made with this instrument should always be recorded to the thousandths

place, inferring that its tolerance is in the thousandth of a gram range. Measurements made

on an analytical milligram balance may be written as

64.203 g or 15.528 g

We will make volume measurements of liquids in graduated cylinders. When reading a

graduated cylinder, always read the bottom of the meniscus, the lens-shaped surface of the

liquid. Observe the meniscus at eye level in order to avoid a reading error. Once again, when

reading a graduated piece of equipment, the tolerance of the measurement is taken as one-

half the closest divisions. We will use our smallest graduated cylinder in which the closest

graduations represent 0.1 mL. Dividing the closest graduations by 2 gives us the tolerance of

this graduated cylinder: 0.05 mL. Because the tolerance is five hundredths of a milliliter, the

volume is recorded to the hundredths of a milliliter to match the recorded volume with the

instrument’s tolerance.

Two different measurements from such a graduated cylinder may be written as

7.00 mL or 3.25 mL

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On our largest graduated cylinder, the closest graduations represent 1 mL, and therefore has a

tolerance of

0.5 mL. Two different measurements from such a graduated cylinder may be written.

31.0 mL or 42.5 mL

Temperature measurements will be made using a thermometer in which the closest divisions

represent 1ºC, and therefore has a tolerance of 0.5ºC. Two different measurements from this

thermometer may be written as

11.0ºC or 78.5ºC

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We will make length measurements using two different metric rulers. On the first ruler below

the closest divisions represent 1 cm, and therefore has a tolerance of 0.5 cm. A measurement

of the length of the copper rod from this ruler may be written.

12.5 cm

On the second ruler below the closest divisions represent 0.1 cm, and therefore has a

tolerance of 0.05 cm. A measurement of the length of the same copper rod from this ruler

may be written as

12.55 cm

Table 1

When doing multiplication or division operations involving measurements, the number of

significant figures in the answer must equal the number of significant figures in the factor

that has the least number of significant figures. When multiplying 2.7 cm by 9.4 cm, because

each factor has 2 significant figures, the answer must be rounded to 2 significant figures. Our

answer must be given as

2.7 cm x 9.4 cm = 25 cm2

When multiplying 2.76 cm by 9.35 cm, because each factor has 3 significant figures, the

answer must be rounded to 3 significant figures. Our answer must be given as

2.76 cm x 9.35 cm =25.8cm2

Begin each experiment by taking the necessary safety precautions. Get in the "good habit" of

always putting on your safety goggles and lab coat. All materials that will not be used in the

lab should be placed out of the laboratory working area. This would include books, lunched,

etc. The best way to become familiar with chemical apparatus is actually to handle the pieces

yourself in the laboratory.

Reading from figures Actual measurements

Copper rod A

Copper rob B

A

B

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Post Lab Questions:

Name: Group #: ________________

Date/Lab Start Time: ___________________________ Post Lab Score: _________

1. State the number of significant figures in each measurement.

(a) 35 s

(c) 1.05 cm

(e) 21.50 mL

(g) 67.0 g

(i) 900 cm3

(b) 10.00 mL

(d) 30.5 cm3

(f) -20.0ºC

(h) 0.018 g

(j) 40ºC

2. Perform each arithmetic operation and round off the answer to the proper number

of significant figures. Box your answer.

(a) 50.4 g (b) 63.05 cm + 50.07 g -11.4 cm

50.213 g

3. Perform each arithmetic operation and round off the answer to the proper number

of significant figures. Box your answer.

(a) (47.905 cm) (0.20 cm) (b) 639.5 mm3

24.5 mm

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4. Give the measurement indicated by each of the following. The reading must be

consistent with the tolerance of the instrument.

cm

cm

cm

cm

Table 1: Please use the materials/tools provided to measure and record data.

Actual Measurements Units ( cm)

Rectangular rod

Magnesium ribbon

Copper wire

Glass tubing

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mL mL ºC ºC

Table 2:

Please pour a desired amount of distilled water to a graduated cylinder, read the measurement, and

record the data in the table below.

After measuring, please dip the thermometer inside the distilled water, measure the temperature and

record the data.

*Be careful with the significant digits and corrected units.

Actual measurements Unit ( mL or oC/

oF)

Graduated cylinder

Thermometer

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5. Perform the indicated operations. Box your answers.

A .

Solve for V

B. PV = nRT Solve for M (molar mass) if n =

C. n =

Solve for m ( mass of an object )

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Activities 2 Report:

Name: Group #: ________________

Date/Lab Start Time: _________________________________ Report #2 Score: _________

Objectives

To determine the density of pure water and the density of a penny.

Background

Density is defined as the mas per unit volume of a substance, and it is a physical property of matter.

A pure substance has unique density values, measuring the density of a substance can help identify

that substance.

The formula of calculating density is:

Density = Mass/Volume

The unit of density are commonly expressed as g/cm3 for solid, g/mL for liquids, and g/L for gases.

In this part, the mass and volume of distilled water will be measured in order to determine the

density of water. Measurements will be performed on three samples of water to improve precision

and accuracy.

Mass will be measured with an electronic balance ( unit in grams (g) ).

Volume will be measure with a graduated cylinder ( unit in milliliters (mL) ).

We must read from the lowest point of the meniscus; the correct reading is 30.0 mL. The first 2

digits are known, the last digit is uncertain. Even though it is zero, it is a significant and must be

recorded.

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Water displacement method:

Unit conversion: 1mL = 1cm3

Formulas:

Area of a rectangle = Length x Width

Volume of a box = Length x Width x Height

Volume of a cylinder = ; h = cylinder height or length, r = radius of the cylinder = ½ diameter

Linear Equation – Slope intercept form: y = mx+b ; m = slope , b is y-intercept.

Slope (m) =

*Once the density is determined in this manner, it will be used to identify the unknown material

analyzed.

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Materials and Equipment:

100 mL graduated cylinder

Metric ruler

50mL beaker

1 Thermometer

1 electronic balance

250mL of distilled water

5-10 pennies per group

Procedure:

1. Measure the mass of your 100 mL graduated cylinder. Make sure it is dry before you weight

it.

2. Add 10mL of distilled water to the graduated cylinder. Precisely measure the volume of

water. Then measure the combined mass using the electronic balance. Record data in Table 1.

3. Add another 10mL of distilled water to the graduated cylinder. Repeat the same process as

step 2. Record data in Table 1

4. Repeat step 3 to obtain a 3rd

set of mass and volume measurements. Record data in Table 1.

5. Use your thermometer to record the temperature of the water in your graduated cylinder.

Record data in Table 1.

Analysis:

1. Subtract the mass of the empty cylinder from each combined mass measurement to obtain

three mass measurements of water.

2. Use three sets of mass and volume measurements to calculate three density values of water.

3. Take the average of three density values.

4. Compare your result with the true density of water at the temperature used.

Density of a penny. Take a few pennies. Use the scale to find the mass of the pennies. Place the

pennies in graduated cylinder with 30ml of water. See how much the volume changes. The change

in volume of the water is the volume of the pennies. Record the data below. Please pour out all the

water and dry out the pennies before returning them to your instructor!

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Experiment Data

Table 1:

1st Water Addition 2

nd Water Addition 3

rd Water Addition

Mass of Empty Cylinder

Mass of Cylinder + Water

Mass of Water only

Volume of Water

Density of Water

Average Density of Water

Temperature of Water

Record the mass of the pennies ______(g). What is the volume of the pennies____ (ml)

Please answer these following questions:

1. Circle the correct response in the following statement:

Density is a physical/chemical property of matter

2. What devices did you use to measure the mass and the volume of water in this lab?

3. What is the true density of water at the room temperature?

Find the percent error between your calculated density of water with the true density of water.

Percent of error =

4. The density of pure copper is 8.96g/cm3. Is the penny made of real copper? Why or Why not?

5. How would you improve the accuracy of your experiments?