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Nature of MatterCNS 8Unit 2
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Matter- forms of , Kinetic Theory (particle theory)Changing states of matter, heating curveHeat of fusion, heat of vaprorizationMelting, freezing, boiling pointsChemical and physical propertiesChemical and physical changesLaw of Conservation of MassMixture, compound, elementsCrystallline and amorphous solidsDensity, buoyancy, Archimedes principle
UNIT TWO PREVIEW........
What are the States of Matter?
SolidLiquidGasPlasma
SolidsEvery solid has a definite shape & a definite volume.
Tiny particles in constant motion make up
all matter.
This idea is called the kinetic theory of matter.
Particles in a solid are held close together by forces between them. They vibrate, but lack the energy to move out of position.
This is why a solid holds its shape.
Crystalline Solids
In most solids, the particles are arranged in repeating, geometric shapes. We call these shapes crystals.
SALT
SNOWFLAKE CRYSTALS
Noncrystalline Solids
Some materials look like solids, but are not made of crystals. We call these amorphous solids. Some scientists think we should classify these things as "thick liquids"!What items are we talking about?
Glass
Plastics Gels
Liquids
A liquid flows and takes the shape of its container.
Kinetic theory explains the properties of solids and of liquids too!
The particles are close together (like in a solid) but have enough kinetic energy to move over and around each other.
This movement of particles lets a liquid flow and take the shape of the container.
Liquids have a definite size and volume but an irregular shape.
GasesGases are "springy", they expand or contract to fill the available space. They can be squeezed into a certain space.
Gases do not have a definite shape or volume.
Plasma
A gas like mixture of positively and negatively charged particles.
The most common form of matter in our universe.
Found in stars and nebula.
Also in fluorescent light.
KINETIC THEORY OF MATTER
All matter is made up of tiny particles that are in constant motion. When energy is absorbed the particles will move faster, and when energy is released the particles will move slower.
Substances can be changed from one state to another.
Particles in matter are held together by attractive forces. As these particles gain energy, the particles move faster and farther apart.
Solids melt...... liquids change to a gas....
Changing States of Matter
KINETIC THEORY OF MATTER
All matter is made up of tiny particles that are in constant motion. When energy is absorbed the particles will move faster, and when energy is released the particles will move slower.
Changes in States of Matter
Vaporization-add heat to a liquid until it reaches a temperature at which it changes to bubbles of gas below the surface.
Evaporation- a liquid changes to a gas gradually at temperatures below the boiling point.
ex: air drying after swimming ex: air drying wet cement
Condensation- when a gas changes to a liquid.
ex: car windows with dew ex: mirror after a shower
The kinetic theory of matter explains changes of state. The amount of energy needed to change a material from the solid state to a liquid state is the heat of fusion. Water heat of fusion is 334kJ/kg
Amount of energy needed to change a material from a liquid to a gas is the heat of vaporization.Water heat of vaporization is 2260kJ/kg
Ice is at -20oC. As the ice is heated, the water molecules gain kinetic energy and move faster. Temp of ice rises to 0 degrees then stops rising. As more heat is added, the motion of the molecules does not increase. Instead the molecules overcome the forces that hold them together in the form of a solid. The molecules move farther apart and the ice melts.
Heat = mass x heat of vaporization
The temperature at which the ice melts is the melting point. Both solid and liquid exist at this temperature.
The amount of heat energy that change a solid to a liquid is call the heat of fusion.
Each substance has a characteristic heat of fusion.
Heat = mass x heat of vaporization
ENERGY
Just as there are many forms of energy, there are different ways to measure these forms. In science, work and energy are commonly measured in joules.
One joule is the amount of energy it takes to lift an object that weighs one Newton a one meter distance. A Newton is the metric unit for weight and is comparable to the weight of a stick of butter. (1 Newton = 0.445 lbs.)
In our everyday lives, other energy measurements are more familiar to us than joules. Some of these measurements include calories, therms, and kilowatt-hours.
It might seem confusing to have so many different measurements for energy. The good news is that one unit can be converted to another.
Energy
Conversions
British
Thermal Unit
Foot-pounds
Joules calories
Kilo-calories
Kilowatt-hours
1 British
Thermal Unit
1 777.9 1055 252.0 0.252 2.93x10-4
1 Foot-pound
0.001285
1 1.356 0.3238 3.238x10-4
3.766x10-7
1 joule 9.481x10-4
0.7376 1 0.2388 2.388x10-4
2.778x10-7
1 calorie
0.003969
3.088 4.187 1 0.001 1.163x10-6
1 kilocalorie
3.969 3088 4187 1000 1 0.001163
1 kilowatt hour
3413 2.655x106
3.6x106
8.598x105
859.8 1
Kinetic Theory of Matter
Safety CheckTie hair back, loose sleeves rolled up.
Understand the procedure. (READ IT AGAIN!)
Check out the equipment. Practice handling new equipment before you begin the experimental work.
Thermometers in the ice water before you start heating. NEVER PUT A THERMOMETER INTO HOT WATER ON AN ALCOHOL BURNER.
Hot water into pail. BE CAREFUL!
GOGGLES ON YOUR FACE, OVER YOUR EYES!
The tare of a container is its weight when it's empty.
To rip a piece of paper into pieces
Tare Tear
1. Balance the triple beam balance.2. Weigh the paper. Record its mass. 3. Take the mass of the paper and ADD IT to the amount of substance that you need.4. Set the balance to the new amount.5. Carefully put the substance onto the paper on the plate of the scale until it balances.
EX: paper = 1g plus 10 g of salt = 11 g total to set on balance.
How to tare......
Safety Check
Tie hair back, loose sleeves rolled up.
Understand the procedure. (READ IT AGAIN!)
Check out the equipment. Practice handling new equipment before you begin the experimental work.
Be careful with lighters. Use the thumb slide, then finger trigger.
Hot water into pail. BE CAREFUL!
GOGGLES ON YOUR FACE, OVER YOUR EYES!
WARNING!
You must be very careful on taking the temperature readings in your experiment.
You must be precise and exact!
Read your thermometers carefully. Pay attention to what you are doing. Both you and your partner
should read and verify each temperature reading.
The marathon (now 26 miles) is still the king of running events, and severely tests the physical endurance of runners. Although it is not known how Phidippides died, it is possible that he could have died of heatstroke, a condition that occurs when body temperatures soar above 105 °F. It is unlikely that Phidippides had much water to drink along his run, probably became quite dehydrated, and no longer was able to sweat. Sweating is essential for temperature regulation, and without it, body temperatures can rise dangerously. When sweat evaporates, it undergoes a change of state from a liquid to a gas. Remember that while something is undergoing a change of state, its temperature remains constant.
Background information:
In 490 BC the Greeks battled the Persians at Marathon, Greece. According to legend, a Greek soldier named Phidippides ran 22.5miles from Marathon to Athens to announce a Greek victory, but died shortly after his announcement. When the modern Olympic Games began in 1896, the marathon was introduced as the main long-distance event to commemorate Phidippides’ run.
Lab: Melting and Boiling Point of Water
Problem: What is the melting point and boiling point of water? When people sweat, how does it help them keep their body temperature constant? How will the addition of salt affect the boiling point of water?
Hypothesis_______________________________________________
Procedure and Materials List:
Materials: 250 ml beaker Alcohol burner and stand Thermometer Ice cubes Water Salt Balance Graduated cylinder
Procedure: Part A. Find the melting point and boiling point of water
1) Put about 50 ml of water and about 2 ice cubes in a 250 ml beaker
2) Wait 1 minute. Then place the thermometer into the beaker and record the temperature (°C). This is the melting point
3) Light your alcohol burner and carefully place it under the stand. Carefully put the beaker on the stand and record the temperature once every 45 seconds.
4) Record the temperature when the water starts to boil. This is the boiling point.
5) After the water has started boiling, record the temperature 3 more times
6) Using beaker tongs, carefully pour the water into the 5 gallon pail.
Part B. Find the boiling point of water with salt added
1) Use a graduated cylinder and put 50 ml of water in a beaker
2) Use a balance to measure 20 grams of salt
3) Add the 20 grams of salt to the water and stir to dissolve 4) Carefully put the beaker on the burner stand, and record the temperature when the water starts to boil.
5) Using the beaker tongs, carefully pour the water into the 5 gallon pail.
6) Repeat steps 1-5 using 40 grams of salt.
0451:302:153:003:454:305:156:006:457:308:159:009:4510:3011:1512:0012:4513:3014:15
Boiling point of water + 15 g salt
Boiling point of water + 40 g salt
Boiling point of water + 20 g salt
Boiling point of water + 40 g salt
A small piece of ice which lived in a test tube fell in love with an alcohol burner.
"Alcohol burner! My flame! I melt whenever I see you" said the ice.
The alcohol burner replied :"It's just a phase you're going through".
Comparing Time and Temperature in Heating Water
1009080706050403020100
Tem
pera
ture
in C
els
ius
Deg
rees
0 45 1:30 2:15 3:00 3:45 4:40 5:15 6:00 7:30 8:15 9:00
Time in Minutes
1) Does the temperature rise when the ice is melting?
No the temperature does not rise when the ice is melting. This is the melting point, and the temperature remains constant.
2) Does the temperature rise after the ice has melted?
Yes, the temperature will rise when the ice has melted and you have all liquid in your beaker.
3) When water is boiling (changing from a liquid to a gas), does its temperature change? Explain how this relates to sweat keeping the body temperature constant. No the temperature will not rise while changing from a liquid to a gas. This is why we sweat, and the sweat cools our bodies so our temperatures do not rise. If we do not sweat, the body temperature will rise to possible dangerous levels.
4) Why would the addition of salt change the boiling point of water?
Usually when you're adding salt to water it's to boil the water to cook rice or pasta. Adding salt to water adds flavor to the water, which is absorbed by the food.
Another reason salt is added to water is because it increases the boiling point of the water, meaning your water will have a higher temperature when you add the pasta, so it will cook better.
That's how it works in theory.
In reality, you would need to add 230 grams of table salt to a liter of water just to raise the boiling point by 2° C. That is 58 grams per half degree Celsius for each liter or kilogram of water. That is much more salt than anyone would care to have in their food.
There are several reasons why the boiling point changes when salt is added to water.
First you have to understand the heat capacity (how much heat is needed to heat a substance) of water and salt. Water has a high heat capacity which means that it needs a lot of heat to warm the liquid up. However, when salt is added to water the heat capacity is lower, therefore less heat is needed to warm the liquid up.
4) Why would the addition of salt change the boiling point of water?
Secondly, you have to observe the amount of salt added to water. However, whatever the percentage of salt to water is, yes the boiling point does change slightly when salt is added.
In fact the boiling point of water will increase with any impurity in the water. With Salty water the boiling point increases and freezing point decreases (but there is no definite boiling point for salt water because it depends on the ratio of salt to water).
Thirdly, when salt is added to H2O, the NaCl (salt- Sodium Chloride) interferes with the H and the O. This stops the liquid from behaving the way it usually does. Like when you freeze salt water...
Graph: Time vs. Temperature for Part A
Heating curve
TIME IN SECONDS
0O
100o
ENERGY
Just as there are many forms of energy, there are different ways to measure these forms. In science, work and energy are commonly measured in joules.
One joule is the amount of energy it takes to lift an object that weighs one Newton a one meter distance. A Newton is the metric unit for weight and is comparable to the weight of a stick of butter. (1 Newton = 0.445 lbs.)
In our everyday lives, other energy measurements are more familiar to us than joules. Some of these measurements include calories, therms, and kilowatt-hours.
It might seem confusing to have so many different measurements for energy. The good news is that one unit can be converted to another.
Energy
Conversions
British
Thermal Unit
Foot-pounds
Joules calories
Kilo-calories
Kilowatt-hours
1 British
Thermal Unit
1 777.9 1055 252.0 0.252 2.93x10-4
1 Foot-pound
0.001285
1 1.356 0.3238 3.238x10-4
3.766x10-7
1 joule 9.481x10-4
0.7376 1 0.2388 2.388x10-4
2.778x10-7
1 calorie
0.003969
3.088 4.187 1 0.001 1.163x10-6
1 kilocalorie
3.969 3088 4187 1000 1 0.001163
1 kilowatt hour
3413 2.655x106
3.6x106
8.598x105
859.8 1
Heat and State ChangesThe kinetic theory of matter explains changes of state. The amount of energy needed to change a material from the solid state to the liquid state is the heat of fusion. For water, the heat of fusion is 334kJ/kg. The amount of energy needed to change a material from a liquid to a gas is the heat of vaporization. For water, this value is 2260 kJ/kg. Study the example below and watch how temperature, energy supplied and the motion of particles are related.
A
B
C
D
A graph that shows how the temperature of a substance changes as it is heated through its state changes is called a heating curve. The heating curve below shows what happens to 18 grams of water when 100 joules of heat energy are added per minute.
HEATING CURVE FOR WATER
100 o
0o A
B
C
D
E
solid
heat of f
usion
liquid
liquid to gasheat of vaporization
gas
Heating curve
solid to liquid
A graph that shows how the temperature of a substance changes as it is heated through its state changes is called a heating curve. The heating curve below shows what happens to 18 grams of water when 100 joules of heat energy are added per minute.
HEATING CURVE FOR WATER
1.What is the theory of kinetic matter?
2. Draw the particles and state the energy level of those particles for each of the following:
solid liquidgas
KINETIC THEORY OF MATTER
All matter is made up of tiny particles that are in constant motion. When energy is absorbed the particles will move faster, and when energy is released the particles will move slower.
Gas
Liquid
Solid
Graph: Time vs. Temperature for Part A
Heating curve
TIME IN SECONDS
0O
100o
A
B
C
D
A change of energy is required for a change of state to occur.
However, while the matter is actually changing from one state to another, the temperature remains constant.
Only after the change has occurred will the temperature begin to increase again.
KINETIC TERMS
As particles are heated they begin to move faster and further apart (the substance EXPANDS). As particles are cooled they begin to move slower and come closer together (it CONTRACTS).
Thermal Expansion
The Heat and Motion Connection
Almost all matter expands as it gets hotter and contracts as it cools. This characteristic of matter is called thermal expansion.
How does kinetic theory of matter explain thermal expansion?
As a solid is heated the particles move faster and faster and vibrate against each other with more force. As a result, the particles spread out from each other.
EX: Crowd of peopleEX: Thermometer
The movement of particles from an area of high concentration to an area of lower concentration. Diffusion increases with higher temperatures.
Diffusion
Air fresheners
work because of diffusion.
As a liquid evaporates off a surface because of heat energy (from your body) it cools the surface .
Evaporative Cooling
Athletes (and you) sweat to cool body’s core temperature.
When you sweat, the moisture comes onto your skin, then evaporates off, and cools you in the process!
Evaporative cooling
Thermal expansion
Evaporative cooling
Diffusion
KINETIC THEORY OF MATTER
All matter is made up of tiny particles that are in constant motion.
When energy is absorbed the particles will move faster, and when energy is released the particles will move slower.
A change of energy is required for a change of state to occur.
However, while the matter is actually changing from one state to another, the temperature remains constant.
Only after the change has occurred will the temperature begin to increase again.
KINETIC THEORY OF MATTER
All matter is made up of tiny particles that are in constant motion. When energy is absorbed the particles will move faster, and when energy is released the particles will move slower.
