One method of classification would be to separate the substances by state. All the substances in this room could be grouped into solids, liquids, or gases.

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Technical Science

Introduction to Chemistry

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States of Matter

● In this section you will…

– Describe the Three States of Matter

– Describe the Factors Affecting Gases

– Relate Temperature, Volume, and Pressure.

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Describe the Three States

of Matter

● One method of classification would be to

separate the substances by state.

● All the substances in this room could be

grouped into solids, liquids, or gases.

● If you were to classify the substances in this

room, how would you do it?

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Describe the Three States

of Matter

● What determines the state of a substance?

● The state of any substance can be changed

by adding or removing heat.

● The substances in this room are either solid,

liquid, or gas.

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Solid

+ Heat

Liquid

+ Heat

Gas

- Heat

Gas Liquid

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The process of changing from solid to liquid is called Melting.

The process of changing from liquid to solid is Freezing

Describe the Three States

of Matter

● There is some important terminology associated with changing states.

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Solid Liquid

Gas

The temperature at which a solid turns into a liquid is called the

Melting Point

Melting

Freezing The process of changing from

liquid to gas is called Vaporization.

The process of changing from gas to liquid is Condensation

Vaporization

Condensation

Boiling Point

The temperature at which a liquid turns into a gas is called the

Boiling Point

The process of changing from solid to gas is called Sublimation.

The process of changing from

gas to solid is Condensation _Sublimation

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Describe the Three States

of Matter

● Match the terminology from the previous slide to define water in the situations described below.

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- Water vapor forms droplets on a cold can of soda.

- 100° Celsius - 212 ° Fahrenheit

- A pile of snow disappears although the temperature is below freezing.

- The ice cubes in your soda disappear

- 0° Celsius - 32 ° Fahrenheit

- The surface of the lake solidifies

- The sun evaporates water from a lake

Melting

Freezing

Condensation

Vaporization

Sublimation

Freezing Point

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Describe the Three States

of Matter

● What happens to the particles in a substance when the state is changed?

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● Remember, to change the state of any substance you add or remove heat.

Solid

+ Heat

Liquid

+ Heat

Gas

- Heat

Gas Liquid

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Describe the Three States

of Matter

● When a solid is heated, the particles gain energy and move faster.

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● They move further away from each other so the substance becomes less dense.

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Describe the Three States

of Matter

● When a liquid is heated, the particles gain more energy and move even faster.

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● They move further away from each other so the substance becomes even less dense.

● The forces that hold one particle to another are

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Describe the Three States

of Matter

● As a substance cools the reverse happens.

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● The gas particles lose heat, slow down, become more dense, and condense into a liquid.

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Describe the Three States

of Matter

● A substance changes state because of the addition or removal of heat.

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● But the substance itself is not changed when its state is changed.

● For example; ice, water, and steam are all

composed of water (H₂O) particles. The only difference is the amount of heat energy.

H

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Describe the Three States

of Matter

Solids

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● In a solid, the particles are “locked” into specific arrangements making them rigid.

● Solids maintain a specific shape and volume

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1 in3

Describe the Three States

of Matter

Solids

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● Since solids maintain a specific shape and volume, the container you put them in won’t matter.

1 in3

1 in3 1 in3

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Describe the Three States

of Matter

Solids

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● We rely heavily on these properties of solids.

● When we build a car or a building or a bridge, we want to make sure that it retains its shape and

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Describe the Three States

of Matter

Liquids

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● In a liquid, there is some attraction between

particles but they are not “locked” into a specific arrangement.

● The particles in a liquid are free to slide past one another making them fluid.

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Describe the Three States

of Matter

Liquids

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● Since liquids are fluid, they will change shape to fit their container.

50 ml

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Describe the Three States

of Matter

Liquids

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● Hydraulic systems rely on the ability of fluids to change shape but retain a constant volume.

● Since a liquid can change shape, it can be pushed through pipes, cylinders, and hoses.

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Describe the Three States

of Matter

Gases

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● In a gas, there is little or no attraction between particles because they are relatively far apart.

● The particles in a gas are also moving rapidly in every direction because they have a lot of energy.

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Describe the Three States

of Matter

Gases

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● Gases are also fluid, they will change shape to fit their container.

50 ml

50 ml 50 ml

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Describe the Three States

of Matter

Gases

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Home

● Solids have constant shape and volume

Liquids have constant volume but variable shape. Gases have variable shape and volume

● This means gases can be expanded or compressed and they can take on the shape of any container

● Because gases are so variable they are affected to a great extent by environmental factors like;

Temperature, Volume, and Pressure.

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Describe the Factors

Affecting Gases

● We will discuss Temperature, Volume, and

Pressure and their relationship to the behavior of gases.

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Describe the Factors

Affecting Gases

Temperature

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● Temperature is a measure of the amount of heat in a substance.

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Describe the Factors

Affecting Gases

Volume

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● Volume is a measure of the space that a gas occupies.

● A given number of gas particles will expand or

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Describe the Factors

Affecting Gases

Pressure

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● Pressure is a multidimensional property composed of the basic units of force and area.

● Pressure is measured in units such as… Pressure = Force

Area

Pressure = Force

Area =

Pounds

Square Inch =

Newtons

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Describe the Factors

Affecting Gases

Pressure

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● In what situations have you heard the term pressure?

Α You have had your blood pressure taken when you

go to the doctor. This is a measure of the force with which your blood pushes on the walls of your vessels.

Α At some point, you have probably measured the air

pressure in a car or bike tire. A pressure of

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Describe the Factors

Affecting Gases

Pressure

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● Your body is currently under pressure from the weight of the atmosphere pushing on you.

● Standard atmospheric pressure is 14.7 lb / in2.

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Describe the Factors

Affecting Gases

Pressure

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● There are a number of different units that may be used to measure atmospheric pressure.

● The different units are the result of using different measuring instruments.

● If you listen to the weather forecast you also know that atmospheric pressure can change. This is

based, in part, on temperature and elevation.

Standard Atmospheric Pressure 14.7 lb

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Describe the Factors

Affecting Gases

Pressure

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● You are able to withstand the atmospheric pressure because your body evolved to handle it.

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Describe the Factors

Affecting Gases

Pressure

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● What would happen to your body if you were sent into space where there is no atmosphere?

Α If there is no atmosphere then there is no external

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Describe the Factors

Affecting Gases

Pressure

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● If you pump up a bike tire to 65 lb/in2, What are the air particles doing that keeps the tire inflated?

Α Gas particles are constantly moving in every

direction. As they collide with the inner walls of the tire they exert a force on the inside of tire. The sum of the forces of all those collisions is

what accounts for the pressure that keeps the tire inflated.

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Home

Relate Temperature,

Volume, and Pressure

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● In other words; if we change one factor, what

will happen to the other?

● In this section, you will explore the

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Relate Temperature,

Volume, and Pressure

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Temperature and Volume

● As you increase the temperature of a gas the particles move further away from each other.

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Relate Temperature,

Volume, and Pressure

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Temperature and Volume

● As the temperature increases and the gas particles move further away from each other, the gas

becomes less dense.

● This is what makes a hot air balloon fly.

● The air in the balloon is warmer and therefore less dense.

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Relate Temperature,

Volume, and Pressure

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Temperature and Pressure

● As the temperature in an enclosed container

increases and the gas particles move faster they hit the walls of the container with more force.

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Relate Temperature,

Volume, and Pressure

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Temperature and Pressure

● As the temperature in a container increases, the gas particles move faster and the pressure increases.

● This is the principle behind a pressure cooker.

● As the heat increases inside the sealed pot, the pressure also increases.

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Relate Temperature,

Volume, and Pressure

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Pressure and Volume

● As the pressure on a gas increases, the space the gas occupies is decreased.

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Relate Temperature,

Volume, and Pressure

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Pressure and Volume

● As the pressure on a gas increases, the space the gas occupies decreases.

● If you bought a tank of propane gas to use with your gas grill, the gas would be under pressure.

● Putting a gas under pressure can decrease it’s volume. This means that you can store more propane particles in the same amount of space.

Propane

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Relate Temperature,

Volume, and Pressure

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Review

● The factors Temperature and Volume are directly related because as one increases the other increases and if one decreases the other decreases.

● Temperature and Pressure are also directly related

because they go up and down together.

● Pressure and Volume are indirectly related because as one increases the other decreases.

Temperature ____ Volume ____

Temperature ____ Pressure ____

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Relate Temperature,

Volume, and Pressure

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● The relationships you just studied are often called the Gas Laws because they govern the behavior of gases.

● Complete the statements below to summarize the Gas Laws

If Temperature ___________ then Volume ____________

If Temperature ___________ then Pressure ____________

If Pressure ___________ then Volume ____________

decreases decreases

decreases increases

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Use the Gas Laws

to Solve Problems

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● The relationships described by the Gas Laws can be used to calculate temperatures, volumes and

pressures.

Home

● The following is an example of the type of problem you will solve.

● 4 liters of air is heated from 0°C until its volume reaches 4.5 liters. What is the final temperature?

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Use the Gas Laws

to Solve Problems

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Ex. 4 liters of air is heated from 0°C until its

volume reaches 4.5 liters. What’s the final temp?



You must remember the relationships between Temperature, Volume, &

Pressure Temperature ____ Volume ____

Temperature ____ Pressure ____

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Use the Gas Laws

to Solve Problems

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Ex. 4 liters of air is heated from 0°C until its volume reaches 4.5 liters. What’s the final temp?

● You will need to determine appropriate units of measure for each factor. Temperature,

Pressure, and Volume. Pressure

Any pressure unit (torr, lb/in2, etc) is suitable as long as you are consistent

from beginning to end.

*Temperature*

When solving gas law problems all temperatures MUST be in Kelvin

K = C + 273

273 K liters

liters.

Volume

Any volume unit (liters, ft3, etc) is suitable as long as you are consistent

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Use the Gas Laws

to Solve Problems

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Ex. 4 liters of air is heated from 273 K until its

volume reaches 4.5 liters. What’s the final temp?



You will need to distinguish between the initial and the final conditions stated in the

problem Initial (1) Final (2)

V

1 = 4 liters

T₁ = 273 K

V

2 = 4.5 liters

T

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Use the Gas Laws

to Solve Problems

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

Sometimes problems will make reference to “standard”

temperature and pressure. You need to know the values

associated with these “standards”

Standard Temperature

Standard Temperature = 273 K

Remember, temperature is always in Kelvin.

Standard Pressure

Standard Pressure = 1 atmosphere = 760 mm Hg = 760 torr = 14.7 lb/in2 Remember, pressure can be in any units as long as you stay consistent

from the initial to the final conditions.

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Use the Gas Laws

to Solve Problems

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● 4 liters of air is heated from 0°C until its volume reaches 4.5 liters. What is the final temperature?

Now, let’s actually solve some problems.

Step 1: Identify and record the initial and final

conditions. Initial Final

V₁= 4 liters T

1 = 0° C

V₂= 4.5 liters T₂=

Temp must be in Kelvin. K = C + 273

0°C = 273 K 273 K

273 K _x 1

4.5 l

4 l =

273 x 4.5 ÷ 4 = 307 307 K 307 K

There is an initial temperature but no final temperature.

So start with the 273 K

In this problem the volume is going UP from 4 liters to 4.5 liters

Ask yourself, “What will happen to the temp if the volume goes up?” The temperature will go up as well. The final temperature must get bigger. So, we will put the larger volume on top

and the smaller on the bottom Step 2: Check for

appropriate units of measure.

Step 3: Start your calculation with the initial condition that has

no pair. Set the problem up as a conversion factor.

Step 4: Determine the correct position for the remaining pairs of factors. Which one goes on top and

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Use the Gas Laws

to Solve Problems

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● A car tire is inflated to 36 lb/in2 on a 90°F day. If the temp drops to 0 °F, what would the pressure be?

T₁= 90° F P

1 = 36 lb/in 2

T₂= 0° F P₂=

Temp must be in Kelvin. C = 5/9(F – 32) K = C + 273 90° F = 305 K 0° F = 255 K 305 K

36 lb/in2 _x 1

255 K 305 K =

36 x 255 ÷ 305 = 30

30 lb/in2

There is an initial pressure but no final pressure. So start with the 36 lb/in2 In this problem, the temperature

is going DOWN from 305 K to 255 K

Ask yourself, “What happens to the pressure if the temp goes down?” The pressure will go down as well. The final pressure must get smaller. So, we will put the smaller temp on top

and the larger on the bottom. Step 2: Check for

which one goes on the bottom. Step 5: Perform the calculation.

255 K

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Use the Gas Laws

to Solve Problems

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● A bike tire has a volume of 46 in3 and is inflated to 65 lb/in2 . If the volume increased to 60 in3, what would happen to the pressure?

V₁= 46 in3 P

1 = 65 lb/in 2

V₂= 60 in3 P₂=

in3 are units of volume and they are consistent from initial to final.

lb/in2 are units of pressure 65 lb/in2 _x

1

46 in3 60 in3 =

65 x 46 ÷ 60 = 50

50 lb/in2

There is an initial pressure but no final pressure. So start with the 65 lb/in2 In this problem, the volume

is going UP from 46 in3 to 60in3

Ask yourself, “What happens to the pressure if the volume goes up?”

The pressure will go down.

The final pressure must get smaller. So, we will put the smaller volume on

top and the larger on the bottom. Step 2: Check for

which one goes on the bottom. Step 5: Perform the calculation.

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P₁ x 2

Standard Temp = 273 K Standard Pressure = 760 torr

Use the Gas Laws

to Solve Problems

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● Air at standard temp and pressure occupies a

volume of 8 liters. What will the volume be if the pressure is doubled and the temp goes to 25 °C ?

T₁= 273 K P₁= 760 torr

T₂= 25° C P₂=

T₂ must be in Kelvin 25° C = 298 K The other units are appropriate and

consistent from beginning to end.

8 liters _x 1

298 K

273 K =

8 x 298 ÷ 273 x 760 ÷ 1520 = 4.4

4.4 liters

There is an initial volume but no final volume. So start with the 8 liters.

In this problem, the temperature is going UP

from 273 K to 298 K

Ask yourself, “What happens to the volume if the temp goes up?”

The volume will go up.

The final volume must get bigger. So, we will put the bigger temp on top and the smaller on the bottom.

Step 2: Check for appropriate units of

measure.

which one goes on the bottom. 4.4 liters

V

1 = 8 liters

1520 torr

V₂=

298 K

In this problem, there are 2 changes. The pressure is going up as well

from 760 torr to 1520 torr

Ask yourself, “What happens to the volume if the pressure goes up?”

The volume goes down.

The final volume must get smaller. So, we will put the smaller pressure on top and the larger on the bottom.

x 760 torr 1520 torr

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Use the Gas Laws

to Solve Problems

The following slides will present one or two practice problems of each type. Try them on

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11 of 17

Use the Gas Laws

to Solve Problems

● Air at 260 K has a pressure of 750 mm of Hg. If the temperature increases to 292 K, what is the new pressure?

750 mm Hg x 292 K

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12 of 17

Use the Gas Laws

to Solve Problems

● 10 liters of air is at 770 torr. What is the volume if the pressure drops to 730 torr?

10 liters _x 770 torr

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13 of 17

Use the Gas Laws

to Solve Problems

● 2 cubic feet of gas is at 30° C. What will its volume be if the temperature drops to 15° C?

2 ft3 _x 288 K

303 K = 1.9 ft

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14 of 17

Use the Gas Laws

to Solve Problems

● Propane in a 2 ft3 tank is under 150 lb/in2 of

pressure. If the tank became dented so the volume dropped to 1.8 ft3, what would happen to the

pressure?

150 lb/in2 _x 2 ft3

1.8 ft3 = 167 lb/in

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15 of 17

Use the Gas Laws

to Solve Problems

● A quantity of air is at standard temperature and pressure. If the pressure is decreased to 0.75 atmospheres, what is the new temperature?

273 K _x 0.75 atm

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16 of 17

Use the Gas Laws

to Solve Problems

● 5 liters of gas at 41° F increases to volume of 5.5 liters. What is the new temperature in ° F?

41° F = 278 K _x 5.5 liters 5 liters

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Use the Gas Laws

to Solve Problems

● Air at standard temperature and pressure occupies a volume of 15 liters. What will the volume be if the temperature decreases to -10° C and the pressure drops to 740 torr.

15 liters x 263 K

273 K x = 14.8 liters 760 torr

740 torr

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