Chapter 3 Solids, Liquids, and Gases Table of Contents Chapter Preview 3.1 States of Matter 3.2...

Chapter 3 Solids, Liquids, and Gases

Table of ContentsChapter Preview

3.1 States of Matter

3.2 Changes of State

3.3 The Behavior of Gases


Chapter Preview Questions

1. The space that matter fills is called

a. pressure.

b. area.

c. volume.

d. mass.



2. Which of the following describes a solid?

a. definite volume but no definite shape

b. definite shape and definite volume

c. neither definite shape nor definite volume

d. definite shape but no definite volume



3. Which of the following describes a liquid?







4. Which of the following describes a gas?






Section 1:States of Matter

California Content Standard 8.3.e: Students know that in solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently.


Solids

The particles in a solid are closely locked in position and can only vibrate.


Solids

Solids that are made up of crystals are called crystalline solids.

In amorphous solids, the particles are not arranged in a regular pattern.


Liquids

Compared to particles in a solid, the particles in a liquid are more loosely connected and can collide with and move past one another.


Gases

In gases, the atoms and molecules are free to move independently, colliding frequently.


Section 2:Changes of State

California Content Standard 8.3.d: Students know the states of matter (solid, liquid, gas) depend on molecular motion.

California Content Standard 8.5.d: Students know physical processes include freezing and boiling, in which a material changes form with no chemical reaction.


Changes Between Solid and Liquid• The change in state from a solid to a liquid is called melting. • When a substance melts, the particles in the solid vibrate so

fast that they break free from their fixed positions.• A change from solid to liquid involves an increase in thermal

energy.


Changes Between Solid and Liquid• The change from a liquid to a solid is called freezing.• When a substance freezes, the particles in the liquid

move so slowly that they begin to take on fixed positions.

• The change from liquid to solid involves a decrease in thermal energy.


Changes Between Liquid and Gas• The change from a liquid to

a gas is called vaporization.

• Vaporization that takes place only on the surface of a liquid is called evaporation.


Changes Between Liquid and Gas• Boiling occurs when a liquid

changes to a gas below its surface as well as at the surface.

• The temperature at which a liquid boils is called its boiling point.

• The boiling point of a substance depends on the pressure of the air above it.

• The lower the pressure, the less energy needed for the particles of the liquid to escape into the air.

• Boiling point is a characteristic property of a substance.


Changes Between Liquid and Gas

Condensation •The change in state from a gas to a liquid.•During condensation, the particles in a gas lose enough thermal energy to form a liquid.•Condensation is the reverse of vaporization.•Clouds in the atmosphere form due to condensation.


Changes Between Liquid and Gas

Sublimation •During sublimation, particles of a solid do not pass through the liquid state as they form a gas.•Dry ice, or solid carbon dioxide, is an example of compound that does not turn to liquid at normal atmospheric pressures.


Temperature and Changes of State

A beaker of ice at –10ºC was slowly heated to 110ºC. The graph shows how the temperature of the water changed over time.



Temperature (ºC) on the y-axis, time (minutes) on the x-axis

Reading Graphs:

What two variables are plotted on the graph?



The temperature is rising from 0ºC to 100ºC.

Reading Graphs:

What is happening to the temperature of the water during segment C of the graph?



Segment B: melting point of ice; segment D: boiling point of water

Interpreting Data:

What does the temperature value for segment B represent? For segment D?



Change from solid to liquid; change from liquid to gas

Drawing Conclusions:

What change of state is occurring during segment B of the graph? During segment D?


Section 3:The Behavior of Gases

California Content Standard 8.3.d: Students know the states of matter (solid, liquid, gas) depend on molecular motion.

California Content Standard 8.9.e: Construct appropriate graphs from data and develop quantitative statements about the relationships between variables.


Measuring GasesWhen working with a gas, it is helpful to know its volume, temperature, and pressure.

Volume

Temperature

Because gas particles move and fill the space available, the volume of a gas is the same as the volume of its container.

Temperature is a measure of the average energy of motion of the particles of matter. The faster the particles are moving, the greater their energy and the higher the temperature.


Measuring Gases

When working with a gas, it is helpful to know its volume, temperature, and pressure.

Pressure

Pressure of a gas is the force of its outward push divided by the area of the walls of the container.

Pressure is often measured in units of pascals (Pa) or kilopascals (kPa). It can also be measured in atmospheres (atm) or millimeters of Mercury (mm Hg).


A Change in Pressure

A punctured basketball deflates as gas particles begin to escape.


Temperature and Volume – Charles’s LawWhen the temperature of a gas increases at constant pressure, its volume increases.

The variables are directly proportional to each other, forming a straight line that passes through the origin.


Temperature and Volume – Charles’s Law

When the temperature of a gas is decreased at constant pressure, the volume decreases.


Gas Law Problems – Charles’ LawTemperature Conversion

Equation

Kelvin (K) = °C + 273

Example: 0 °C = 273 K

20 °C = 293 K

V1/T1 = V2/T2

V1 = Volume 1

T1 = Temperature 1

V2 = Volume 2

T2 = Temperature 2


Gas Law Problems – Charles’ LawExample 1:

Calculate the decrease in temperature when 2.00 Liters of gas at a temperature of 20 °C is compressed to 1.00 Liters.

V1/T1 = V2/T2 20 °C = 293 Kelvin

2 L = 1L

293 K x

2x = 293

x = 146.5 Kelvin


Gas Law Problems – Charles’ Law

Example 2:

Calculate the increase in volume when 600 mL of air at a temperature of 20 °C is heated to 60 °C.

V1/T1 = V2/T2 20 °C = 293 Kelvin

60 °C = 333 Kelvin

600 mL = x

293 K 333 K

293x = (600)(333)

293x = 199,800

x = 682 mL



Example 3: Check for Understanding

A gas occupies 900 mL at a temperature of 27 °C. What is the volume at 132 °C?

V1/T1 = V2/T2 27 °C = 300 Kelvin

132 °C = 405 Kelvin

900 mL = x

300 K 405 K

300x = (900)(405)

300x = 364,500

x = 1,215 mL




What change in volume results if 60 mL of gas is cooled from 33 °C to 5 °C?

V1/T1 = V2/T2 33 °C = 306 Kelvin

5 °C = 278 Kelvin

60 mL = x

306 K 278 K

306x = (60)(278)

306x = 16,680

x = 54.5 mL


Pressure and Volume – Boyle’s Law

When the pressure of a gas at constant temperature is increased, the volume of the gas decreases.


Pressure and Volume – Boyle’s Law

When the pressure is decreased, the volume increases.

Gas pressure is inversely proportional to volume at constant temperature. The product of the two variables is a constant.


Gas Law Problems – Boyle’s LawPressure Conversion

Equation

1 atm = 760 mm Hg = 101,325 Pa

Example: 2 atm = 1,520 mm Hg

2 atm = 202,650 Pa

(P1)(V1) = (P2)(V2)

P1 = Pressure 1

V1 = Volume 1

P2 = Pressure 2

V2 = Volume 2


Gas Law Problems – Boyle’s Law

Example 1:

A gas occupies 12.3 liters at a pressure of 40 mm Hg. What is the volume when the pressure is increased to 60 mm Hg?

(P1)(V1) = (P2)(V2)

(12.3)(40) = (60)(x)

492 = 60x

x = 8.2 liters



Example 2:

If a gas occupies 3.60 liters at a pressure of 1 atm, what will its volume be at a pressure of 2.50 atm?

(P1)(V1) = (P2)(V2)

(1)(3.60) = (2.50)(x)

3.60 = 2.50x

x = 1.44 liters




If a gas occupies 1.56 liters at a pressure of 1 atm, what will its volume be at a pressure of 3 atm?

(P1)(V1) = (P2)(V2)

(1)(1.56) = (3)(x)

1.56 = 3x

x = .52 liters




If a gas occupies 600 mL at a pressure of 8 atm, what will its volume be at a pressure of 2 atm?

(P1)(V1) = (P2)(V2)

(8)(600) = (2)(x)

4,800 = 2x

x = 2,400 mL


Pressure and Temperature

When a gas is heated, the particles move faster and collide more often with each other and with the walls of their container. The pressure of the gas increases.


Graphing Gas Behavior

In an experiment, the temperature of a gas at a constant volume was varied. Gas pressure (in kilopascals) was measured after each 5-kelvin change in temperature. The data from the experiment are shown in the table.


Graphing Gas BehaviorGraphing

Use the data to make a line graph. Plot temperature on the horizontal axis with a scale from 270 K to 300 K. Plot pressure on the vertical axis with a scale from 0 kPa to 25 kPa. (1 kPa = 1,000 Pa)



Changing the temperature of a gas at constant volume changes its pressure in a similar way.

Interpreting Data

What was the manipulated variable in this experiment?



Pressure increases with temperature.

Interpreting Data

What kind of trend do the data show?



Gas pressure increases.

Drawing Conclusions

What happens to the pressure of a gas when temperature is increased at constant volume?

Chapter 3 Solids, Liquids, and Gases Table of Contents Chapter Preview 3.1 States of Matter 3.2...

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