Currituck County Schools€¦  · Web viewUnit 5 Gases: Notes Day 1. States of Matter: Describe the molecular motion of solids, liquids, and gases. Draw a picture for each. Solid.

Name: ______________Period: ____ Date: ______

Unit 5 Gases: Notes Day 1

States of Matter: Describe the molecular motion of solids, liquids, and gases. Draw a picture for each.

Solid Liquid Gas

Characteristics of Gases

1. The distance between gas particles is much ____________ the distance between particles of a liquid or solid.

2. Applying ____________ to a gas compresses or pushes the particles closer together.

3. Unlike solids and liquids, gases ______________ fill their containers.

4. Gases have high _____________________ because their particles move more than particles in a solid or liquid.

5. Gases do have _______________.

How do we measure gas properties? Add your definitions below.

kinetic energy: the energy of an object that is due to the object’s motion.

__________________________________________________________________

temperature: measures the average kinetic energy of the particles in an object.

___________________________________________________________________

volume: a measure of the size of an object in three dimensional space.

___________________________________________________________________

pressure: the amount of force exerted per unit area on a surface.

___________________________________________________________________

Today’s Focus: Temperature

Kelvin Celsius

Abbreviation: Abbreviation:

Zero degrees Kelvin is called ________________. Absolute zero is the temperature at which all molecular motion stops.

Absolute zero is -273° C .

273K is the _______________ point of water 0° C is the _________________ point of water

373K is the _________________ point of water 100° C is the ______________ point of water

There are no ______________ Kelvin temperatures. Most of the world uses the Celsius scale on an everyday basis. In the US we use ___________.

Celsius and Kelvin Conversions

The formula: K = oC + 273

Example 1: convert 33oC to Kelvin: Example 2: convert 202K to Celsius:

Illustrate your vocabulary here:

Name: ______________Period: ____ Date: ______

Practice:

Name: ______________Period: ____ Date: ______

1. 10oC =_______K

2. 25oC = _______K

3. -100oC=_______K

4. 400 K=_______oC

5. 300K =_______oC

6. 350K = ______oC

7. 1000K = ______oC

8. 47K = ______oC

9. 42oC = _______K

10. 850oC = ____

Check Your Understanding: Choose the best answer. When you are done, check with your neighbor. Then, ask to see the answer key.1. What is the equivalent of 423 kelvin in degrees Celsius? (a) -223 °C (c) 150 °C (b) -23 °C (d) 696 °C

2. Sucrose decomposes at approximately 160 degrees C to 186 degrees C and turns into caramel. What is this temperature range in Kelvin?

(a) -113 K to -87 K (c) 320 K to 367 K(b) 71 K to 86 K (d) 433 K to 459 K

3. Which of the following is equivalent to 42 oC?

(a) -231 K (c) 273 K(b) 108 K (d) 315 K

4. The temperature at which all molecular motion stops (a) -460 °C (c) 0 K(b) -273 K (d) 0 °C

5. As the temperature of a sample of water decreases, the average kinetic energy of its molecules will

(a) decrease (c) remain the same(b) increase

6. At what temperature does an aqueous solution of silver nitrate have the highest average kinetic energy?

(a) 100 °C (b) 30 K(c) 1000 °C (d) 1000 K

7. Under careful laboratory conditions, researchers have removed almost all kinetic energy from small samples of matter. The temperature of these samples approaches:

(a) 0 K (c) 273 degrees C(b) 0 degrees C (d) -273 degrees F

8. Over time, a gas is cooled until its temperature approaches absolute zero. Which of the following will be true at this temperature?

a) The molecules will collide with the walls of the container.

b) The pressure of the gas will increase dramatically.

c) The gas will not exert pressure on the walls because the molecules will have stopped moving.

d) The kinetic energy of the molecules will remain constant at 20 J.

Exit Slip – Temperature Conversions

1. What is temperature?

2. Are there negative Kelvin temperatures? Why or why not?

3. Convert the following:

0oC = _____K

1500oC = ____K

1200K = _____ oC

100K = _____ oC

Gases - Day 2: The Kinetic-Molecular Theory of GasesBalloon in a Bottle Activity: Complete this activity with a partner. Safety: Only one person may blow up the balloon.

1. Blow up the balloon. Draw a picture and answer the questions in box 1. Is it easy or difficult to blow up the balloon? Why?

2. Put the round part of the balloon inside your 2 L bottle. Roll the neck of the balloon over the mouth of the bottle.

3. Blow up the balloon in a bottle. Draw a picture and answer the questions in box 2. Is it easy or difficult to blow up the balloon? Why?

Box 1: Balloon without a bottle Box 2: Balloon in a bottle

4. What causes the balloon to expand?

______________________________________________________________________________________________________________

5. What happens to air that is trapped in the bottle when you blow into the balloon?

______________________________________________________________________________________________________________________

______________________________________________________________________________________________________

6. Design a modification to the balloon-in-a-bottle that will allow the balloon to inflate. Explain why your design works.

______________________________________________________________________________________________________________________

______________________________________________________________________________________________________

Mini Vocabulary Review: Draw lines matching the words to their definitions.

volume

kinetic energy

pressure

temperature

a measure of the average kinetic energy of the particles in an object.

a measure of the size of an object in three dimensional space.

the energy of an object that is due to the object’s motion.

the amount of force exerted per unit area on a surface.

The Kinetic-Molecular Theory of Gases The Kinetic Molecular Theory is a way to explain the properties of gases by examining the ___________________________________ at the

microscopic level. Gases that obey the Kinetic Molecular Theory are called ____________________________.

The Kinetic-Molecular Theory is based on five rules:

1. Gases consist of _______________________________(molecules or atoms). 2. The particles are TINY compared to the __________________________. So, we do not

count the volume of the particles.

3. The particles are in __________________________________. The particles collide with

the ___________ of the container. These collisions result in

___________________________.

4. The gas particles do not __________________________each other. They move randomly.

5. The average kinetic energy of the gas is ___________________ to the Kelvin temperature.

Draw the gas particles moving in a container here:

Let’s Use the Kinetic-Molecular Theory (KMT) to Explain Properties of Gases: Draw pictures and take notes in the boxes below.

Diffusion – Diffusion is the movement of particles from areas of

_____________________ to _______________________.

Notes from demonstration:

Explain diffusion using the KMT:

Pressure and TemperatureAs temperature increases, pressure __________________.

As temperature decreases, pressure _________________.

Notes from video:

Explain using KMT:

Pressure and VolumeAs volume increases, pressure _________________.

As volume decreases, pressure ________________.

Notes from video:

Explain using KMT:

Pressure and Number of MoleculesAs the number of molecules increases, pressure __________.

As the number of molecules decreases, pressure __________.

Notes from video:

Explain using KMT:

Practice: (1) Fill in the blanks with the term increase or decrease. (2) Explain your answer using the KMT. (3) Draw a before and after picture of

the gas particles in the box to the right.

1. Richard bought a new soccer ball and it came deflated. As he pumps air molecules into the

soccer ball, the pressure inside the soccer ball _____________. Why?

________________________________________________________________________

2. Leslie heated a sealed container with a fixed volume of 4 L over a fire. As the temperature of the

molecules inside the container increased, the pressure in the container ___________________.

Why? __________________________________

_______________________________________________________________________

3. Jonathan rode his bicycle over a nail, putting a hole in the tire which allowed gas molecules to

escape. This caused the pressure inside the tire to _________________. Why?

_______________________________________________________________

________________________________________________________________________

4. Sabrina brought a blown up balloon home from school. She put it in the freezer. As the

temperature of the air in the balloon decreases, the pressure of air in the balloon

__________________. Why? ___________________________________________

____________________________________________________________________

5. Sofia and Natalia climbed Mt. Everest. As they climbed up the mountain, the number of air

molecules around them decreased. This caused the air pressure to ____________. Why?

_____________________________________________________________________________________________________

6. The cylinders in a car engine contain pistons that move up and down in order to increase and

decrease the volume of the cylinders. The cylinders are filled with a fixed amount of gas.

When the piston moves down, decreasing the volume of the cylinder, the pressure inside the

cylinder __________________. Why? ___________________

_____________________________________________________________________

7. In the car engine, when the piston moves up, increasing the volume of the cylinder, the

pressure inside the cylinder _____________. Why? __________________________

____________________________________________________________________

8. Someone farted in Chemistry class. As the smell spreads throughout the room, the number of

natural gas particles around whoever farted ______________. Why?

___________________________________________________________________

Multiple Choice Practice: Circle the best answer.

9. The atmosphere contains many different gases, such as oxygen, carbon dioxide, and nitrogen. Which statement explains why these gases diffuse into each other?

a) Gases have unreactive moleculesb) Gas molecules are close togetherc) Gases have different-sized moleculesd) Gas molecules move in random motion

10. When someone standing at one end of a large room opens a bottle of vinegar, it may take several minutes for a person at the other end of the room to smell it. Gas molecules at room temperature move at very high velocities, so what is responsibvel for the delay in detection of the vinegar?

(a) the increase in the airspace occupied by vinegar molecules(b) the chemical reaction with nerves, which is slower than other sensory processes (c) attractive forces between the air and vinegar molecules(d) random collisions between the air and vinegar molecules

11. The pressure exerted by a gas on a container is caused by the

a) mass of the gas resting against the container.b) gas particles hitting the walls of the container.c) heat flowing from the gas particles into the container.d) potential energy of the gas particles.

12. A sealed, empty plastic soda bottle containing only air was transported from a mountain at an 8250-foot elevation to a city at sea level. The reason why the walls of the soda bottle caved inward at the lower elevation is the

a) sides of the bottle allowed more outside air to diffuse inwardb) concentration of air outside the bottle increasedc) molecule volume of O2 and N2 comprising air decreasedd) warmer air temperature caused air molecules to move slower

13. According to kinetic molecular theory, which picture shows the correct movement of molecules in the balloon?

Activity: Make a poster illustrating one of the practice problems above. Or, make up your own scenario to illustrate. On the poster, describe the scenario, explain whether pressure increases or decreases, and explain why using KMT. Finally, draw a before and after picture.

Challenge Question: A sample of gas occupies 524 mL at a pressure of 1.0 atm. The pressure is increased to 2.0 atm and the temperature is kept constant. The volume decreases to 262 mL. Describe the numeric relationship between the change in pressure and change in volume. Write an algebraic equation to illustrate this relationship.

Name: ______________Period: ____ Date: ______

Exit Slip Standards 4a and 4b

4a: (1) Aerosol cans have a warning not to dispose of them in fires. Why? (use KMT)

(2) As the kinetic energy of molecules increases, the temperature __________. Why?

4b: (3) Why does methane gas (or any gas added to air) diffuse through air? Explain using KMT.

(4) How are molecules of different chemicals arranged when diffusion is complete?

Air Pressure Article: Feeling Pressured?

Earth’s atmosphere, commonly known as air, is a mixture of gases: mainly nitrogen and oxygen. Air pressure is

the force exerted on you by the weight of tiny particles of air (air molecules). Although air molecules are invisible,

they still have mass and take up space. Since there's a lot of "empty" space between air molecules, air can be

compressed to fit in a smaller volume.

When it's compressed, air is said to be "under high pressure". Air at sea level is what we're used to, in fact, we're

so used to it that we forget we're actually feeling air pressure all the time!

Weather forecasters measure air pressure with a barometer. Barometers are used to measure the current air

pressure at a particular location. There are several units of measurement used to measure pressure. The

following table shows some of these units of measurement.

Unit Abbreviation Equivalent in Pascals

Pascal Pa 1

Atmosphere atm 1 atm = 101,325 Pa

1 atm = 760 mm Hg

Millimeter of mercury mm Hg 1 mm Hg = 133.322 Pa

Torr torr 1 torr = 133.322 Pa

*Note: mm Hg and torr are just different names for the same measurement.

How much pressure are you under? Earth's atmosphere is pressing against each square inch of you with a force of

1 kilogram per square centimeter (14.7 pounds per square inch). The force on 1,000 square centimeters (a little

larger than a square foot) is about a ton! In terms of pressure, the atmospheric pressure at sea-level is 1 atm or

760 mm Hg. Why doesn't all that pressure squash me? Remember that you have air inside your body too, that

air balances out the pressure outside so you stay nice and firm and not squishy.

Run for Cover! Air pressure can tell us about what kind of weather to expect as well. If a high pressure system is

on its way, often you can expect cooler temperatures and clear skies. If a low pressure system is coming, then look

for warmer weather, storms and rain.

What Happens if Air Pressure Changes?

Why do my ears pop? If you've ever been to the top of a tall mountain, you may have noticed that your ears pop

and you need to breathe more often than when you're at sea level. As the number of molecules of air around you

decreases, the air pressure decreases. This causes your ears to pop in order to balance the pressure between the

outside and inside of your ear. Since you are breathing fewer molecules of oxygen, you need to breathe faster to

bring the few molecules there are into your lungs to make up for the deficit. As you climb higher, air temperature

decreases. Typically, air temperatures decrease about 3.6° F per 1,000 feet of elevation.

Discussion Questions

1. Do you think a decrease in temperature could be explained in terms of air pressure? How?2. If you were on a mountain, would the weight of the air above you (air pressure) be greater or less than it is now?

Why?3. Why do hot air balloons rise?4. Use the information in the table above to convert the following pressure measurements:

a. 2 atm = ______ torrb. 76.0 atm = _____ mm Hgc. 50,000 Pa = ______ atm

Further Practice: Use your knowledge of the kinetic molecular theory of gases to solve the following problems.

1. What causes a balloon to hold its shape? a) Change of the gas molecules in the containerb) Temperature of the gas molecules in the containerc) Collision of the gas molecules on the containerd) Weight of the gas molecules on the container

2. How do the properties of a gas differ from those of a liquid?

a) Gas molecules have a greater random motion than liquid molecules

b) Gas molecules have less energy than liquid molecules

c) Gas molecules have more mass than liquid molecules.

d) Gas molecules put more pressure on the walls of a container than liquid molecules

3. Which causes the addition of a colored gas to change the color of all of the gas in a container?

a) Temperatureb) Massc) Pressured) Diffusion

4. The volume of 400 mL of chlorine gas at 400mmHg is decreased to 200mL at constant temperature. What is the new gas pressure?

a) 400 mmHgb) 300 mmHgc) 800 mmHgd) 350 mmHge)

5. The air pressure inside a car tire is 100 kPa at a

temperature of 22 °C. When the temperature increases to 37.7 °C, what is the new pressure?

a) 75 kPab) 100 kPac) 32 kPad) 171 kPa

6. If a sealed bag of chips is left in a hot car, what happens to the volume of bag?

a) volume increasesb) volume decreasesc) volume stays the samed) cannot be determined

7. A beach ball has a volume of 2 L at sea level where the pressure is 1.0 atm. You take the

ball to the top of a mountain where pressure is 0.8 atm.

What happens to the volume of the ball?

a) volume increasesb) volume decreasesc) volume stays the samed) cannot be determined

8. What happens to the pressure of the air inside a flask when the flask is heated?

a) pressure increasesb) pressure decreasesc) pressure stays the samed) pressure decreases and then increases

Analyze the following experimental data: A chemist took a fixed volume and quantity of gas and measured the pressure at

different temperatures. Look for a pattern in the data. Can you fill in the missing data?

Temperature (K) 100 200 400 1600

Pressure (atm) 150 300 1200 2400 3000

Justify your answers:

Analyze the following experimental data: A chemist took a fixed quantity of gas at a constant temperature and measured the

pressure at different volumes. Look for a pattern in the data. Can you fill in the missing data?

Volume (L) 20 200 400 800 2000

Pressure (atm) 10,000 1000 500 100 10

Justify your answers:

Name: ___________________________Exit Slip

(1) Mrs. Mawhiney drove over a nail, punching a hole in her tire.

What happened to the air that was in the tire?

Did the air pressure in the tire increase or decrease? Why?

2. Eduardo blew up a balloon so big that it popped. Why did the balloon pop?

Gases 4 – Temperature & Pressure Relationships: Gay-Lussac’s Law

Catalyst: What is air pressure? How do we measure air pressure?

Demonstration: Soda Can Crush. The demonstration shows the relationship between ___________ and ____________.

As temperature increases, pressure ___________________. As temperature decreases, pressure ___________.

Summary of Procedure: (1) A small amount of water (~15 mL) is poured into an empty soda can. (2) The can is heated until steam

comes out and the water boils for about 30 seconds. (3) Then the can is quickly plunged upside down into ice cold water.

Hypothesis: What do you think will happen to the can when it is put into the ice cold water? Why?

Use the space below to draw what you saw, record observations, and explain what happened. Remember to use the kinetic molecular

theory of gases in your explanation.

Drawing Observations Explanations/Questions

Gay-Lussac’s Law: Temperature and Pressure Relationships In 1802, Joseph Gay-Lussac discovered that gas pressure and Kelvin Temperature are ______________________________ at

constant volume. For example, if the absolute temperature (temperature expressed in _____________) is doubled, the pressure is ____________.

If the pressure is cut in half, the absolute temperature is also __________________. When gas volume is held constant, the following equation expresses the pressure and

temperature relationship:

If any three of the variables in the above equation are known, then the unknown fourth

variable can be calculated.

Example 1: P1 = 100 mm Hg, T1 = 50 K,

P2 = ??, T2 = 100 K

Example 2: At 273K, the pressure of a

sample of nitrogen is 1000 atm. What will

the temperature be at 250 atm?

Example 3: At 500K, a 5 L sample of

oxygen has a pressure of 760 torr. If the

temperature doubles, what will the new

pressure be?

1. P1 = 100 mm Hg, T1 = 50 K, P2 = 200

mm Hg, T2 = ??

4. The pressure in a tire is 101 kPa at

283K. What will be the pressure of the tire

at 318K?

7. A sample of gas occupies 1.55 L at

303K. The gas pressure is 300 atm. What

will the temperature be if the pressure is

increased by 100K?

2. P1 = 50 atm, T1 = ??, P2 = 300 atm,

T2= 150 K

5. The pressure in a bottle of soda is 505

kPa at 293K. What is the new pressure if

someone warms the sealed bottle to

338K?

8. A small cylinder of oxygen contains

300.0 mL of gas at 15 atm and 273K.

What will the temperature of the gas be at

60 atm?

3. P1 = 90 torr, T1 = 273 K, P2 = ??, T2 =

2730 K

6. If a gas at 873K exerts a pressure of

1515 mm Hg, at what temperature will the

gas exert 151.5 mm Hg of pressure?

9. A 1.0 L volume of gas at 300K exerts a

pressure of 760 torr. What will the

pressure be at a temperature of 100K?

How do we measure temperature and pressure? (mini-review!)

Temperature Pressure

Celsius °C °C = K - 273 Pascal Pa 1

1000 Pa = 1 kPa

Kelvin K K=°C + 273 Atmosphere atm 1 atm = 101,325 Pa

1 atm = 101.325 kPa

Millimeters of mercury mm Hg 1 atm = 760 mm Hg

torr torr 1 atm = 760 torr

Complete the following conversions. Use the equations and conversion factors in the table.

1. 700°C = ______K

2. 2°C = _____K

3. 500 K = ______°C

4. 35 K = ______°C

5. 1 atm = ______ mm Hg

6. 4 atm = ______ torr

7. 320 mm Hg = ________ atm

8. 1000 Pa = ________ atm

9. 550 torr = ______ mm Hg

10. 100 atm = ______ kPa

What is Standard Temperature and Pressure (also known as STP)? (see pp. 420)

STP stands for ___________________________________________. It is a term used in Chemistry to indicate that an

experiment or measurement was recorded when the temperature was __________ and the air pressure was ________. STP is a

number (or CONDITION) that we can use in calculations that _____________________.

If you see STP (standard temperature and pressure) you should immediately think

0° C (or 273K) and 1 atm (or 760 torr or 760 mm Hg)

Example: A chemist has a 10 L sample of fluorine gas at standard temperature and pressure. If the volume is kept constant and the

temperature is increased to 300K. What is the new pressure?

Further Practice: Complete the following practice problems. Show all your work.

1.) Analyze the following experimental data: A chemist took a fixed volume and quantity of gas and measured the

pressure at different temperatures. Use Gay-Lussac’s Law to fill in the missing data.

Pressure (atm) 10 25 30 50 75 200 400 100

0

Temperatute (K) 15 45 112.

5

150 600 650 200

0

2.) More pressure-temperature problems: Hint: For the following problems, convert from Celsius to Kelvin first. a) At 122°C the pressure of a sample of nitrogen is 1.07 atm. What will the pressure be at 205°C, assuming constant volume?

b) The same sample of nitrogen as in item (a) starts at 122°C and 1.07 atm. After cooling, the pressure is measured to be 0.880 atm. What is the new temperature?

c) A sample of helium gas is at 122 kPa and 22°C. Assuming constant volume, what will the temperature be when the pressure is 203 kPa?

d) The air in a steel-belted tire is at a gauge pressure of 29.8 psi at a temperature of 20°C. After the tire is driven fast on a hot road, the temperature in the tire is 48°C. What is the tire’s new gauge pressure?

Gases 5 – Temperature & Volume Relationships: Charles’s Law

Catalyst: Standard temperature and pressure is 273K and 1 atm. (1) Is standard temperature cold or hot? Explain?

Where could you go to be at standard air pressure?

Video Demo: Egg in a Bottle: What happens to the egg? Why? Use the kinetic molecular theory of gases!

Demonstration: Balloon & Bottle 2. The demonstration shows the relationship between ___________ and ____________.

As temperature increases, volume ___________________. As temperature decreases, volume ___________.

Summary of Procedure: (1) A small amount of water (~15 mL) is poured into an empty Erlenmeyer flask. (2) The flask is heated until

steam comes out and the water boils for about 30 seconds. (3) Then the flask is removed from the heat and a balloon is attached over

the mouth of the flask.

Hypothesis: What do you think will happen to the balloon when we attach it to the flask? What will happen when the gas in the flask

cools down? Why?

Use the space below to draw what you saw, record observations, and explain what happened. Remember to use the kinetic molecular

theory of gases in your explanation.

Drawing Observations Explanations/Questions

Charles’s Law: Temperature and Volume Relationships Around 1800, a French chemist named Jacques Charles discovered that gas volume and absolute temperature are

______________________________ at constant pressure. For example, if the absolute temperature (temperature expressed in _____________) is doubled, the volume is

________________. If the volume is cut in half, the absolute temperature is also __________________. When gas pressure is held constant, the following equation expresses the volume and

temperature relationship:

If any three of the variables in the above equation are known, then the unknown fourth variable can be calculated.

Example 1: V1 = 100 L, T1 = 100 K, V2 = ??, T2 = 200 K

Example 2: At 273K, the volume of a sample of nitrogen is 30 L. What will the temperature be if the volume increases to 300 L?

Example 3: At 500K, a 1000 mL sample is at standard pressure. If the pressure is held constant and the temperature decreases to 5K, what is the new volume in mL?

1. V1 = 40 mL, T1 = 320 K, V2 = 200 mL, T2 = ??

4. At 273K, the volume of a sample of oxygen is 22.4 L. If the pressure is held constant, what will be the volume at 546K?

7. A balloon with a volume of 15.5 L is inflated in a room at 20.0° C and then taken outside where the temperature is

7.0° C. What is the new volume of the balloon? (Convert to Kelvin first!)

2. V1 = 50 L, T1 = ??, V2 = 5 L, T2= 150 K

5. A 160 L sample of helium has a temperature of 300K. If the temperature decreases to 150K, what will the new volume be?

8. If the original temperature of a 62.2 L sample of a gas is 150° C, what is the final temperature of the gas if the new volume is 24.4 L and the pressure remains constant?

3. V1 = 75 mL, T1 = 273 K, V2 = ??, T2 = 2730 K

6. A sample of argon gas has a volume of 360 mL at standard temperature. What is the volume of the gas if the temperature increases to 300K?

9. The volume of gas in a syringe is 15.0 mL at 23.5° C. What will the volume of the gas be at 72.5° C if the pressure is held constant?

Boyle’s Law: Pressure and Volume Relationships In 1662, English scientist Robert Boyle discovered that gas volume and pressure are

_______________________________ at constant temperature. For example, if the pressure is doubled, the volume is __________________. If the

volume is cut in half, the pressure is _________________. When gas temperature is held constant, the following equation expresses the volume and

pressure relationship:

If any three of the variables in the above equation are known, then the unknown fourth variable can be calculated. Hint! Any volume or pressure units may be used as long as they are the same on both sides of the equation.

Example 1: V1 = 100 L, P1 = 100 atm, V2 = ??, P2 = 20 atm

Example 2: A sample of gas occupies 523 mL at 1.00 atm. The pressure is increased to 1.97 atm, while the temperature remains the same. What is the new volume?

Example 3: A sample of gas occupies 100 L at 2.00 atm. The pressure is decreased to 760 mm Hg. What is the new volume?

1. V1 = 40 mL, P1 = 1000 kPa, V2 = 200 mL, P2 = ??

4. Given the volume of a gas as 200 mL at 1.05 atm pressure, calculate the volume of the same gas at 1.01 atm. The temperature is held constant.

7. If 2.5 L of a gas at 110.0 kPa is expanded to 4.0 L at constant temperature what will happen to the pressure? What will be the new value of pressure?

2. V1 = 50 L, P1 = ??, V2 = 5 L, P2= 1500 5. A sample of oxygen gas has a volume 8. If 650 mL of hydrogen is stored in a

atm of 150.0 mL at a pressure of 0.947 atm. What will the volume of the gas be at a pressure of 1.000 atm if the temperature remains constant?

cylinder with a moveable piston at 225 kPa and the pressure is increased to 545 kPa at constant temperature, what is the new volume?

3. V1 = 75 mL, P1 = 760 mm Hg, V2 = ??, P2 = 76,000 mm Hg

6. A sample of gas in a syringe has a volume of 9.66 mL at a pressure of 64.4 kPa. The plunger is depressed until the pressure is 94.6 kPa. What is the new volume, assuming constant temperature?

9. If the volume of a gas is tripled at constant temperature, what will happen to the pressure?

Know Your Units!

Temperature

Standard Temperature = 0°C or 273K

Absolute zero = 0K or -273 °C

K = °C + 273

Volume1 L = 1000 mL

At STP, 1 mol gas = 22.4 L

PressureStandard Pressure = 1 atm, 760 mm Hg

1 atm = 101.325 kPa

1 atm = 760 mm Hg = 760 torr

Mixed Practice Problems: Gas Laws

1. Which change would decrease the pressure exerted by a gas?

a) increasing the volume of the gas’s containerb) adding more gas moleculesc) an increase in the temperature of the gasd) an increase in the kinetic energy of the gas molecules

2. The volume of a balloon is 3.0 liters at sea level where the air pressure is 1.0 atm. If the air pressure drops of 0.75 atm and the temperature remains the same, what is the new volume of the balloon?

a) 2.3 liters c) 3.8 litersb) 3.0 liters d) 4.0 liters 3. A beach ball is inflated to a volume of 2.0 liters at 20°C.

After sitting in the hot sand all day, its temperature has increased to 40°C. What will its volume be at this temperature?

a) 1.0 liters c) 2.3 litersb) 1.5 liters d) 4.0 liters

4. The gases in an aerosol can of hair spray exert a pressure of 3.0 atm at 20°C. When the can is placed in a refrigerator at 10°C, what pressure will be exerted by the gases in the can?

a) 1.5 atm c) 3.1 atmb) 2.9 atm d) 6.0 atm

5. A balloon is inflated to 4.0 liters on a mountain top where the pressure is 0.80 atm. The balloon is then taken down to the seashore, where the pressure 1.0 atm. What is the volume of the balloon at the seashore?

a) 3.2 L c) 4. 8 Lb) 4.0 L d) 5.0 L

6. A gas sample has a volume of 125 mL at 91.0 kPa. What will its volume be at 101 kPa?

7. In a deep-sea station 2.0 x 102 m below the surface, the pressure in the module is 20.0 atm. How many liters of air at sea level are needed to fill the module with 2.00 x 107 L of air?

8. A gas at 65°C occupies 4.22 L. At what Celsius temperature will the volume be 3.87 L, at the same pressure?

9. A sample of hydrogen exerts a pressure of 0.329 atm at 47°C. What will the pressure be at 77°C, assuming constant volume?

10. A sample of ammonia has a volume of 5.0 L at 300K and 1.0 atm. What is the volume of the sample at standard temperature and pressure?

11. When you expand your lungs, air flows in. Why?

12. When you put air in a completely flat bicycle tire, the entire tire expands. Why?

Gas Laws 6: The combined Gas Law and Avogadro’s Law

Catalyst: What gas law was demonstrated by the can crush demonstration? Why?

What gas law was demonstrated by the marshmallow video? Why?

Gas Laws Mini-Review

Gay-Lussac’s Law: At constant volume, pressure and temperature are _________________ proportional.

For example, as pressure increases, temperature __________________.

Charles’s Law: At constant pressure, volume and temperature are ________________ proportional. For example, as

volume increases, temperature ____________________.

Boyle’s Law: At constant temperature, volume and pressure are _______________ proportional. For example, as volume increases,

pressure ___________________.

The Combined Gas Law

The combined gas law combines ________________________, _____________________, and ____________________ into one. If you are given any five of the variables, you can solve for the sixth.

Think Box: Why do we need the combined law? What new situation does it address?

ChemistryName: ____________________________

Period: ______ Date: _______________Example 1: P1=300 torr, P2=900 torr V1=40

L, V2= 10 L, T1=250 KT2=???

Example 2: A cheetos bag is sitting in a car at STP and has a volume of .5 L. Then, the car is heated to 27 °C. The pressure increases to 1.2 atm. What is the bag’s new volume?

Example 3: If a gas at 6 L and 30 torr is compressed to a pressure of 600 torr, what is the new volume of gas?

1. P1=500 torr, P2=1000 torr, V1=?? L, V2= 20 L, T1=200 KT2=100 K

4. A balloon at 200 K is filled with 4 L of He gas at 2 atmospheres. As the balloon is flown through colder air at 100 K, it is compressed to a volume of 1 L. What is the final pressure?

7. A piston filled with 3 liters of gas at 27 degrees Celsius is compressed down to 1 L. What is the final temperature in Celsius? What is the final temperature in Kelvin?

2. P1=2.0 atm, P2=??, V1=3 L, V2= 30 L, T1=200 K T2=100 K

5. 2 Liters of a gas at STP is expanded to 4 Liters and 273 K. What is the final pressure?

8. A balloon at 546 K, 4L, and 2 atm is cooled down to STP. Find the final volume.

2. P1=4.0 atm, P2=16.0 atm, V1=3 L, V2= 30 L, T1=100 K T2=??

6. 30 mL of gas at STP is heated to 50 degrees Celcius and the pressure is changed to 0.5 atm. Now, what is the volume of the gas?

9. A syringe is filled with 8 L of a gas at STP. The temperature is maintained at 273 K and volume is compressed to 4 L. What is the final pressure?

ChemistryName: ____________________________

Period: ______ Date: _______________

Avogadro’s Law: The relationship between number of molecules and volume

In 1811, Italian scientist Amadeo Avogadro found that equal volumes of all gases, under the same conditions, have the _______________________________________________.

Specifically, at standard temperature and pressure, ___________________________________ has a volume of 22.4 L.

Avogadro’s law means that gas volume is ______________________________ to the number of moles of gas at the same temperature and pressure.

Example 1: V1 = 22.4 L, n1 = 1 mol, V2 = ___ , n2 = 5 mol

Example 2: What is the volume of 10 mol of nitrogen gas at STP?

Example 3: 6 mol of ammonia gas has a volume of 120 L. At the same temperature and pressure, what is the volume of 18 mol of ammonia?

1. V1 = 30 L, n1 = 2 mol, V2 = ___ , n2 = 6 mol

3. What volume of carbon dioxide contains the same number of molecules as 20.0 mL of oxygen at the same conditions?

5. 15 mol of hydrogen gas has a volume of 300 L. If temperature and pressure are held constant, how many moles are in 900 L of hydrogen?

2. V1 = 10 L, n1 = 5 mol, V2 = 100 L , n2 = ___ mol

4. A very large balloon holds 224 L of helium gas at STP. If 5 moles of helium are released from the balloon, how many moles of helium remain? What is the new volume of helium?

6. A 140 mL sample of fluorine gas contains 0.7 mol fluorine. At constant temperature and pressure, what is the volume of 4.9 mol fluorine?

ChemistryName: ____________________________

Period: ______ Date: _______________Mixed Practice: Review with resources posted on the class website.

1. Why is it easy to compress a gas?

2. What causes atmospheric pressure?

3. The atmospheric pressure on top of Mount Everest is 58 kPa. What is this pressure in atmospheres?

4. If the volume of a gas decreases by a factor of 10, what will happen to the gas pressure? (Assume temperature is held constant.)

5. A student blows up a balloon in class. Then, the balloon is dipped into a container of liquid nitrogen. Liquid nitrogen has an extremely low temperature. What happened to the gas particles in the balloon?

6. The volume of air in a tire is 2 L at 1.00 atm and 30 °C. If the temperature decreases to standard temperature and the pressure remains constant, what is the new volume?