Unit 5 Gases: Notes Day 1

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

The distance between gas particles is much ______the distance between particles of a liquid or solid.
Applying ______to a gas compresses or pushes the particles closer together.
Unlike solids and liquids, gases ______fill their containers.
Gases have high ______because their particles move more than particles in a solid or liquid.
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:

Practice:

Name: ______

Period: ____ Date: ______

10oC =______K
25oC = ______K
-100oC=______K
400 K=______oC
300K =______oC
350K = ______oC
1000K = ______oC
47K = ______oC
42oC = ______K
850oC = ____

Name: ______

Period: ____ Date: ______

Name: ______

Period: ____ Date: ______

Check Your Understanding: Choose the best answer. When you are done, check with your neighbor. Then, ask to see the answer key.

Name: ______

Period: ____ Date: ______

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

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.

Name: ______

Period: ____ Date: ______

Exit Slip – Temperature Conversions

What is temperature?

Are there negative Kelvin temperatures? Why or why not?

Convert the following:

Name: ______

Period: ____ Date: ______

0oC = _____K

1500oC = ____K

1200K = _____ oC

100K = _____ oC

Gases - Day 2: The Kinetic-Molecular Theory of Gases

Balloon 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.

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 Temperature
As temperature increases, pressure ______.
As temperature decreases, pressure ______.
Notes from video:
Explain using KMT:
Pressure and Volume
As volume increases, pressure ______.
As volume decreases, pressure ______.
Notes from video:
Explain using KMT: / Pressure and Number of Molecules
As 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 molecules

b) Gas molecules are close together

c) Gases have different-sized molecules

d) 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

(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 inward

b) concentration of air outside the bottle increased

c) molecule volume of O2 and N2 comprising air decreased

d) 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