vocabulary: solid liquid gas kinetic molecular theory kinetic energy kelvin degrees celsius torr mm...

Vocabulary:SolidLiquidGasKinetic Molecular TheoryKinetic energyKelvinDegrees CelsiusTorrmm Hg PascalsAtmospheresPressure Vapor PressurePhase Diagram (Triple Point)Boyle’s lawAbsolute zero

Charles’s lawGay-Lussac’s LawCombined gas lawAvogadro’s principleIdeal gas constant (R)Ideal gas lawIdeal gasReal gasPartial Pressures

Objectives:1. Differentiate between types

of phases 2. Convert between Celsius

and Kelvin3. Describe the relationship

between pressure and boiling point

4. Explain and Decipher a phase diagram.

5. State the relationships among pressure, temperature, and volume of a constant amount of gas.

6. Apply the gas laws to problems using pressure, temperature, and volume of a constant amount of gas.

7. Relate number of particles and volume using Avogadro’s principle.

8. Relate the amount of gas present to its pressure, temperature, and volume using the ideal gas law.

9. Compare the properties of real and ideal gases.

10. Use the Law of Partial Pressures to determine the pressure of a gas.

Kinetic Molecular TheoryThe kinetic theory is how particles move.

It states that particles in all forms of matter, (S, L, G), are in constant motion, (either “vibrating”, “sliding”, or “flying”.)

3 Assumptions of Kinetic Molecular Theory3 assumptions of the kinetic theory as it applies to gases:

1. Gases are composed of small particles.

2. These particles are in constant motion and collide with other particles. They will move in a straight path until

force is applied.

3. When particles collide, kinetic energy, (K.E.), is conserved. K.E. is the energy in motion. These types of collisions are called “perfect elastic.”

• If you could play pool using gas particles, they would never stop bouncing around the pool table!

How Temperature Affects the Kinetic Energy of a Gas• The higher the temperature the faster the particles

move. (Direct Relationship: As Temperature increases, K.E. increases.)

• At 0K, which is absolute zero, kinetic energy is also zero. Thismeans there is not motion and everything stops.

• Doubling the Kelvin temperature would double the K.E. (Twice as hot means twice the Kelvin.)

• Proof that gas particle collisions conserve K.E. is that the room is not slowly getting colder!

Temp.

Kinetic Energy

Kelvin Temperature Conversion

ºC +273 = Kelvin

Practice Problems: 1. What Kelvin temperature is the freezing point of water, 0˚C?

2. What is 90 K in degrees Celsius.

3. Which phase of water has the highest K.E.? Lowest K.E? ___

Gas PressureWhen a gas particle collides with an object, it exerts a small force. The result of simultaneous collisions from billions of gas particles upon an object causes gas pressure.

How to Measure Air Pressure

• A barometer is the instrument used to measure air pressure.

• There are 2 types of barometers:

Mercury Barometers:

TED talk for barometers

Mercury Barometer

Gas Pressure Conversion FactorsThe S.I. (metric) unit for pressure is the pascal, (Pa). This is to 1 N/m2

-The standard air pressure (at sea level) is about 1.013 X105 Pascals.

-All of the following pressures are also equal to standard pressure:1 atmosphere (atm) = 760 mm Hg = 101.3 kPa =

1.013 bars=760 Torr= 29.92 inches Hg =14.7 (psi)

Practice Problem: The pressure on top of Mt. Everest is 253 mm Hg. What is this pressure in units of atm, and inches of Hg?

How Altitude Affects Air Pressure

The higher up you go the less air molecules there are, so there are fewer collisions which will cause less pressure.

Inverse Relationship: As altitude inc., pressure dec.

*Examples: This is the reason why your ears pop in elevators, planes, or driving up and down large hills. (Going deep under the water will also cause your ears to pop because of increasing water pressure.)

Altitude

Air Pressure

Air Pressure Crushing Cans

http://www.csun.edu/scied/4-discrpeant-event/the_can_crush/index.htm

Air Pressure Crushing “Cans”

Air Pressure Crushing “Cans”

Dynamic EquilibriumA dynamic equilibrium can be defined as a movement of an equal # of particles back and forth from one state of matter to another.

-To be in equilibrium, the rate of one phase change must equal the rate of another phase change. a. Open Container- NOT at equilibrium(b) Closed Container -that is at equilibrium between the liquid and vapor phases.The rate of evaporation equals the rate of condensation.

How Temperature Affects the Vapor PressureVapor Pressure is the push of a gas above its liquid.

-As the temperature of a liquid increases, so does the number of vapor particles.- More vapor particles cause more collisions

therefore more vapor pressure. Direct Relationship: (Temp ↑ Vapor Pressure ↑)

a. Measuring vapor of a liquid by using a simple barometer. b. The water vapor pushed the mercury level down. c. Diethyl ether shows a higher vapor pressure than water.

3 Ways to Make Water Boil by making Pressures Equal1. Heat it up. Raising the temperature of the water will increase the vapor pressure until it equals the atmospheric pressure.

2. Vacuum Pump: Lower the external pressure above the liquid by removing the air until the atmospheric pressure is equal to the vapor pressure of the water.

3. Combination of 1&2: Lower the air pressure and heat it

“Normal Boiling Point” of Water• At standard pressure, water’s normal B.P = 100˚C. • Once a liquid is boiling, adding heat DOES NOT

increase its temperature. The liquid simply bubbles more.

• On a mountain, the atm. pressure is lower , therefore the temperature at which the water boils is less than 100˚C.

•Foods in boiling water on a mountain will take longer to cook since the boiling water is cooler. (Some foods, like breads and cakes, have special cooking instructions for high altitudes.

Boiling Water Above 100 ºCIn a pressure cooker, the atm. pressure is higher, therefore the temperature at which the water boils is more than 100˚C. Foods in a pressure cooker will cook faster since the water is hotter.• Water that’s next to volcanic vents on the ocean’s floor

will reach temperatures well above 100˚ C, but it won’t “boil” since the surrounding pressure is so high!

Boiling Points vs. Pressure

Practice Problems:

1. What is the normal boiling point for ethanoic acid?

2. At what temperature will ethanoic acid boil on Mt. Everest when the pressure is only 30 kPa?

Names of the Phase Changes

Solid

LiquidGas

Solid→aq = dissolving aq → Solid = crystallizing

Phase DiagramsA phase diagram Shows the relationship between the 3 phases of matter at various temperatures and pressures.

Triple Point: All 3 phases of matter at equilibrium Critical Point: The highest temp. at which the liquid phase can exist.

Phase Diagrams of H2O and CO2

For water, the triple point occurs at 0.01˚C and 4.58 Torr

Boyle's Law

• Boyle’s law states that the volume of a fixed amount of gas held at a constant temperature varies inversely with the pressure.

P1V1 = P2V2 where P = pressure and V = volume

Charles's Law

• As temperature increases, so does the volume of gas when the amount of gas and pressure do not change.

• Kinetic-molecular theory explains this property.

Charles's Law

Charles's Law• Absolute zero is zero on the Kelvin scale.

• Charles’s law states that the volume of a given amount of gas is directly proportional to its kelvin temperature at constant pressure.

Gay-Lussac's Law

• Gay-Lussac’s law states that the pressure of a fixed amount of gas varies directly with the kelvin temperature when the volume remains constant.

Gay-Lussac's Law

The Combined Gas Law

• The combined gas law states the relationship among pressure, temperature, and volume of a fixed amount of gas.

The Combined Gas Law

Practice Problems: 1) 80.0 mL of helium is in a balloon at 25˚C. What will the new volume of the balloon be if the temp. is raised to 100˚C? (Since pressure is not mentioned, it can be assumed that it was constant. You can thrown it out of our equation.)

Practice Problems:2. A rigid steel container is filled with neon under a pressure of 760 mm Hg and a temperature of 325 K. If the temperature is reduced to standard temperature, what will the new pressure be?

3. A balloon at a pressure of 4.5 atmospheres, 300 K, and a volume of 35.0 liters is changed to STP conditions. What will the new volume of the balloon become?

Avogadro's Principle

• Avogadro’s principle states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles.

Avogadro's Principle• The molar volume of a gas is the volume 1 mol

occupies at 0.00°C and 1.00 atm of pressure.

• 0.00°C and 1.00 atm are called standard temperature and pressure (STP).

• At STP, 1 mol of gas occupies 22.4 L.

The Ideal Gas Law• Ideal gas particles occupy a negligible volume and are

far enough apart to exert minimal attractive or repulsive forces on each other.

• Combined gas law to ideal gas law

The Ideal Gas Law• The ideal gas constant is represented by R and is

0.0821 L•atm/mol•K when pressure is in atmospheres.

• The ideal gas law describes the physical behavior of an ideal gas in terms of pressure, volume, temperature, and amount.

The Ideal Gas Law

Practice Problems: 1) 6.5 moles of a gas has a pressure of 1.30 atmospheres and it has a temperature of 20˚Celsius. What is the volume of the gas?

2) How many moles of gas are there in a 7.3 liter balloon with a pressure of 847 mm Hg and temperature of 395 K?

Real Versus Ideal Gases• Ideal gases follow the assumptions of the kinetic-

molecular theory.

• Ideal gases experience:

– There are no intermolecular attractive or repulsive forces between particles or with their containers.

– The particles are in constant random motion.

– Collisions are perfectly elastic.

– No gas is truly ideal, but most behave as ideal gases at a wide range of temperatures and pressures.

Real Versus Ideal Gases (cont.)

• Real gases deviate most from ideal gases at high pressures and low temperatures.

• Polar molecules have larger attractive forces between particles.

• Polar gases do not behave as ideal gases.

• Large nonpolar gas particles occupy more space and deviate more from ideal gases.

Gas Pressure (cont.)

• Dalton’s law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the pressures of all the gases of the mixture.

• The partial pressure of a gas depends on the number of moles, size of the container, and temperature and is independent of the type of gas.

Gas Pressure (cont.)

Ptotal = P1 + P2 + P3 +...Pn

• Partial pressure can be used to calculate the amount of gas produced in a chemical reaction.

Dalton’s Law of Partial Pressure

P(total)= P1+P2+P3…

Practice Problem: A container has oxygen, nitrogen, and helium in it. The total pressure of the container is 2.4 atm. If all of the partial pressures are the equal to one another, what are the partial pressures of the gases?

A. A

B. B

C. C

D. D0% 0%0%0%

Section 13.1 Assessment

Boyle’s Law explains which relationship of properties in gases?

A. pressure and volume

B. amount and pressure

C. temperature and volume

D. volume and temperature

A. A

B. B

C. C

D. D0% 0%0%0%

Section 13.1 Assessment

Atoms are in their lowest energy state at what temperature?

A. 0° Celsius

B. 0° Fahrenheit

C. –100° Celsius

D. 0 kelvin

A. A

B. B

C. C

D. D0% 0%0%0%

Section 13.2 Assessment

Which of the following is NOT one of the related physical properties described in the ideal gas law?

A. pressure

B. volume

C. density

D. temperature

A. A

B. B

C. C

D. D

Section 13.2 Assessment

0% 0%0%0%

3.00 mol of O2 at STP occupies how much volume?

A. 30.0 L

B. 22.4 L

C. 25.4 L

D. 67.2 L

Section 13.1 The Gas Laws

Key Concepts

• Boyle’s law states that the volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature.

P1V1 = P2V2

• Charles’s law states that the volume of a fixed amount of gas is directly proportional to its kelvin temperature at constant pressure.

Section 13.1 The Gas Laws (cont.)

Key Concepts

• Gay-Lussac’s law states that the pressure of a fixed amount of gas is directly proportional to its kelvin temperature at constant volume.

• The combined gas law relates pressure, temperature, and volume in a single statement.

Section 13.2 The Ideal Gas Law

Key Concepts

• Avogadro’s principle states that equal volumes of gases at the same pressure and temperature contain equal numbers of particles.

• The ideal gas law relates the amount of a gas present to its pressure, temperature, and volume.

PV = nRT

A. A

B. B

C. C

D. D0% 0%0%0%

What does the combined gas law relate?

A. pressure and temperature

B. volume and pressure

C. pressure, temperature, and volume

D. pressure, temperature, volume, and amount

A. A

B. B

C. C

D. D0% 0%0%0%

According to Charles’s law, if pressure and amount of a gas are fixed, what will happen as volume is increased?

A. Temperature will decrease.

B. Temperature will increase.

C. Mass will increase.

D. Mass will decrease.

A. A

B. B

C. C

D. D0% 0%0%0%

Equal volumes of gases at the same temperature and pressure contain equal numbers of particles is stated by:

A. Law of conservation of mass

B. Boyle’s law

C. Avogadro’s principle

D. Ideal gas law

A. A

B. B

C. C

D. D0% 0%0%0%

What is the volume of 1.00 mol of chlorine gas at standard temperature and pressure?

A. 1.00 L

B. 18.0 L

C. 22.4 L

D. 44.8 L

A. A

B. B

C. C

D. D0% 0%0%0%

When do real gases behave differently than ideal gases?

A. high temperature or low pressure

B. high temperature or high pressure

C. low temperature or low pressure

D. low temperature or high pressure

A. A

B. B

C. C

D. D0% 0%0%0%

If two variables are directly proportional, what happens to the value of one as the other decreases?

A. increases

B. decreases

C. remains constant

D. none of the above

A. A

B. B

C. C

D. D0% 0%0%0%

What conditions represent standard temperature and pressure?

A. 0.00°C and 0.00atm

B. 1.00°C and 1.00atm

C. 0.00°F and 1.00atm

D. 0.00°C and 1.00atm

A. A

B. B

C. C

D. D0% 0%0%0%

One mole of gas occupies how much volume at STP?

A. 1.00 L

B. 2.20 L

C. 22.4 L

D. 33.7 L

A. A

B. B

C. C

D. D0% 0%0%0%

Which of the following would deviate the most from an ideal gas?

A. gas in a hot-air balloon

B. water vapor from the reaction of gaseous hydrogen and oxygen

C. upper atmospheric gases

D. gases near absolute zero

A. A

B. B

C. C

D. D0% 0%0%0%

What volume will 3.50 mol of Xe gas occupy at STP?

A. 78.4 L

B. 22.4 L

C. 25.9 L

D. 54.4 L