Experience Chemistry 09.2.2: Gas Laws (Continued)

Lesson 9.2.2: Gas Laws

Multiple Choice

True or False: Gases can be compressed. 

• True

• False

Multiple Choice

A student inflates a balloon with helium and then places it in the freezer. The student should expect

• the balloon's volume to increase

• the balloon's volume to decrease

• the balloon's moles to increase

• the balloon's moles to decrease

Multiple Choice

What is the formula for Boyle's Law?

• P₁V₁=P₂V₂

• P₁V₁/P₂V₂

• P₁V₂=P₂V₁

• P₁/V₁=P₂/V₂

Multiple Choice

A student measures the pressure and volume of an empty water bottle to be 1.4 atm and 2.3 L. She then decreases the pressure to 0.65 atm. What is the new volume?

• 2.1 L

• 5.0 L

• 8.2 L

• 3.9 L

Multiple Choice

What is the formula of Charles' Law?

• V = T

• VT = VT

• T₁ / V_{1 =} T₂ / V₂

• V₁ / T₁ = V₂ / T₂

Absolute Zero

• Charles observed the volumes different Gases at different temperatures

  • All Gases intersected at -273 °​C

• Lord Kelvin Used this point to describe the Kelvin Temperature scale

  • Intersection point is Absolute Zero

    • The temperature at which all molecular motion stops​

Experience Chemistry | Lesson 9.2.2

Gay-Lussac's Law

• The pressure of a fixed mass of Gas at a constant volume varies directly with the Kelvin Temperature

Experience Chemistry | Lesson 9.2.2

Applying Gay-Lussac's Law

• Gay-Lussac's Law can be applied to cooking with a pressure cooker

  • A pressure cooker keeps the pressure and Volume Constant, allowing the liquid inside to reach a higher temperature​

Experience Chemistry | Lesson 9.2.2

Gay-Lussac's Law Sample Problem 1

• The Gas in a container is at a pressure of 3.00 atm at 25°C. Instructions on the container say not to keep it in a place where the temperature exceeds 52°C. What would the pressure of the gas be at 52°C?

  • Step 1: Identify what we have​

    • P₁=

    • T₁=

    • P₂=

    • T₂=

Experience Chemistry | Lesson 9.2.2

Gay-Lussac's Law Sample Problem 1

• The Gas in a container is at a pressure of 3.00 atm at 25°C. Instructions on the container say not to keep it in a place where the temperature exceeds 52°C. What would the pressure of the gas be at 52°C?

  • Step 1: Identify what we have​

    • P₁= 3.00 atm

    • T₁= 25 + 273=298K

    • P₂= ??

    • T₂= 52 + 273 = 325K

  • Step 2: Plug those numbers directly into Gay-Lussac's Law

Experience Chemistry | Lesson 9.2.2

Gay-Lussac's Law Sample Problem 2

• At 120°C, the pressure of a sample of nitrogen is 1.07 atm. What will the pressure be at 205°C, assuming constant Volume?

  • Step 1: Identify what we have​

    • P₁=

    • T₁=

    • P₂=

    • T₂=

Experience Chemistry | Lesson 9.2.2

Gay-Lussac's Law Sample Problem 2

• At 120°C, the pressure of a sample of nitrogen is 1.07 atm. What will the pressure be at 205°C, assuming constant Volume?

  • Step 1: Identify what we have​

    • P₁=1.07

    • T₁=120+273=393K

    • P₂=?

    • T₂= 478 K

Experience Chemistry | Lesson 9.2.2

Combined Gas Law

• Expresses the relationship between pressure, volume, and temperature when the amount of gas is held constant

  • Usually these values are not constant, so you use this law in those situations​

  • Combines all three previous gas laws into one equation

Experience Chemistry | Lesson 9.2.2

Combined Gas Law

• A helium balloon has a volume of 50.0 L at 25°C and 1.08 atm. What Volume will it have at 0.855 atm and 10°C?

  • Step one Identify all the information we have

    • V₁=

    • P₁=

    • T₁=

    • V₂=

    • P₂=

    • T₂=​

    ​

Experience Chemistry | Lesson 9.2.2

Combined Gas Law

• A helium balloon has a volume of 50.0 L at 25°C and 1.08 atm. What Volume will it have at 0.855 atm and 10°C?

  • Step one Identify all the information we have

    • V₁= 50.0

    • P₁=1.08

    • T₁=298

    • V₂=

    • P₂=0.855

    • T₂=​283

  • Step 2: Plug in our values to solve

    ​

Experience Chemistry | Lesson 9.2.2

Combined Gas Law

• The volume of a gas at 27°C and 0.2 atm is 80 mL. What Volume will it have at standard conditions?

  • Step one Identify all the information we have

    • V₁=

    • P₁=

    • T₁=

    • V₂=

    • P₂=

    • T₂=​

    ​

Experience Chemistry | Lesson 9.2.2

Combined Gas Law

• The volume of a gas at 27°C and 0.2 atm is 80 mL. What Volume will it have at STP conditions?

  • Step one Identify all the information we have

    • V₁= 80

    • P₁=0.2

    • T₁= 27 + 273 = 300 K

    • V₂=

    • P₂= 1 atm

    • T₂=​ 0 + 273= 273 K

  • Step two: Plug in your values and solve

Experience Chemistry | Lesson 9.2.2

Avogadro's Law

• 1811: Amedeo Avogadro hypothosized that any two samples of gas will have the same volume when they are held at the same pressure and temperature

  • Samples with the same number of moles have the same volume

  • Simplified: At STP 1 mol of gas = 22.4 L​

Experience Chemistry | Lesson 9.2.2

Avogadro's Law Sample Problem

• What Volume does 0.0685 mol of gas occupy at STP?

  • Step one: convert moles of gas to liters​

Experience Chemistry | Lesson 9.2.2