Experience Chemistry Lesson 9.2.1: Gas Laws

​Lesson 9.2.1: The Gas Laws

The Kelvin Temperature scale is used when working with gas laws

• Convert from Celsius by adding 273 to your temperature

  • 0 ° C = 273 K

  • 100 ° C = 373 K

Gases also tend to be studied under Standard Temperature and Pressure Conditions (STP)

• 1 atm Pressure

• ​0 ° Celsius

​

Note for Gas Law Equations

​

Boyle's Law

• Discovered by Robert Boyle

• When the temperature and number of particles are held constant, the volume varies inversely with the pressure.

  • As Volume increases, pressures decreases​

• P₁ ×​ V₁ = P₂ × V₂

  • The units for Pressure and volume don't matter as long as they are the same on both sides of the equation!​

Experience Chemistry | Lesson 9.2 Part 1

Boyle's Law Sample Problem 1

• A Ballon Contains 30.0 L of Helium gas at a pressure of 103 kPa. What is the volume of the helium when the balloon rises to an altitude where the pressure is only 25.0 kPa (assume the temperature is constant)

  • Step 1​: Identify the knowns

    • V₁= 30 L

    • P₁₌ 103 kPa

    • V₂ =?

    • P₂=25 kPa

  • Step 2: Plug your numbers into the equation

    • 30 x 103 = 25 x V₂

    • V₂= (30 x 103) / 25

Experience Chemistry | Lesson 9.2 Part 1

Boyle's Law Sample Problem 2

• A gas with a volume of 4.00 L at a pressure of 205 kPa is allowed to expand to a volume of 12.0 L. What is the pressure in the container if the temperature remains constant?

  • Step 1​: Identify the knowns

    • V₁=

    • P₁₌

    • V₂ =

    • P₂=

  • Step 2: Plug your numbers into the equation

Experience Chemistry | Lesson 9.2 Part 1

Boyle's Law Sample Problem 2

• A gas with a volume of 4.00 L at a pressure of 205 kPa is allowed to expand to a volume of 12.0 L. What is the pressure in the container if the temperature remains constant?

  • Step 1​: Identify the knowns

    • V₁= 4.00 L

    • P₁₌ 205 kPa

    • V₂ = 12.0 L

    • P₂= ?

  • Step 2: Plug your numbers into the equation

    • 4 x 205 = 12 x P₂

    • P₂₌ (4 x 205)/12

Experience Chemistry | Lesson 9.2 Part 1

Boyle's Law Sample Problem 3

• A Sample of Oxygen Gas has a Volume of 150.0 mL when its Pressure is 0.947 atm. What will the volume of the gas be at 0.987 atm if the volume of the gas remains constant?

  • Identify what we have

    • V₁=

    • P₁=

    • V₂ =

    • P₂ =

Experience Chemistry | Lesson 9.2 Part 1

Boyle's Law Sample Problem 3

• A Sample of Oxygen Gas has a Volume of 150.0 mL when its Pressure is 0.947 atm. What will the volume of the gas be at 0.987 atm if the volume of the gas remains constant?

  • Identify what we have

    • V₁= 150

    • P₁=0.947

    • V₂ = ?

    • P₂ =0.987

  • Plug our Values into Boyle's Law

    • 150 x 0.947 = V₂ x 0.987 ​

Experience Chemistry | Lesson 9.2 Part 1

Charles's Law

Experience Chemistry | Lesson 9.2 Part 1

Charles's Law Sample Problem 1

Experience Chemistry | Lesson 9.2 Part 1

​A Sample of neon Gas occupies a volume of 752 mL at 25° C. What will the Volume be at 50° C if the pressure remains constant?

• Step 1: Identify what we know

  • V₁= 752 mL

  • T₁= 25°​C

  • V₂=?

  • T₂= 50°C

Charles's Law Sample Problem 1

Experience Chemistry | Lesson 9.2 Part 1

​A Sample of neon Gas occupies a volume of 752 mL at 25° C. What will the Volume be at 50° C if the pressure remains constant?

• Step 1: Identify what we know

  • V₁= 752 mL

  • T₁= 25°​C

  • V₂=?

  • T₂= 50°C

• Step 2 Change Temperatures to Kelvin

  • T₁= 25 + 273

  • T₂= 50 + 273

Charles's Law Sample Problem 1

Experience Chemistry | Lesson 9.2 Part 1

​A Sample of neon Gas occupies a volume of 752 mL at 25° C. What will the Volume be at 50° C if the pressure remains constant?

• Step 1: Identify what we know

  • V₁= 752 mL

  • T₁= 25°​C

  • V₂=?

  • T₂= 50°C

• Step 2 Change Temperatures to Kelvin

• Step 3: Plug Values into our Equation and solve for our unknown

Charles's Law Sample Problem 2

Experience Chemistry | Lesson 9.2 Part 1

• A balloon filled with Oxygen gas occupies a volume of 5.5 L at 25°C. What Volume will the balloon be at 100°C?

  • Identify what we know

    • V₁= 5.5 L

    • T₁= 25°​C + 273 = 298

    • V₂=?

    • T₂= 100°C+273 =373 K

  • Step 3: Plug Values into our Equation and solve for our unknown