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Gas Laws

Unit 2 - States of Matter

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Lesson 5: Questions

  • How do you manipulate the gas law equations to solve for certain variables?

  • What are the relationships between the variables in each gas law equation?

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Vocabulary

Define the following vocabulary words:

  • Direct Relationship
  • Inverse Relationship
  • Boyle’s Law
  • Charles’ Law
  • Lussac’s Law

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Review

Temperature: the motion of the particles within a substance.

Volume: the amount of space a substance occupies.

Pressure: the collisions of the particles in a substance.

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Pressure

Pressure: the collisions of particles in a substance.

  • Tool: Barometer
  • Units: - Atmospheres (atm)

- Kilopascals (Kpa)

- Millimeters of Mercury (mm Hg)

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Gas Laws

Three gas laws that describe the relationship between pressure, volume and temperature.

  1. Boyle's Law
  2. Charles' Law
  3. Lussac's Law

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Boyle's Law

Boyle’s law describes the relationship between volume and pressure. The temperature remains constant (not changing).

Boyle’s Law is an indirect relationship (opposites)

Equation: P1V1 = P2V2

P

V

V

P

An increase in volume (space) results in a decrease in pressure (collisions).

A decrease in volume (space) results in an increase in pressure (collisions).

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Boyle's Law - a change in pressure results in a indirect change in volume

Relationship: indirect

  • Opposites
  • One increases; other

decreases

Equation: P1V1 = P2V2

Pressure: increases

Volume: decreases

Temperature: constant

Pressure: decreases

Volume: increases

Temperature: constant

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Pressure Differential

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Boyle's Law Example

Problem: A container of gas has a volume of 5L and a pressure of 100 kPa. The container is taken up to a high altitude, and the pressure drops to 50 kPa. What will be the volume of the gas at that pressure?

Givens:

P1 =

V1 =

P2 =

V2 =

Equation: P1V1 = P2V2

Work:

Answer (w/ Units):

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Boyle’s Law Video Tutorial

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Charles’ Law

Charles’ law describes the relationship between temperature and volume. The pressure remains constant (not changing).

Charles’ Law is a direct relationship

Equation: V1 = V2

T1 T2

T

An increase in temperature (motion) results in an increase in volume (space).

A decrease in temperature (motion) results in a decrease in volume (space).

T

V

V

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Charles' Law

Relationship: direct

  • Both increase/decrease

together

Equation: V1 = V2

T1 T2

Pressure: constant

Volume: increases

Temperature: increases

Pressure: constant

Volume: decreases

Temperature: decreases

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Charles' Law Example

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Charles' Law Example

Problem: A container of gas has a volume of 2L and a temperature of 300 K. The container is heated to 1200K. What will be the volume of the gas at that temperature?

Givens:

T1 =

V1 =

T2 =

V2 =

Equation: V1 = V2

T1 T2

Work:

Answer (w/ Units):

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Charles’ Law Video Tutorial

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Lussac’s Law

Lussac’s law describes the relationship between temperature and pressure. The volume remains constant (not changing).

Lussac’s Law is a direct relationship

Equation: P1 = P2

T1 T2

T

An increase in temperature (motion) results in an increase in pressure (collsions).

A decrease in temperature (motion) results in a decrease in pressure (collisions).

T

P

P

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Lussac's Law

Relationship: direct

  • Both increase/decrease

together

Equation: P1 = P2

T1 T2

Pressure: increases

Volume: constant

Temperature: increases

Pressure: decreases

Volume: constant

Temperature: decreases

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Lussac's Law Example

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Lussac's Law Example

Problem: A 10L container of gas has a temperature of 500K and a pressure of 100kPa. The container is cooled to 100K. What will be the pressure of the gas at that temperature?

Equation: P1 = P2

T1 T2

Work:

Answer (w/ Units):

Givens:

P1 =

T1 =

P2 =

T2 =

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Lussac's Law Video Tutorial