The Gas Laws — Drills · Grade 11 Science

Chapter: States of Matter & Gases

What these drills covers

By the end of The Gas Laws you should be able to:

I can use Boyle's, Charles's, Gay-Lussac's, and the combined gas law to predict how a gas's pressure, volume, and temperature change.
I can convert Celsius to kelvin and explain why gas-law calculations must use the Kelvin scale.

6 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: Boyle's Law, Charles's Law, Gay-Lussac's Law, combined gas law, Kelvin scale, absolute zero, pressure.

Problem 1

At constant temperature, Boyle's Law relates which two quantities?

pressure and volume
volume and moles
pressure and temperature
temperature and volume

Answer and explanation

pressure and volume

Boyle's Law connects pressure and volume (inversely) at constant temperature.

Problem 2

A gas at 2.0 atm occupies 3.0 L. At constant temperature, what is its volume at 6.0 atm?

Answer and explanation

1 L

Boyle's Law: V₂ = P₁V₁/P₂ = (2.0 × 3.0)/6.0 = 1.0 L.

Problem 3

A gas at 250 K occupies 5.0 L. At constant pressure, what volume does it occupy at 500 K?

Answer and explanation

10 L

Charles's Law: V₂ = V₁ × (T₂/T₁) = 5.0 × (500/250) = 10.0 L.

Problem 4

A gas in a rigid container is at 1.5 atm and 200 K. What is its pressure when heated to 400 K?

Answer and explanation

3 atm

Gay-Lussac's Law (constant volume): P₂ = P₁ × (T₂/T₁) = 1.5 × (400/200) = 3.0 atm.

Problem 5

A gas occupies 4.0 L at 1.0 atm and 200 K. Using the combined gas law, what volume does it occupy at 2.0 atm and 300 K?

Answer and explanation

3 L

Combined gas law: V₂ = V₁ × (P₁/P₂) × (T₂/T₁) = 4.0 × (1.0/2.0) × (300/200) = 4.0 × 0.5 × 1.5 = 3.0 L.

Problem 6

A student uses 25°C directly in Charles's Law and gets the wrong answer. What did they do wrong, and what should they have used?

Answer and explanation

They forgot to convert to kelvin. Charles's Law requires absolute temperature, so 25°C must first become 25 + 273 = 298 K. Using the Celsius value gives an incorrect ratio because the Celsius scale does not start at absolute zero.

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