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Gas Laws Worksheet with Answers (Grade 11 Chemistry)

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📄 Gas Laws Worksheet with Answers (Grade 11 Chemistry)

Practise the gas laws with this free Grade 11 chemistry worksheet.

This free gas laws worksheet covers every gas law Grade 11 students need: Boyle's, Charles's, Gay-Lussac's, the combined gas law and the ideal gas law, plus molar volume at STP and SATP.

It starts with kelvin and pressure conversions, builds through each law, and finishes by finding the molar mass of an unknown gas. The answer key shows the full setup for all 22 problems, and every answer has been calculated and checked.

  • Grade 11 Chemistry
  • 28 marks
  • 45–60 minutes
  • Worked answer key

What's in This Gas Laws Worksheet

PartSkill practisedMarks
ATemperature and pressure conversions4
BBoyle's law3
CCharles's law3
DGay-Lussac's law2
ECombined gas law4
FIdeal gas law (moles, volume and mass)6
GMolar volume at STP and SATP2
HSpot the mistake2
IChallenge: molar mass of an unknown gas2

It supports the Ontario Grade 11 chemistry curriculum expectations in the Gases and Atmospheric Chemistry unit.

The Five Gas Laws at a Glance

LawEquationHeld constantWhat it means
Boyle's lawP₁V₁ = P₂V₂TemperaturePressure and volume are inversely related: squeeze a gas and its pressure rises.
Charles's lawV₁/T₁ = V₂/T₂PressureVolume is directly proportional to kelvin temperature: heat a balloon and it expands.
Gay-Lussac's lawP₁/T₁ = P₂/T₂VolumePressure is directly proportional to kelvin temperature: a hot tire has higher pressure.
Combined gas lawP₁V₁/T₁ = P₂V₂/T₂Amount of gasCombines the three laws when P, V and T all change.
Ideal gas lawPV = nRTNothing (single state)Links P, V and T to the number of moles; R = 8.314 kPa·L/(mol·K).

Every problem on this gas laws worksheet starts by deciding which variables change and which stay constant. That choice tells you which law to use. For background, see the gas laws overview on Wikipedia.

Why You Must Use Kelvin

Gas laws are proportional to absolute temperature. Heating a gas from 10 °C to 20 °C does not double its volume, because in kelvin that's only 283.15 K to 293.15 K, an increase of about 3.5%. Question 20 on the worksheet is built around this exact mistake. Always convert first: T(K) = T(°C) + 273.15.

Worked Example: The Combined Gas Law

Question 13: 5.00 L of gas at 100. kPa and 27.0 °C changes to 200. kPa and 127.0 °C. Find the new volume.

  1. Convert temperatures: T₁ = 300.15 K, T₂ = 400.15 K.
  2. Rearrange: V₂ = V₁ × (P₁ ÷ P₂) × (T₂ ÷ T₁).
  3. Substitute: V₂ = 5.00 × (100. ÷ 200.) × (400.15 ÷ 300.15) = 3.33 L.

The pressure doubling halves the volume, and the temperature rise expands it again slightly, so the answer passes a quick sense check. For ideal gas problems involving mass, students will also need the mole conversion worksheet skills.

Gas Laws Practice Problems

These match the gas laws worksheet PDF. Use R = 8.314 kPa·L/(mol·K) and give answers to 3 significant figures.

Part A – Temperature and Pressure Conversions

  1. 25.0 °C = ____ K
  2. −40.0 °C = ____ K
  3. 350. K = ____ °C
  4. 2.50 atm = ____ kPa

Part B – Boyle's Law

  1. A gas occupies 4.00 L at 100. kPa. It is compressed to 2.00 L at constant temperature. Find the new pressure.
  2. 250. mL of gas at 95.0 kPa is compressed until its pressure is 190. kPa. Find the new volume.
  3. A 3.0 L sample of gas at 1.5 atm is squeezed to 4.5 atm. Find the new volume.

Part C – Charles's Law

  1. A 2.00 L balloon at 25.0 °C is heated to 100.0 °C at constant pressure. Find the new volume.
  2. 500. mL of gas at 300. K is cooled to 150. K. Find the new volume.
  3. A 1.50 L balloon at 20.0 °C must expand to 2.00 L. To what temperature (in K and °C) must it be heated?

Part D – Gay-Lussac's Law

  1. A tire is at 220. kPa and 15.0 °C. After driving, it reaches 45.0 °C. Find the new pressure (volume constant).
  2. A sealed can is at 150. kPa and 20.0 °C. At what temperature will the pressure reach 300. kPa?

Part E – Combined Gas Law

  1. 5.00 L of gas at 100. kPa and 27.0 °C is changed to 200. kPa and 127.0 °C. Find the new volume.
  2. 2.50 L of gas at STP (0 °C, 101.325 kPa) is moved to 25.0 °C and 98.0 kPa. Find the new volume.

Part F – Ideal Gas Law

  1. How many moles of gas are in a 10.0 L tank at 200. kPa and 300. K?
  2. What volume do 2.00 mol of gas occupy at 100. kPa and 25.0 °C?
  3. What mass of CO2 is in a 5.00 L container at 150. kPa and 20.0 °C?

Part G – Molar Volume

  1. What volume does 0.500 mol of gas occupy at STP?
  2. How many moles of gas are in 74.4 L at SATP?

Part H – Spot the Mistake

  1. A student heats 2.00 L of gas from 10.0 °C to 20.0 °C and predicts the volume doubles to 4.00 L. Explain the error and correct it.
  2. A student says doubling the pressure on a gas (at constant temperature) doubles its volume. Explain the error and correct it.

Part I – Challenge

  1. 1.00 g of an unknown gas occupies 0.500 L at 100. kPa and 27.0 °C. Find its molar mass.

Gas Laws Worksheet Answer Key

Each answer shows the rearranged formula and substitution. The printable key is at the end of the PDF.

Part A answers (Q1–4)
  1. 25.0 °C = 298 K K
  2. −40.0 °C = 233 K K
  3. 350. K = 76.9 °C °C
  4. 2.50 atm = 253 kPa kPa
Part B answers (Q5–7)
  1. P₂ = P₁V₁ ÷ V₂ = (100. × 4.00) ÷ 2.00 = 200 kPa
  2. V₂ = (95.0 × 250.) ÷ 190. = 125 mL
  3. V₂ = (1.5 × 3.0) ÷ 4.5 = 1.0 L
Part C answers (Q8–10)
  1. V₂ = V₁T₂ ÷ T₁ = 2.00 × 373.15 ÷ 298.15 = 2.50 L
  2. V₂ = 500. × 150. ÷ 300. = 250 mL
  3. T₂ = T₁V₂ ÷ V₁ = 293.15 × 2.00 ÷ 1.50 = 391 K (118 °C)
Part D answers (Q11–12)
  1. P₂ = P₁T₂ ÷ T₁ = 220. × 318.15 ÷ 288.15 = 243 kPa
  2. T₂ = 293.15 × 300. ÷ 150. = 586 K (313 °C)
Part E answers (Q13–14)
  1. V₂ = V₁ × (P₁ ÷ P₂) × (T₂ ÷ T₁) = 5.00 × (100. ÷ 200.) × (400.15 ÷ 300.15) = 3.33 L
  2. V₂ = 2.50 × (101.325 ÷ 98.0) × (298.15 ÷ 273.15) = 2.82 L
Part F answers (Q15–17)
  1. n = PV ÷ RT = (200. × 10.0) ÷ (8.314 × 300.) = 0.802 mol
  2. V = nRT ÷ P = (2.00 × 8.314 × 298.15) ÷ 100. = 49.6 L
  3. n = (150. × 5.00) ÷ (8.314 × 293.15) = 0.308 mol; m = 0.308 × 44.01 = 13.5 g
Part G answers (Q18–19)
  1. V = 0.500 mol × 22.4 L/mol = 11.2 L
  2. n = 74.4 L ÷ 24.8 L/mol = 3.00 mol
Part H answers (Q20–21)
  1. Gas laws need kelvin. 283.15 K → 293.15 K is only a small increase: V₂ = 2.00 × 293.15 ÷ 283.15 = 2.07 L
  2. Boyle’s law is an inverse relationship: doubling the pressure halves the volume.
Part I answer (Q22)
  1. n = (100. × 0.500) ÷ (8.314 × 300.15) = 0.0200 mol; M = 1.00 g ÷ 0.0200 mol = 49.9 g/mol

5 Common Gas Law Mistakes

Part H of the gas laws worksheet targets the first two.

  1. Using °C instead of K. This is the most common error on any gas law problem.
  2. Getting Boyle's law backwards. More pressure means less volume.
  3. Mixing pressure units. Keep P₁ and P₂ in the same unit, and use kPa with R = 8.314.
  4. Using mL with R = 8.314. This R needs volume in litres.
  5. Mixing up STP and SATP. STP is 0 °C and 101.325 kPa (22.4 L/mol); SATP is 25 °C and 100 kPa (24.8 L/mol).

How to Use This Gas Laws Worksheet in Class

  • Day 1: Parts A–D, one law at a time, ideally after a syringe or balloon demonstration.
  • Day 2: Parts E–G with the combined and ideal gas laws.
  • Review: Parts H and I. The molar mass challenge connects gases back to stoichiometry.

To keep practising stoichiometry, try the stoichiometry calculation quiz.

Frequently Asked Questions

Is this gas laws worksheet free?

Yes. The worksheet and its worked answer key are free to download and print as a PDF, with no account needed.

Why do gas law problems use kelvin?

The gas laws are proportional to absolute temperature. Celsius has an arbitrary zero, so doubling a Celsius temperature does not double the energy of the particles. Always add 273.15 before calculating.

When do you use the combined gas law instead of the ideal gas law?

Use the combined gas law when the same gas changes from one set of conditions to another. Use PV = nRT when you need moles or mass at a single set of conditions.

What value of R should I use?

With pressure in kPa and volume in L, R = 8.314 kPa·L/(mol·K). The units of R must match the units in the problem.

What grade is this gas laws worksheet for?

It is written for Grade 11 chemistry and also works as review for introductory college chemistry.

More Free Grade 11 Chemistry Resources

Ready to practise? Download the free gas laws worksheet PDF (use the Download button above), print it double-sided, and keep the answer key pages for marking.

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