Gas Laws Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Gas Laws.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

A set of mathematical relationships that describe how the pressure, volume, temperature, and amount (moles) of a gas are interconnected.

How gases behave when you squeeze them, heat them, or add more.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: P, V, T, and n are all connected—change one, and others adjust.

Common stuck point: Temperature must always be converted to Kelvin (K = C + 273) before using any gas law formula.

Sense of Study hint: When solving gas law problems, identify which variables change and which are constant. First convert temperature to Kelvin (K = °C + 273). Then choose the correct law: Boyle's (P_1V_1 = P_2V_2 at constant T, n), Charles's (V_1/T_1 = V_2/T_2 at constant P, n), or the combined/ideal gas law for multiple changes. Finally, solve for the unknown and check units.

Worked Examples

Example 1

easy
A gas occupies 2.0\,\text{L} at 1.0\,\text{atm}. What is its volume at 3.0\,\text{atm} (constant temperature)?

Solution

  1. 1
    Use Boyle's Law: P_1V_1 = P_2V_2.
  2. 2
    1.0 \times 2.0 = 3.0 \times V_2.
  3. 3
    V_2 = \frac{2.0}{3.0} = 0.67\,\text{L}.

Answer

V_2 = 0.67\,\text{L}
Boyle's Law states that pressure and volume are inversely proportional at constant temperature. Tripling the pressure reduces the volume to one-third.

Example 2

medium
Use the ideal gas law to find the volume occupied by 2.0 mol of gas at 25°\text{C} and 1.0\,\text{atm}. (R = 0.0821\,\text{L·atm/mol·K})

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
A gas at 200\,\text{K} occupies 4.0\,\text{L}. What volume does it occupy at 400\,\text{K} (constant pressure)?

Example 2

medium
A gas occupies 2.40 L at 1.00 atm. If the pressure increases to 1.50 atm at constant temperature, what is the new volume?
← Back to Gas Laws Formula Explained Practice Mode

Background Knowledge

These ideas may be useful before you work through the harder examples.

moleparticle theory