Gas laws: Boyle's, Charles's and Avogadro's laws sheet4-mark answer frameState Boyle's law, Charles's law and Avogadro's law with their mathematical forms.
How to lay out the answer. Follow the frame, then write it in your own words.
- 1 · Open in one line. The gas laws relate the pressure, volume, temperature and amount of a gas.
- 2 · Boyle's law. At constant temperature, P ∝ 1/V, so PV = constant (P₁V₁ = P₂V₂).
- 3 · Charles's law. At constant pressure, V ∝ T, so V/T = constant, with T in kelvin.
- 4 · Avogadro's law. At constant temperature and pressure, V ∝ n, the number of atoms or molecules.
- 5 · Real-life link. Rising bubbles grow (Boyle); balloons swell in sunlight (Charles).
- 6 · Close in one line. Combining the three laws gives the ideal gas equation, PV = μRT.
Scoring tip: For each law, write what is kept constant, the statement and the formula. Leaving out the 'kept constant' part loses marks.
