Ideal gasesAQA A-Level Physics: Mind map

Exam questions on Ideal gases

1. A rigid sealed cylinder of volume 2.0 × 10⁻² m³ contains 0.80 mol of an ideal gas at a temperature of 300 K (27 °C). The molar gas constant is 8.31 J mol⁻¹ K⁻¹ and the Avogadro constant is 6.02 × 10²³ mol⁻¹.
   Calculate the number of molecules of gas in the cylinder.2 marks
2. A student investigates a fixed mass of dry air trapped in a glass tube by a short thread of oil. In the first experiment the pressure on the air is varied using a pump while the temperature is kept constant. In the second experiment the tube is heated in a water bath at atmospheric pressure.
   In the first experiment, the student waits for a short time after changing the pressure before each reading of the volume. Explain why.2 marks
3. A gas is trapped in a cylinder by a frictionless piston and kept at a constant pressure of 1.0 × 10⁵ Pa. Its initial volume is 2.0 × 10⁻³ m³ at a temperature of 290 K. The gas is heated slowly until its volume is 5.0 × 10⁻³ m³. Treat the gas as ideal, with $R$ = 8.31 J mol⁻¹ K⁻¹.
   Calculate the work done by the gas as it expands.3 marks