A cylinder fitted with a frictionless piston contains a mixture of oxygen and helium…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A cylinder fitted with a frictionless piston contains a mixture of oxygen and helium gases at 300K and a total pressure of 1.013×105Pa. The partial pressure of oxygen is found to be 0.202×105Pa.
(a) Calculate the mole fraction of each gas in the mixture.
(b) If the total volume of the gas mixture is 5.00L, determine the total number of molecules present.
(c) The piston is slowly moved outward keeping the temperature constant until the total number of molecules doubles while maintaining the same mole fraction ratio. Find the new volume.
(d) Explain briefly why the mole fractions remain unchanged during this operation.