If the equilibrium concentrations for X2,Y2 and XY are 1.2×10^3 M,5.83×10^12 M and 8.9×10^2 M respectively, what was the initial concentration X2 before the reaction occured to from XY?

One mole of a gas is expanded from (2 L, 20 atm,300K) to (5 L, 10 atm,320K) against a constant external pressure of 5 atm. The heat capacity of gas is 100 J/K.Then the enthalpy change during the process is (1 L atm ≃ 100 J)

A certain mass of gas is expanded from (1L,10 atm) to (4L,5 atm) against a constant external pressure of 1 atm. If the initial temperature of the gas is 300 K and the heat capacity of the process is 50 J/∘C. Then the enthalpy change during the process is: (1L atm≃100 J).