137. Solving a chemistry problem

0.002 m3 of helium and 0.002 m3 of argon are mixed at 300 K and 1.013 ∙ 105 n / m2 each. After isothermal mixing, the resulting gas mixture is heated to 600 K at a constant volume. Calculate the total increase in entropy, taking into account that the molar heat capacity of both gases is the same and is equal to Cv (g) = 12.55 J / mol ∙ K.