The change in the internal energy of 3 moles of a gas heated at constant volume from 20^ C to 40^ C is 1080 ~J . The molar specific heat of the gas at constant volume is J mol ⁻¹ K ⁻¹ is.

Step-by-step solution

Change of internal energy at a constant volume is aligned U & =n C_V T C_V & = U n T aligned Here, aligned U & =1080 ~J n & =3 moles T & =40-20=20^ C or 20 ~K aligned Hence, C_V= 1080 3 20 =18 ~J ~mol ⁻¹ ~K ⁻¹ .