Question

If the work done by a system on its environment is 100 kJ and the increase in the internal energy the system is 200 kcal, find the heat supplied to the system. Take J - 4186 J/kcal​

Answer 1

As the work is done by the system and heat is supplied to the system.

Therefore,

q=100 cal=420J

w=−300J

Now from first law of thermodynamics,

ΔU=q+W

∴ΔU=420+(−300)

⇒ΔU=120J

Hence the change in internal energy during the process is 120J.