Question

find the external workdone by the system in Kcal, when 12.5kcal of heat is supplied to the system and the corresponding increasing in internal energy is 10500J

Answer 1

According to 1st law of thermodynamics

we know that

dU = q + W

so, put it

8.4 KJ = (20 × 4.2 KJ) + W

Work done  = 8.4 kJ - 84 kJ

Work done = -75.6 kJ

i hope that are useful

W = -75.6 BY 4.2 =

-18 kcal