Question

In a process, 701 J of heat is absorbed by a system and 394 J of work is done by the system. What is the change in internal energy for the process?

Answer 1

According to the first law of thermodynamics,
$\Delta U=q+W\left(i\right)$
Where,
$\Delta U$ = change in internal energy for a process q= heat
W = work Given,
q = + 701 J (Since heat is absorbed)
W = –394 J (Since work is done by the system)
Substituting the values in expression (i), we get

ΔU= 701 J + (-394 J) ΔU = 307 J

Hence, the change in internal energy for the given process is 307 J.