The value of E for a system that performs 120 kJ of work on its surroundings and gains 50 kJ of heat is __________.

 

According to first law of thermodynamics :

Q = ?E + W

ΔE = Q - W

Where

E = change in internal energy = ?

Q = heat = 50 KJ Since it releases heat to the surroundings takes -ve sign

W = work done = +120 KJ Since work is done by the system.

Then, ΔE =50 KJ - 120 KJ = - 70 KJ

Step-by-step explanation

first law of thermodynamics: states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system.

internal energy: the sum of the kinetic and potential energies of a system's atoms and molecules.