Question

104 kJ of work is done on

certain volume of a gas. If the gas releases

125 kJ of heat, calculate the change in

internal energy (in kJ) of the gas.​

Answer 1

$\huge\underline\frak{\fbox{Solution :-}}$

We know from the first law of thermodynamics that ∆U = Q - W

Given, W = 104 kJ. This work is done on the gas, hence we write W = - 104 kJ.

Similarly, the heat is released by the gas

and we write Q = - 125 kJ.

Therefore, from the first law of

thermodynamics, we have,

∆U = |Q| - |W|

∴ ∆U = (125 - 104) = 21 kJ

Answer 2

Step-by-step explanation:

We know from the first law of

thermodynamics that ∆U = Q - W

Given, W = 104 kJ. This work is done on

the gas, hence we write W = - 104 kJ.

Similarly, the heat is released by the gas

and we write Q = - 125 kJ.

Therefore, from the first law of

thermodynamics, we have,

∆U = |Q| - |W|

∴ ∆U = (125 - 104) = 21 kJ