Question

10 Kg of water is pumped to a height of 2 m, the enthalpy is changed by 15 J/Kg, and work done by the motor is 50 J/Kg, assuming system is insulated what is the change in internal energy of water?

(a) 50 J

(b) 100 J

(c) 150 J

(d) 200 J

The question was posed to me in my homework.

I'd like to ask this question from Application of the Energy Balance to Open Systems in chapter Application of Energy Balances in the Absence of Chemical Reactions and Energy Balances: How to Account for Chemical Reaction of Basic Chemical Engineering

Answer 1

The correct answer is (c) 150 J

Easiest explanation: ∆U = Q + W – m (∆H + ∆PE + ∆KE), => ∆U = 0 + 50*10 – 10*(15 + 10*2) = 500 – 350 = 150 J.