Question

What is a change in energy if 18 grams of water is heated from room temperature to 20 degrees above it?

(a) 1.50 KJ

(b) 0.506 KJ

(c) 1.06 KJ

(d) 1.506 KJ

This question was addressed to me during an internship interview.

This intriguing question originated from Thermodynamics in division Thermodynamics of Chemistry – Class 11

Answer 1

Correct answer is (d) 1.506 KJ

Easy explanation: We know that Q = msΔT, where Q is the energy,m is the mass of water, s is the specific heat of water and T is the temperature. So the change in energy required here = 18 g x 4.184 J/g-K x 20K = 1.506KJ.