Question

At 0°C and 1 atm, heat absorbed by the system by melting of one mole of ice is 6.05 KJ/mol. The molar volume of ice and water are 0.0196 L and 0.0180 L respectively. Calculate ∆H and ∆U.

Answer 1

Heat is absorbed here at constant pressure so ∆H = 1440 cal
∆U can be calculated by : ∆U – ∆H – P∆V
P = 1 atm, ∆V = 0.196L – 0.180L
= 0.0016 L
P∆V = 1 × 0.0016 = 0.0016 L atm
= 0.0016 × 24.217 calories
1 l atm = 24.217 calories
So ∆U = 1440cal – 0.0016 × 24.217 cal
= 1439.96 calories
So ∆H = ∆U