Question

The temperature of 200 g of water decreases from 20 °C to 0 °C in 10 minutes. Calculate

i. the heat lost by the water.

ii. the rate at which the water is losing heat.

iii. the time taken for the water at 0 °C to turn completely into ice.

Answer 1

1.

$Q=cm∆T=16.8~kJ,$

2.

$\dot Q=\frac Qt=28~\frac Js,$

3.

$Q_1=cm∆T+\lambda m=83.6~kJ,$

$t_1=\frac{Q_1}{\dot Q}=49.8~\text{min}.$