Answer to Question #304096 in General Chemistry for shan

Question

Calculate the amount of heat (joules required) to convert 200 g of ice cubes (0°C) to gas at 100°C

Answer 1

First you have to decide on the processes taking place - how many changes of state are there and how many ‘heating up’ processes.

1. Ice at 0 deg to water at 0 deg (change of state)
2. Water at 0 deg heated to water at 100 deg (heating up)
3. water at 100 deg to water vapour at 100 deg (change of state)

1 and 3 both involve the appropriate latent heat - latent heat of melting (aka latent heat of fusion) and latent heat of vaporisation.

2 involves the specific heat capacity of water

For 1: heat energy = mass * latent of heat of melting (ice)

For 3: similarly, heat energy = mass * latent heat of vaporisation (water)

For 2: heat energy = c * m * change in temperature (c is specific heat of water)