Question

How much heat is needed to convert 10 kg of water at 30◦C to:

(a) water at 100◦C?
(b) steam?
(c) ice?

Take:

Specific heat capacity of water = 4.186 kJ/kg◦C

Latent heat of vaporization of water = 2264 kJ/kg

Latent heat of fusion of water = 333 kJ/kg.

Answer 1

part a )

water from 30 degree to 100 degree

Q = mcdT

m = mass = 10 kg

c = specific heat capacity = 4.186 kJ/kgoC

dT = 100-30 = 70

Q = 10 * 4.186 * 70 = 2930.2 kJ

part b )

water change state after degree

Q = heat given from 30 degree to 100 + phase change heat

Q = mcdT + m*Lv

Lv = latent heat of vaporization = 2264 kJ/kg

Q = 25570.2 kJ

part c ) here water also change state ,goes from liquid to state

Q = mcdT + m*Lf

Lf = latent heat of fusion = 333 kJ/kg

Q = 6260.2 KJ