Question

2.6 kilograms of water are changed (a) from ice at 0?C into liquid water at 0?C and (b) from liquid water at 100?C into steam at 100?C. For each situation, determine the change in mass of the water.

Answer 1

a)

m = mass given = 2.6 kg

L = latent heat of fusion from ice to water = 334000 J/kg

m' = change in mass

c = speed of light = 3 x 10⁸ m/s

using conservation of heat

m' c² = m L

m' (3 x 10⁸)² = (2.6) (334000)

m' = 9.65 x 10^-12 kg

b)

L = latent heat of fusion from water to steam = 2230000 J/kg

m = mass given = 2.6 kg

m' = change in mass

c = speed of light = 3 x 10⁸ m/s

using conservation of heat

m' c² = m L

m'  (3 x 10⁸)² = (2.6) (223000)

m' = 6.44 x 10^-12 kg