Question

A sample of 0.800 kg of water is held at a temp of 100°C. How much energy must be added to completely turn the liquid water to water vapor?( The latent heat of vaporization for water is 2260 kJ/kg; the latent heat of fusion for water is 333 kJ/kg.)

a. 1810 kJ
b. 266 kJ
c. 256 kJ
d. 2830 kJ

Answer 1

100C = boiling point for water

Use Latent heat (vaporization) equation:

Q = m(Lv)

(Q = Energy needed) (m = mass) (Lv = Latent heat of vaporization)

Substitute:

Q = 0.8(2260)

Solve:

Q = 1808

Energy needed to change water phase from liquid to gas = 1808 kJ of energy