Question

How much energy is required to change a 35-g ice cube from ice at

−30°C

to steam at 130°C?
1 MJ

Answer 1

We can break this up into 5 stages.
Stage 1 = Heating the ice to 0 degrees.
Stage 2 = Melting the ice.
Stage 3 = Heating the water to 100 degrees.
Stage 4 = Turning the water into steam.
Stage 5 = Heating the steam to 130 degrees.
The energy required is as follows:
Stage 1 = (.030kg)(2090 J/kgC)(30C) = 1881J
Stage 2 = (.030kg)(3.33 x 10^5 J/kg) = 9990J
Stage 3 = (.030kg)(4186 JkgC)(130C) = 16325.4J
Stage 4 = (.030kg)(2.26 x 10^6 J/kg) = 67800J
Stage 5 = (.030kg)(2010 J/kgC)(30C) = 1809J
Adding all these up gives a total energy of 97.805.4J