How much energy (in megajoules) is given up by 0.75 kg of water at 0°C when it freezes to form ice at 0°C?

Correct answer: Q = E = 0.251 MJ

Explanation:

The transition from a liquid aggregate state to a solid crystalline one is called a phase transition.

The expression for the amount of phase transition heat or energy released in this case is:

Q = E = λ · m

Where λ is the specific heat of the phase transition and m is the mass of the liquid.

You should have offered that data for λ but well, that information is well known for ice at normal atmospheric pressure λ = 3.35 10⁵ J/kg

Q = E = 3.35 10⁵ · 0.75 = 2.51 10⁵ J = 0.251 10⁶ J = 0.251 MJ

Q = E = 0.251 MJ

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