Question

How much heat energy (in megajoules) is needed to convert 7 kilograms of ice at –9°C to water at 0°C?

A. 3.26 MJ
B. 2.48 MJ
C. 3.09 MJ
D. 2.13 MJ

Answer 1

I think the answer is B. 2.48 MJ, correct me if I’m wrong I’m studying this

Answer 2

The heat required to change the phase of a substance can be calculated by using the formula,

q = mCΔT where q is the heat needed, m is the mass of the substance, C is the specific heat capacity and ΔT is the change in temperature.

q = 7000 g (4.18 J/ g °C) (0°C - (-9°C))
q = 263340 J or .26334 MJ

I think the answer is not given in the choices.