Question

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

Answer 1

ice|-9°c---->ice| 0°c ----> water|0°c
u need the latent heat value of ice and the specific heat capacity of Ice
SHC of ice = 2.108 kJ/kgK = 2108jkg-¹k-¹
latent heat of ice = 334j
so you have
H = mcΔ + mL
H= [7×2108×9] + (7×334)
H= 132804 + 2338
H= 135142 joules
H = 0.135Mj