How much heat energy (in megajoules) is needed to convert 7 kilograms of ice at –9°c to water at 0°c? a. 2.13 mj b. 2.48 mj c. 3.09 mj d. 3.26 mj

2471 kJ

Explanation:

The problem can be split into two steps:

1- Calculate the heat energy needed to raise the temperature of the ice from -9 C to 0 C

2- Calculate the heat energy required to melt the ice

Let's solve them separately.

1- The heat energy needed to raise the temperature of the ice from -9 C to 0 C is given by:

where

m=7 kg is the mass of the ice

Cs=2108 J/kgK is the specific heat capacity of ice

is the temperature gain

Substituting into the formula,

2- the heat energy required to melt the ice is given by

where

m=7 kg is the mass of the ice

is the specific latent heat of fusion for ice

Substituting into the formula,

3- So, the total heat energy needed for the entire process is

volts times amps 6 x 0.5 3w