Calculate the number of kilojoules to warm 125 g of iron from 23.5 degrees C to 78 degrees C

The heat capacity of iron is 0.45J/g°C.

We calculate the heat using the equation:

ΔH = m cp ΔT

where

m is the mass

ΔH is enthalphy or the heat required

cp is the heat capacity

ΔT is the change in temperature

So,

ΔH = m cp ΔT = (125g) (0.45 J/g °C) (75°C - 23.5 °C)

ΔH = 2896.875 J

Dividing by 1000 to convert to kJ,

ΔH = 2.897 kJ