Question

If 1050 kJ of heat is required to raise the temperature of 18kg of a substance from 25°C to
35°C, find the thermal capacity and water equivalent of the substance.​

Answer 1

Given as :

Total amount of heat = Q = 1050  kJ

The mass of substance = m = 18 kg

The initial temperature = $T_1$ = 25°C

The final temperature = $T_2$ = 35°C

To Find :

The thermal capacity of substance

Solution :

Let The thermal capacity of substance = s  J/Kg °C

∵  Amount of heat = mass ×  thermal capacity of substance × change in temperature

i.e  Q = m s ΔT

Or, ΔT = $T_2$ - $T_1$

          = 35°C  -  25°C

          = 10°C

∵    Q = m s ΔT

Or,   1050 kJ = 18 kg ×  s  ×  10°C

Or,  1050 kJ = 180 kg°C ×  s

∴                s = $\dfrac{180}{1050}$

i.e  thermal capacity of substance = 0.17142  kJ/kg°C

Hence, The thermal capacity of substance is 171.42 J/kg°C . Answer