Question

Find the heat energy required to boil $5kg$ of water if its initial temperature is ${30}^{0}C$. (specific heat of water is $4200JK{g}^{-1}{K}^{-1}$ and boiling point is ${100}^{0}C$).

Answer 1

Step 1: Given data:

Mass of water $m=5Kg$

Initial temperature of water $={30}^{0}C$

Specific heat capacity of water $s=4200JK{g}^{-1}{K}^{-1}$

Boiling point of water $={100}^{0}C$

Step 2: Finding the heat energy required to boil water:

Heat energy required,$Q=m\times s\times ∆T$ .

Where ‘$m$’ is the mass, ‘$s$’ is the specific heat capacity of water, and ‘$∆T$’ is the rise in temperature.

The rise in temperature,$∆T=t_2-t_1$. Where $t_1$ is the initial temperature and $t_2$ is the final temperature.

We know that, $t_1={30}^{0}C$

$t_2={100}^{0}C$

Substituting the values in $Q=m\times s\times ∆T$

$\Rightarrow 5\times 4200\times (100-30)=5\times 4200\times 70=1470000J$

$\Rightarrow 5\times 4200\times 70=1470000J$

$\Rightarrow 1470000J=1470kJ$

Thus, the heat energy required to boil $5kg$ of water is $1470kJ$.