Question

How much heat energy is required to change 2 kg of ice at 0${}^{\circ }C$ in water at 20${}^{\circ }C$.

Answer 1

Total heat = Heat required to convert $2kg$ of ice to $2kg$ of water at $0℃$ +Heat required to convert $2kg$ of water at $0℃$ to $2kg$ of water at $20℃$

Heat$=mhfg+mCp$\Delta t$

Here, $m$(mass of ice)=$2kg$

$hfg$(latent heat of fusion of ice)=$334$kJ

$Cp$ of water(specific heat)=$4.187$ kJ/kg-k

$\Delta t$(temperature difference) =$20℃$

Therefore,

Heat required$=2\times 334+2\times 4.187\times (20-0)$

$=835.48kJ$

Therefore, to melt $2kg$ of ice $835.48kJ$ of heat is required.