Question

Latent heat of ether at $0^o$C is $90$cal per g. How much ether should be evaporated to freeze $60$g of water at $0^o$C.

Answer 1

Latent heat of ether = $90cal/g$

Latent heat of water = $80cal/g$

Let required mass of ether be $m$.

$\because$ Heat loss by water = Heat gain by ether

$\Rightarrow 60\times 80=m\times 90$

$\Rightarrow m=53.33g$

So, $53.33g$ of ether should be evaporated to freeze $60g$ of water at $0^{o}C$.