How much heat energy is released when 5.0 g of water at 20oC changes into ice at 0oC? Take specific heat capacity of water = 4.2 J g−1 K−1, specific latent heat of fusion of ice = 336 J g−1.
Heat released when 5 g water at 20°C turns to 5 g water at 0°C is,
H1 = (5)(4.2)((20 – 0)
=> H1 = 420 J
Heat released when 5 g of water at 0°C turns to 5 g of ice at 0°C.
H2 = (5)(336) = 1680 J
So, total heat released is = H1 + H2 = 2100 J