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Question
How much heat energy is released when 5 g of water at 20° C changes to ice at 0° C?
[Specific heat capacity of water = 4.2 J g-1 ° C-1 Specific latent heat of fusion of ice = 336 J g-1]
Solution
θ = mc Δ θ + mL
= 5 × 4.2 × 20 + 5 × 336
= 420 + 1680
= 2100 joule
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