(1) One way to purify saltwater is to allow it to vaporize from the salt solutio
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Question
(1) One way to purify saltwater is to allow it to vaporize from the salt solution and condense on a cool plastic receptor surface, where it can be collected for consumption (the principle being that salt is not carried with the water vapour). Even in a water-air mixture, the latent heat of vaporization is still needed to convert liquid water to vapour, i.e., energy is required for the air and saltwater to reach thermal equilibrium. At 20°C, how much heat energy (in kJ) is required to purify 300 litres of saltwater?Explanation / Answer
at 20 C, energy required for water to vapourise = L
L = (2500.8 - 2.36T + 0.0016T^2 - 0.00006T^3) J / g
T = 20 C
hence
L = 2453.76 J/g
given mass of water = m
volume of saltwater, V = 300 liters
taking density of water = 1 kg/lit
m = 300 kg = 300,000 g
hence
energy required = 2453.76*300,000 J = 736.128 MJ
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