How much water must be evaporated from 60 kilograms of a 15 salt solution in order to obtain a 40% solution?

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Answer 1 · 2017-12-30T12:57:37

28.5 kg

The initial strength of the solution is 15% m/m. [Mass/Mass]

That means, the salt present in the solution is = $60 * 15/100$ kg = $9$ kg

The water present = $60 - 9$ kg = $51$ kg

If we evaporate some of the water off the solution, the salt should not change its mass, unless it decomposes or something like that.

Let's assume that we have evaporated $x$ kg of water.

According to the condition,

$(9)/(51-x)*100 = 40$

$rArr (900)/(51-x) = 40$

$rArr 51 - x = 900/40$

$rArr 51 - x = 22.5$

$rArr x = 28.5$

That means 28.5 kg of water needs to be evaporated.