Question

How many litres of water must be evaporated away from a 8% strength salt solution to produce 25L of a 20% strength salt solution? Round your final answer to 2 decimal places if necessary.

Answer 1

ANSWER

The volume of water to be evaporated is 37.50L

EXPLANATION:

Given information

The volume of the solution = (25 + x)L

The percentage strength of the solution = 8

The concentration of the solution when water is removed = 20%

Let the volume of water evaporated be x

The next step is to find the value of x

$\begin{gathered} 25(20)\text{ = 8\lparen25 + x\rparen} \\ open\text{ the parentheses} \\ 500\text{ = 200 + 8x} \\ subtract\text{ 200 from both sides of the equation} \\ 500\text{ - 200 = 200 - 200 + 8x} \\ 300\text{ = 8x} \\ Divide\text{ both sides by 8} \\ \frac{300}{8}\text{ = }\frac{8x}{8} \\ x\text{ = 37.50 L} \end{gathered}$

Hence, the volume of water to be evaporated is 37.50L