How much pure water must be mixed with 10 liters of a 25% acid solution to reduce it to a 10% acid solution?

May 30, 2017

15 litres of added water

Explanation:

We need to reduce 25% to 10%

Let the amount of acid in the mix be $\frac{x}{100}$

This gives a final acid content of x/100xx25%

The target concentration is 10%

Set x/100xx25%=10%

x=(10%xx100)/(25%)

$x = 40$

Thus $\frac{40}{100}$ of the final blend is the acid
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Let the total volume of the blend be $v$

We have 10 litres of acid so

$\frac{40}{100} v = 10$

$v = \frac{10 \times 100}{40} = \frac{100}{4} = 25$ litres all together

Thus the added water is 25-10=15 litres