Question 159478
In words:
(ml of acid in 86% solution)/(ml of 86% solution + added water) = 40%
Let {{{h}}}= the ml of water to be added
The ml of sulphuric acid in 50 ml of 86% solution is:
{{{.86*50 = 43}}}ml
{{{43 / (50 + h) = .4}}}
Multiply both sides by {{{50 + h}}}
{{{43 = .4*(50 + h)}}}
{{{43 = 20 + .4h}}}
{{{.4h = 23}}}
{{{h = 57.5}}}ml
57.5 ml of water must be added to get a 40% solution
check:
{{{43 / (50 + h) = .4}}}
{{{43 / (50 + 57.5) = .4}}}
{{{43 / 107.5 = .4}}}
{{{.4 = .4}}}
OK