A 62% by mass of an aqueous solution of acid has specific gravity 1.8. This solution is diluted such that the specific gravity of solutin became 1.2. Find the % by wt of acid in new solutiuon.

Explanation

density = `"mass"/"volume"`
`1.8=100/("volume of "sol^(n)) rArr "volume of solution" =100/1.8`
Let x gm water is added in solution
then `d="mass"/"volume"`
`1.2=(100+x)/(100/1.8+x)`
`1.2 times 100/1.8 times 1.2x=100+x`
`200/3+1.2x=100+x`
`0.2x=100-200/3=100/3`
`x=100/(3 times 0.2)=1000/6=500/3=166.67`
mass of new solution = 100 + 166.67 = 266.67
266.67 gm solution contains 62 gm of acid
% by mass `=62/266.67 times 100=23.24%`