What is the purity of conc. sulphuric acid solution(specific gravity=1.8 gm/ml), if 5 ml of this solution is neutralised by 84.6 ml of 2 N NaOH?

 

i have solved it till density or weight of acid in 1ml =1.678 g/ml

my book says purity=1.678/1.8*100 = 92.12%

I am unable to get that purity point. How is purity related to specific gravity.If possible explain the concept of specific gravity. I know that specific gravity of solution = weight of solution/ volume of the solution. Please clarify my concept in context to the above definition of spec gravity. 

neways, here's the solution::

 

using the normality equivalence, the normality of H₂SO₄ = 33.84 N

 

=> 1L of solution has 33.84 gram eq. of H₂SO₄

 

=>1L of solution has 33.84 * 98/2 = 1658.16g of H₂SO₄

 

=> density should be 1.658 g/ml but it's given the density is 1.8g/ml

 

=> % purity is 1.658/1.8 * 100 = 92.11%

 

there might be some calculation error....