A `6.90 M` solution of `KOH` contains 30% by weight of `KOH`. Calculate the density of the solution.

Explanation

6.90 M KOH solution means 6.90 moles of KOH are present in 1 litre of the solution.
But 6.90 moles of KOH `=6.90 xx56 g=386.4g`
Thus, volume of solution containing 386.4 g KOH= 1000 mL
`30%` by mass of KOH solution means that 30 g of KOH are present in 100 g of the solution.
`therefore" Mass of solution containing 386.4 g KOH"=(100)/(30)xx386.4g=1288g`
`therefore" Density of solution "=("Mass")/("Volume")=("1288 g")/("1000 mL")="1.288 g mL"^(-1)`