Question

The molarity and molality of 40% NaOH solution(by mass) respectively are(If density of solution is 1.2gm/ml..)

Answer 1

40g of NaOH is present in 100g of solution
Moles of NaOH = 40/40 = 1 mol

Volume of solution = Mass / Density
= 100 / 1.2
= 83.3 L

Molarity = moles of NaOH / Volume of solution
= 1 / 83.3
= 0.012 M

Molality = (Moles of NaOH / Wieght of solvent in grams) * 1000
= (1 / 90) * 1000
= 11.1 m