Question

Calculate molarity and morality of 40% of NaOH(w/w). The density of solution is 1.2 g/ml

Answer 1

Firstly, 40% NaOH implies 40 g NaOH in 100g solution.

Thus, mass of NaOH = 40g

No. of moles = Given mass / Molar mass = 40/40 = 1 mol

Now, assuming solvent to be water since it isn't specified, density of water = 1g/mL

Also, mass of solution = 100g

Thus density = mass / volume

Which implies, 1 = 100 / volume

Therefore, Volume = 100mL

Now, molarity = no. of moles / volume in L

Molarity = 1 x 1000 / 100

Molarity = 10M