In: Chemistry
If a solution of NaOH has a 20% mass percent of NaOH and a density of 1.22 g/ml, what is the molarity of this solution ?
Answer –
We are given, 20% mass percent of NaOH , density = 1.22 g/mL
So, 20% mass percent of NaOH means 20 g of NaOH in 100 g of solution
So, moles of NaOH = mass of NaOH / molar mass of NaOH
= 20 g / 39.9969 g.mol-1
= 0.500 moles of NaOH
Now we need to convert 100 g od solution to volume
We know,
Density = mass / volume
So, volume = mass / density
= 100 g / 1.22g.mL-1
= 81.97 mL
So, molarity of solution = 0.500 mole / 0.08197 L
= 6.1 M
So, molarity of this solution is 6.1 M