A sample of caustic soda cotains 74.6 na₂o (by weight) . find the purity of sample.

100 Kg of cautic soda flaker
Given-
Cautic soda flaker contain 74.6 Kg of Na₂O

Now,
2 NaOH = Na₂O + H₂O
2 moles of NaOH = 1 mole of of Na₂O
.
Thus,
Amount of NaOH in 62 Kg of Na₂O = 80 Kg of NaOH
Amount of NaOH in 74.6 Kg of Na₂O = (80 x 74.6)/62 = 96.26 Kg

% purity of the flakes
= (Obtained mass / total mass) x 100
= (92.26 Kg /100 Kg) x 100
= 96.26 %