Question

A sample of air containing SO₂ as an impurity measures 1 kiloliter at STP. It is passed through excess of aqueous solution of H₂O2. The resultant solution required 20 ml of 0.1 N NaOH solution for complete neutralization. If mass of SO2 present is x. Then value of 1000x/8 is ?

Answer 1

CaCO

3

⇌

Δ

CaO+CO

2

Let pure sample of CaCO

3

=x grams

Mass of CaO produced after decomposition =22.4 g

Molar mass of CaCO

3

=100 g/mol

and, Molar mass of CaO=56 g

If 100% is pure, then

100 g CaCO

3

⟶56 g of CaO

Also,y g of CaCO

3

⟶22.4 g of CaO

Dividing these two,

y

100

=

22.4

56

y=40 grams

∴ Percentage of purity =

Totalmassofimpure

Massofpuresample

×100=

50

40

×100=80%