Class 11 Chemistry NCERT Solutions

Question 1.3

Determine the empirical formula of an oxide of iron which has 69.9% iron and 30.1% dioxygen by mass.

Answer:

% of iron by mass = 69.9 % [Given]

% of oxygen by mass = 30.1 % [Given]

Relative moles of iron in iron oxide:

Relative moles of oxygen in iron oxide:

Simplest molar ratio of iron to oxygen:

= 1.25 : 1.88

≈ 1 : 1.5

= 2 : 3

∴ The empirical formula of the iron oxide is Fe₂O_3.