Question

Choose the molecular formula of an oxide of iron in which the mass per cent of iron and oxygen are 69.9 and 30.1 respectively and its molecular mass is 160. *
(a) FeO
(b) Fe₃O₄
(c) Fe₂0₃
(d) FeO₂​

Answer 1

Answer:

option c is correct

Explanation:

Fe₂0₃

Answer 2

Given - Mass percent of iron - 69.9

Mass of percent of oxygen - 30.1

Molecular mass of iron oxide - 160

Find - Empirical formula of iron oxide.

Solution - To find empirical formula, using following calculations -

Let the empirical formula be - Fe(a)O(b)

For Fe,

mass percentage of iron*molar mass of iron oxide = atomic mass of iron*a moles of iron.

69.9/100*160 = 56*a

a = 2

For O,

mass percentage of oxygen*molar mass of oxygen oxide = atomic mass of oxygen*b moles of oxygen

30.1/100*160 = 16*b

b = 3.01 = 3

Hence, keeping the values of a and b in assumed empirical formula - Fe2O3. Thus, correct formula of oxide of iron is - (c) Fe₂0₃