Question

A compound X contains 32% of A, 20% of B and remaining percentage of C. Then, the empirical formula of X is ______.

(Given atomic masses of A = 64; B = 40; C = 32

Options

• AB₂C₂

• ABC₄

• A₂BC₂

• ABC₃

Answer 1

A compound X contains 32% of A, 20% of B and remaining percentage of C. Then, the empirical formula of X is ABC₃.

Explanation:

Given: Percentage of A = 32

Percentage of B = 20

The total percentage of all elements in a compound is 100%.

∴ Percentage of C = 100 − (32 + 20)

= 100 − 50

= 48%

To find the number of moles, divide the percentage (or mass in a 100 g sample) of each element by its respective atomic mass:

Moles of A = `32/64`

= 0.5 mol

Moles of B = `20/40`

= 0.5 mol

Moles of C = `48/32`

= 1.5 mol

Divide each mole value by the smallest number of moles calculated (0.5) to find the simplest whole-number ratio:

Ratio of A = `0.5/0.5`

= 1

Ratio of B = `0.5/0.5`

= 1

Ratio of C = `1.5/0.5`

= 3

Using the simplest whole-number ratio of 1 : 1 : 3 for elements A, B, and C, respectively, the empirical formula is ABC₃.