Calculate the empirical formula of each of the following substances with the following compositions. a 3.60 g of magnesium and 10.65 g of chlorine

b 9.1 g of lithium and 10.4 g of oxygen

The empirical formula :

MgCl₂

Li₂O

Given

a 3.60 g of magnesium and 10.65 g of chlorine

b 9.1 g of lithium and 10.4 g of oxygen

Required

The empirical formula

Solution

The empirical formula is the smallest comparison of atoms of compound forming elements.

A molecular formula is a formula that shows the number of atomic elements that make up a compound.

(empirical formula) n = molecular formula

a. mol ratio of Mg (Ar=24 g/mol) and Cl(Ar=35.5 g/mol)

Mg : Cl

=3.6/24 : 10.65/35.5

=0.15 : 0.3 = divide by 0.15

=1 : 2

The empirical formula : MgCl₂

b. a. mol ratio of Li (Ar=7 g/mol) and O(Ar=16 g/mol)

Li : O

=9.1/7 : 10.4/16

=1.3 : 0.65 = divide by 0.65

= 2 : 1

The empirical formula : Li₂O