Question

Calculate the empirical formula of each of the following substances with the following compositions.

Answer 1

Explanation:

Note: Molar masses of elements can be found online or in the periodic table.

Moles of Magnesium

= 3.60g / (24.3g/mol) = 0.148mol.

Moles of Chlorine

= 10.65g / (35.45g/mol) = 0.300mol.

Mole ratio of Magnesium to Chlorine

= 0.148mol : 0.300mol = 1 : 2.

Hence we have the empirical formula MgCl2.

Moles of Lithium

= 9.1g / (6.94g/mol) = 1.311mol.

Moles of Oxygen

= 10.4g / (16g/mol) = 0.650mol.

Moles ratio of Lithium to Oxygen

= 1.311mol : 0.650mol = 2 : 1.

Hence we have the empirical formula Li2O.