Question

A sample of a pure compound contains 2.04g of sodium, 2.65 X 1022 atoms of carbons and 0.132 mol of oxygen atoms. Find he empirical formula.

Answer 1

Moles of Na in sample = Given mass/Molar mass of Na
= 2.04 g/23 g mol-1
​ = 0. 088
Mole of carbon
1 mole C = 6. 022 x 1023 atoms of C
​Therefore , 2.65 x 1022 atoms = 2.65 ​x 1022 / 6. 022 x 1023
= 0. 044
Moles of oxygen = 0.132
Molar ratio of Na , C and O = 0.088 : 0.044 : 0.132
The simple whole number ration = 2 : 1 : 3
Empirical formula of compound = Na2CO3