Question

A sample of an unknown compound contains 0.21 moles of zinc, 0.14 moles of phosphorus, and 0.56 moles of oxygen. What is the empirical formula?

Answer 1

To determine the empirical formula, we need to find the simplest whole-number ratio of the elements present in the compound.

The mole ratios of zinc (Zn), phosphorus (P), and oxygen (O) in the compound are approximately:

Zn: 0.21 moles
P: 0.14 moles
O: 0.56 moles

To find the simplest whole-number ratio, we can divide the number of moles of each element by the smallest number of moles.

Dividing the moles by 0.14 (the smallest number of moles), we get:

Zn: 0.21 moles / 0.14 moles ≈ 1.5
P: 0.14 moles / 0.14 moles = 1
O: 0.56 moles / 0.14 moles ≈ 4

Rounding these ratios to the nearest whole number, we get:

Zn: 2
P: 1
O: 4

Therefore, the empirical formula of the compound is Zn2P1O4, which can be simplified as Zn2PO4.