Empirical formula - Higher tier

You can use information about reacting masses to calculate the formula of a compound. Here is an example:

Question

• Suppose 3.2 g of sulfur reacts with oxygen to produce 6.4 g of sulfur oxide. What is the formula of the oxide?
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• Use the fact that the A_r of sulfur is 32 and the A_r of oxygen is 16

Here is the calculation again in tabular form to help you remember the steps:

Steps to calculation the formula of a compound

Step	Action	S	O
1	Find masses	3.2	3.2
2	Look up given Ar values	32	16
3	Divide masses by Ar	0.1	0.2
4	Find the ratior	1	2

Result: the formula for the oxide = SO₂