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# A-level Question on Moles (easy ) ?

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1. b)Iron Oxide (11.16g of iron reacts to form 15.96g of Iron Oxide)

What is the empirical formula ???

This is all I managed to get to

b) First we work out how many moles of Fe = 11.2/55 = 0.2 moles
Then for Oxygen = 15.96-11.2 = 4.74g/16 = 0.3 moles

So where do I go from here ... ??

any help is greatly appreciated.

kind regards

Sunny
2. Multiply both number of moles by 10 as we want to get them in whole numbers so it will be 2 and 3.
3. Divide by the smallest moles
Fe- 0.2/0.2=1
O- 0.3/0.2=1.5
Times by 2 to get whole number
Fe- 1x2=2
O- 1.5x2=3

Empirical formula = Fe2O3
4. Basically Fe2O3

Iron comes in different forms. It can come in fe(III) or fe(II) so to balance out the charges iron is in its III form.

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