Compound Y is a pale green, crystalline solid. It contains iron(II) ions (Fe2+\text{Fe}^{2+}Fe2+), sulfate ions (SO42−\text{SO}_4^{2-}SO42−) and water of crystallisation.
A student dissolved some of compound Y in water and then added aqueous sodium hydroxide solution. She obtained a green precipitate.
Give the formula of the green precipitate formed in the reaction.
Another student tested a solution of compound Y for sulfate ions using dilute hydrochloric acid, followed by a few drops of barium chloride solution. She obtained a white precipitate.
Why is the dilute hydrochloric acid necessary in this test?
The empirical formula of compound Y is FeSO11H14\text{FeSO}_{11}\text{H}_{14}FeSO11H14.
Write the formula of compound Y to show its water of crystallisation.
Outline how you would carry out a flame test on a solid sample.
