Required Practical 7: identifying ions

Question 1

compound “A” produced a lilac flame test
A sample of compound A was reacted with silver nitrate solution and dilute nitric acid
Yellow precipitate was formed
identify compound A

Answer 1

potassium iodide

A lilac flame test tells us that compound a contains the potassium ion. The silver nitrate test produced a yellow precipitate. This tells us that compound contains the iodide ions
Compound A is potassium iodide

Question 2

Compound B produced an orange-red flame test

a sample of compound B effervesced when tested with hydrochloric acid

The gas produced turned lime-water cloudy

identify compound B

Answer 2

calcium carbonate

The orange-red flame test tells us that compound B contains the calcium ion. When compound B was reacted with an acid, it effervesced and the gas turned lime water cloudy this tells us that compound me also contains a carbonate ions so compound B is calcium carbonate

Question 3

Compound C reacts with sodium hydroxide solution and produced a blue precipitate

compound C was then reacted with barium chloride solution and dilute hydrochloric acid

This reaction produced a white precipitate
identify compound C

Answer 3

copper sulphate
The blue precipitate tells us that compounds C must contain the copper ion.
Compound C also produced a white precipitate with barium chloride and hydrochloric acid telling us that compound C contains the sulphate ion
compounds C was copper sulphate