C4f

Question 1

What is thermal decomposition?

Answer 1

-when a substance breaks down into at least two other substances when heated

Question 2

What happens when you heat a transition metal carbonate?

Answer 2

• break down into metal oxide and carbon dioxide

- this usually results in a colour change

Question 3

What are precipitations?

Answer 3

-when a solid forms in a solution

Question 4

What is a precipitation reaction?

Answer 4

-where two solution react and an insoluble solid form in the solution

Question 5

What happens if you react soluble transition metal compounds with sodium hydroxide?

Answer 5

• you get insoluble hydroxide

- which the precipitates out

Question 6

How can you use precipitations to test for transition metal ions?

Answer 6

• some insoluble transition metal hydroxides have different colours
• you can use this fact to test which transition metal ions a solution contains
• e.g. adding sodium hydroxide to an unknown soluble salt may result in an orange/brown precipitation, you know you have got iron(III) hydroxide and so have Fe3+ ions in he solution

Question 7

Name some transition metal hydroxides and their colours.

Answer 7

• copper(II) hydroxide=blue solid
• iron(II) hydroxide=green/grey solid
• iron(III) hydroxide=orange/brown solid