chemical analysis - metal hydroxide precipitates

Question 1

what happens when we add sodium hydroxide to any solutions of calcium ions, magnesium ions, aluminium ions etc?

Answer 1

they all produce a white precipitate

Question 2

what’s the problem with producing a white precipitate?

Answer 2

you can’t distinguish between the tests

Question 3

what happens we add excess sodium hydroxide solution to the aluminium precipitate?

Answer 3

it redissolves

Question 4

how do we work out which white precipitate out of calcium, magnesium and aluminium is the calcium solution?

Answer 4

we will need to do a flame test

Question 5

calcium nitrate + sodium hydroxide ->
Ca(NO3)2 + 2NaOH

Answer 5

sodium nitrate + calcium hydroxide
2NaNO3 + Ca(OH)2

Question 6

magnesium nitrate + sodium hydroxide ->
Mg(NO3)2 + 2NaOH

Answer 6

sodium nitrate + magnesium hydroxide
2NaNO3 + Mg(OH)2

Question 7

aluminium nitrate + sodium hydroxide ->
Al(NO3)2 + 3NaOH

Answer 7

sodium nitrate + aluminium hydroxide
3NaNO3 + Al(OH)3

Question 8

what can we use the hydroxide solutions to test for?

Answer 8

3 other metal ions

Question 9

what do Copper II ions react with sodium hydroxide to form?

Answer 9

a blue precipitate of copper (II) hydroxide

Question 10

what does Iron (II) ions react with sodium hydroxide to form?

Answer 10

a green precipitate of iron (II) hydroxide

Question 11

what does Iron (III) react with sodium hydroxide to form?

Answer 11

a brown precipitate of iron (III) hydroxide