Test For Ions

Question 1

how do we test for transition metal ions?

Answer 1

• add aqueous sodium hydroxide

Question 2

how do we test for the Cu2+ ion?

Answer 2

• blue solution reacts with NaOH(aq) to form a blue precipitate of copper(II) hydroxide

Question 3

how do we test for Fe2+ ion?

Answer 3

• pale green solution reacts with NaOH(aq) to forma green precipitate of iron(II) hydroxide

Question 4

what happens when excess NaOH is added to Cu2+?

Answer 4

• the blue ppt is insoluble in excess sodium hydroxide

Question 5

what happens when excess NaOH is added to Fe2+?

Answer 5

• ppt is insoluble in excess sodium hydroxide but turns brown at its surface when in contact with air
• iron(II) is oxidised to iron(III)

Question 6

how do we test for Fe3+ ions?

Answer 6

• pale yellow solution reaction with NaOH(aq) to form an orange brown precipitate of iron(II) hydroxide

Question 7

what happens when excess NaOH is added to Fe3+?

Answer 7

• ppt in insoluble in excess NaOH

Question 8

how do we test for Mn2+ ions?

Answer 8

• pale pink solution reacts with NaOH(aq) to form a light-brown precipitate of manganese(II) hydroxide which darkens on standing in air

Question 9

what happens when excess NaOH is added to Mn2+?

Answer 9

• insoluble in excess sodium hydroxide

Question 10

how do we test for Cr3+ ions?

Answer 10

• violet solution reacts with NaOH(aq) to form a grey green precipitate of chromium(II) hydroxide

Question 11

what happens when excess NaOH is added to Cr3+?

Answer 11

• ppt is soluble in excess sodium hydroxide forming a dark green solution