Inorganic Tests for Ions

Question 1

Mg2+ + 2OH- > Mg(OH)2

Answer 1

White PPT, does not redissolve in excess NaOH

Question 2

Al3+ + 3OH- > Al(OH)3

Answer 2

White PPT, redissolves in excess NaOH to form [Al(OH)4]- ion (colourless)

Question 3

Fe2+ + 2OH- > Fe(OH)2

Answer 3

Pale green > mossy green PPT, does not redissolve in excess NaOH

Question 4

Fe3+ + 3OH- > Fe(OH)3

Answer 4

Orange brown > orange brown PPT, does not disappear in excess NaOH

Question 5

Cu2+ + 2OH- > Cu(OH)2

Answer 5

Blue > pale blue PPT, does not redissolve in excess NaOH

Question 6

2CU2+ +4I- > 2CuI + I2

Answer 6

Beige/pale brown PPT

Question 7

Zn2+ + 2OH- > Zn(OH)2

Answer 7

Colourless > white PPT, redissolves in excess NaOH to form [Zn(OH)4]2-

Question 8

Pb2+ +2OH- > Pb(OH)2

Answer 8

Colourless > white PPT, redissolves in excess NaOH. Pb(OH)2 + 2OH- > [Pb(OH)4]2- colourless solution

Question 9

Pb2+ + 2I- > PbI2

Answer 9

Bright yellow PPT

Question 10

Ba2+ + SO42- > BaSO4

Answer 10

White PPT