Precipitation Reactions

Question 1

Cu2+ with NaoH
soluble or insoluble in excess?
ammonia added?

Answer 1

Cu(OH)2 blue solution to blue precipitate
insoluble
ligand substitution

Question 2

Fe2+ with NaoH
soluble or insoluble in excess?
ammonia added?

Answer 2

Fe(OH)2 pale green solution to green precipitate, oxidised in air to Fe(OH)3 orange-brown precipitate
insoluble
Same as with NaOH- no further reaction, doesn’t dissolve

Question 3

Fe3+ with NaoH
soluble or insoluble in excess?
ammonia added?

Answer 3

Fe(OH)3 pale yellow solution to orange-brown precipitate
insoluble
Same as with NaOH- no further reaction, doesn’t dissolve

Question 4

Mn2+ with NaoH
soluble or insoluble in excess?
ammonia added?

Answer 4

Mn(OH)2 pale pink solution to light brown precipitate, darkens in air
insoluble
Same as with NaOH- no further reaction, doesn’t dissolve

Question 5

Cr3+ with NaoH
soluble or insoluble in excess?
ammonia added?

Answer 5

Cr(OH)3 violet solution to green-grey precipitate
soluble, [Cr(OH)6]3- dark green solution
ligand substitution