Transition metals

Question 1

Fe 2+ in aqueous solution

Answer 1

[Fe(H2O)6]2+ green solution

Question 2

Cu 2+ in aqueous solution

Answer 2

[Cu(H2O)6]2+ blue solution

Question 3

Fe 3+ in aqueous solution

Answer 3

[Fe(H2O)6]3+. pale violet solution but appears orange due to hydrolysis to some [Fe(H2O)5(OH)]2+

Question 4

Al 3+ in aqueous solution

Answer 4

[Al(H2O)6]3+ colourless solution

Question 5

Add aqueous NaOH dropwise to Fe2+

Answer 5

[Fe(H2O)4(OH)2] green precipitate (darkens on standing due to oxidation to [Fe(H2O)3(OH)3]

Question 6

Add aqueous NaOH dropwise to Cu 2+

Answer 6

[Cu(H2O)4(OH)2] blue precipitate

Question 7

Add aqueous NaOH dropwise to Fe3+

Answer 7

[Fe(H2O)3(OH)3] brown precipitate

Question 8

Add aqueous NaOH dropwise to Al3+

Answer 8

[Al(H2O)3(OH)3] white precipitate

Question 9

addition of excess aqueous NaOH to Fe2+

Answer 9

no further reaction form when was added dropwise

Question 10

addition of excess aqueous NaOH to Cu2+

Answer 10

no further reaction form when was added dropwise

Question 11

addition of excess aqueous NaOH to Fe3+

Answer 11

no further reaction form when was added dropwise

Question 12

addition of excess aqueous NaOH to Al3+

Answer 12

[Al(H2O)2(OH)4]- re-dissolved to give colourless solution

Question 13

adding aqueous NH3 dropwise to Fe2+

Answer 13

[Fe(H2O)4(OH)2] green precipitate which darkens on standing due to oxidation causing [Fe(H2O)3(OH)3]

Question 14

adding aqueous NH3 dropwise to Cu2+

Answer 14

[Cu(H2O)4(OH)2] blue precipitate

Question 15

adding aqueous NH3 dropwise to Fe3+

Answer 15

[Fe(H2O)3(OH)3] brown precipitate

Question 16

adding aqueous NH3 dropwise to Al3+

Answer 16

[Al(H2O)3(OH)3] white precipitate

Question 17

Adding excess aqueous NH3 to Fe2+

Answer 17

no further reaction form when it was added dropwise

Question 18

Adding excess aqueous NH3 to Cu2+

Answer 18

[Cu(H2O)2(NH3)4]2+ deep blue solution

Question 19

Adding excess aqueous NH3 to Fe3+

Answer 19

no further reaction form when it was added dropwise

Question 20

Adding excess aqueous NH3 to Al3+

Answer 20

no further reaction form when it was added dropwise

Question 21

adding aqueous Na2CO3 to Fe2+

Answer 21

FeCO3 green precipitate

Question 22

adding aqueous Na2CO3 to Cu2+

Answer 22

CuCO3 blue-green precipitate

Question 23

adding aqueous Na2CO3 to Fe3+

Answer 23

[Fe(H2O)3(OH)3] brown precipitate and bubbles of CO2 gas

Question 24

adding aqueous Na2CO3 to Al3+

Answer 24

[Al(H2O)3(OH)3] white precipitate and bubbles of CO2 gas

Question 25

adding concentrated HCl to Fe2+

Answer 25

[FeCl4]2- yellow solution

Question 26

adding concentrated HCl to Cu2+

Answer 26

[CuCl4]2-green solution

Question 27

adding concentrated HCl to Fe3+

Answer 27

[FeCl4]-yellow solution

Question 28

adding concentrated HCl to Al3+

Answer 28

[AlCl4]- colourless solution

Question 29

reaction between iodide ions and S2O8 2- catalysed by Fe

Answer 29

S2O8 2- + 2e- –> 2 SO4 2-

Fe3+ + e- –> Fe2+

I2 + 2e- –> 2 I-

all arrows are reversible
reactions can occur either way round which is why Fe2+ or Fe3+ can be the catalyst

overall:
2 I- + S2O8 2- –> I2 + 2 SO4 2-

Question 30

contact process

Answer 30

-catalysed by V2O5

V2O5 + SO2 –> V2O4 + SO3

V2O4 = 0.5O2 –> V2O5

overall:
2 SO2 + O2 –> 2 SO3

Question 31

colours of vanadium ions oxidation state = +5

Answer 31

VO2 + yellow

Question 32

colours of vanadium ions oxidation state = +4

Answer 32

VO 2+ blue

Question 33

colours of vanadium ions oxidation state = 3+

Answer 33

V 3+ green

Question 34

colours of vanadium ions oxidation state = 2+

Answer 34

V 2+ violet

Question 35

haber process

Answer 35

3 H2 + N2 –> 2 NH3

reversible reaction arrow

Question 36

reaction of ethanedioate ions and manganate ions

Answer 36

2 MnO4- + 16H+ + 5C2O42- –> 2 Mn2+ + 8 H20 + 10 CO2

catalysed by Mn2+ ions

Question 37

reaction of manganate ions and iron ions

Answer 37

MnO4- + 8 H+ + 5 Fe 2+ –> Mn2+ + 4 H2O + 5 Fe 3+