3.2.6 - Reactions of metal ions in aqueous solutions

Question 1

All transition metal compounds such as copper sulfate form what in water?

Answer 1

[X(H2O)6]x+

This is known as a octahedral hexa-aqua ion

Question 2

Colours of metals and their reaction products (except Cl- reaction)

Answer 2

Iron 2+ = Green
Iron 3+ = Brown
Copper = Blue
Aluminium = White

Question 3

What happens when the 3+ ions react with Na2CO3?

Answer 3

Solution + bubbles given off

Question 4

Which metal salt reacts with excess NaOH? Describe the reaction.

Answer 4

[Al(H2O)3(OH)3] + OH- ——> [Al(H2O)2(OH)4]- + H2O

Question 5

Which metal salt reacts with excess NH3? Describe the reaction

Answer 5

[Cu(H2O)4(OH)2] + 4NH3 ——> [Cu(H2O)2(NH3)4]2+ + 2H2O + 2OH-

Question 6

Why are complexes formed from transitions metals coloured?

Answer 6

• Absorption of some wavelengths of light
• Causes promotion of electrons in d-orbitals
• Remaining wavelengths are reflected

Question 7

What is the equation to work out the energy absorbed by each electron?

Answer 7

E = hc/λ

h = Planck’s constant
c = speed of light
λ = Wavelength of light absorbed (m)

Question 8

What happens when a 2+ metal aqua ion reacts with Na2CO3?

Answer 8

Water is freed up, metal binds to CO3

Question 9

What is the equation for the reaction of Fe(H2O)6 (3)+ and Na2CO3?

Answer 9

2Fe(H2O)6 + 3CO3(2-) —-> 2[Fe(H2O)3(OH)3] + 3CO2 + 3H2O

Question 10

What are the three things you can use to identify metal ions?

Answer 10

• Na2CO3
• NaOH
• NH3

Question 11

What does Al(H20)6 form when reacting with Na2CO3?

Answer 11

[Al(H20)3(OH)3]