2.6 Reactions of Inorganic Compounds in Aqueous Solution

Question 1

Define a Lewis acid.

Answer 1

Electron pair acceptor

Question 2

Define a Lewis base.

Answer 2

Electron pair donator

Question 3

Write the formula for the 2 aqua metal ions with the charge 2+

Answer 3

(see page 1 in the chemrevise revision guide)

Question 4

Write the formula for the 2 aqua metal ions with the charge 3+

Answer 4

(see page 1 in the chemrevise revision guide)

Question 5

In the formation of a complex ion what is the Lewis base and what is the Lewis acid?

Answer 5

Ligand - Lewis base

Metal ion - Lewis acid

Question 6

Write the general equilibria that happens in aqueous solutions of metal ions.

Answer 6

(see page 1 in the chemrevise revision guide)

Question 7

Why is the acidity of [M(H2O)6]3+ greater than that of [M(H2O06]2+?

Answer 7

It has a greater polarising power (charge/size ratio) of the 3+ metal ion. The greater the polarising power, the more strongly it attracts the water molecule. This weakens the O-H bond so it breaks more easily.

Question 8

How do metal-aqua ions react with limited OH- and limited NH3?

Answer 8

The bases OH- and ammonia when in limited amounts form the same hydroxide precipitates. They form in deprotonation acid base reactions.

Question 9

Write the equation of Cu-aqua ion with a limited amount of OH- ions

Answer 9

(see page 1 in the chemrevise revision guide)

Question 10

Write the equation of Al-aqua ion with a limited amount of OH- ions

Answer 10

(see page 1 in the chemrevise revision guide)

Question 11

Write the 2 equations of Fe-aqua ion with a limited amount of OH- ions

Answer 11

(see page 1 in the chemrevise revision guide)

Question 12

How do Al-aqua ions react with excess OH-?

Answer 12

With excess NaOH the aluminium hydroxide dissolves. Al becomes [Al(OH)4]- (aq) colourless solution.

This hydroxide is classed as amphoteric because it reacts and dissolves in both acids and bases.

Question 13

Write the equation of Al-aqua ions with excess OH-

Answer 13

(see page 1 in the chemrevise revision guide)

Question 14

How do Cu-aqua ions react with excess NH3?

Answer 14

With excess NH3 a ligand substitution reaction occurs with Cu and its precipitate dissolves to form a deep blue solution.

This substitution is incomplete with Cu.

In this reaction NH3 is acting as a Lewis base donating an electron pair.

Question 15

Write the equation of Cu-aqua ions with excess NH3

Answer 15

(see page 1 in the chemrevise revision guide)

Question 16

How do 2+ metal ions react with carbonate solution?

Answer 16

The 2+ ions with carbonate solution results in MCO3 ppt being formed (Cu blue/green, Fe(II) green)

These are precipitation reactions.

Question 17

Write the equation for 2+ Cu ions reacting with carbonate solution.

Answer 17

(see page 2 in the chemrevise revision guide)

Question 18

Write the equation for 2+ Fe ions reacting with carbonate solution.

Answer 18

(see page 2 in the chemrevise revision guide)

Question 19

Write the equation for 2+ Cu-aqua ions reacting with carbonate solution.

Answer 19

(see page 2 in the chemrevise revision guide)

Question 20

Write the equation for 2+ Fe-aqua ions reacting with carbonate solution.

Answer 20

(see page 2 in the chemrevise revision guide)

Question 21

How do 3+ metal ions react with carbonate solution?

Answer 21

The 3+ ions with carbonate solution form a M(OH)3 ppt and CO2 gas is evolved.

Al forms white ppt
Fe(III) forms brown ppt

These are classed as acidity reactions.

Question 22

Write the equation for 3+ Fe-aqua ions reacting with carbonate solution.

Answer 22

(see page 2 in the chemrevise revision guide)

Question 23

Write the equation for 3+ Al-aqua ions reacting with carbonate solution.

Answer 23

(see page 2 in the chemrevise revision guide)

Question 24

Look at 2+ ion summary on page 3 in the chemrevise revision guide

Answer 24

understand?

Question 25

Look at 3+ ion summary on page 3 in the chemrevise revision guide

Answer 25

understand?