17.5.2 Amphoteric Metal Hydroxides

Question 1

Which statement about an amphoteric substance is not correct?

Answer 1

Amphoteric substances are formed exclusively from deprotonation events.

Question 2

Let’s examine two related metal hydroxide reactions.

Pb(OH)2(s) + 2H+(aq) Pb2+(aq) + H2O(l)

Pb(OH)2(s) + OH-(aq) Pb(OH)3^-(aq)

Which statement about these reactions is not correct?

Answer 2

The forward component of the first reaction is a deprotonation reaction.

Question 3

HCl, an acid, is added to Pb(OH)2 (in water).

Pb(OH)2(s) + 2H+(aq) Pb2+(aq) + H2O(l)

NaOH is added (as a base) to Pb(OH)2 (in water).

Pb(OH)2(s) + OH-(aq) Pb(Oh)3^-(aq)

Which statement about these reactions is not correct?

Answer 3

H2O was the amphoteric substance for these reactions.

Question 4

Look at the two simultaneous reactions.

(Reaction 1)

Mg(OH)2(s) Mg2+(aq) + 2OH-(aq)

where Ksp = 1.2 × 10−11

(Reaction 2)

Zn(OH)2(s) Zn^2+(aq) + 2OH-(aq)

where Ksp = 4.5 × 10−17
We started with a solution that had Zn2+ and Mg2+ ions. Which statement about this event is not correct?

Answer 4

Zn(OH)2(s) dissociates more than Mg(OH)2(s).

Question 5

Amphoteric compounds are _________________

Answer 5

compounds that can act as either bases or acids.

Question 6

Look at the following reactions.

HCO3^-(aq) + OH-(aq) H2O(l) + CO3^2-(aq)

HCO3^-(aq) + H+(aq) H2CO(aq)

What is the amphoteric compound in these reactions?

Answer 6

HCO3−

Question 7

Look at the reactions below.

HCO3^-(aq) + OH-(aq) H2O(l) + CO3^2-(aq)

HCO3^-(aq) + H+(aq) H2CO(aq)

Which statement about these reactions is not correct?

Answer 7

The amphoteric compound in this reaction has a neutral charge.

Question 8

Look at the two metal hydroxide reactions.

Pb(OH)2(s) + 2H+(aq) Pb2+(aq) + H2O(l)

Pb(OH)2(s) + OH-(aq) Pb(OH)3^-(aq)

Which statement about these reactions is not correct?

Answer 8

Pb(OH)3− is the amphoteric compound in the reactions.

Question 9

If we look at two beakers that both have Pb(OH)2 in solution. They are basically Pb(OH)2 solid sitting in the bottom of a beaker that has water as a solvent. Which statement about this initial condition of the solution is not correct?

Answer 9

At equilibrium, the Pb(OH)2 solid will eventually dissolve in the water.

Question 10

HCl, an acid, is added to Pb(OH)2 (in water).

Pb(OH)2(s) + 2H+(aq) Pb2+(aq) + H2O(l)

Which statement about this reaction is not correct?

Answer 10

Equilibrium shifted from right to left as the solution became clear.