Topic 5

Question 1

What happens when concentration of reactant is increased?

Answer 1

Increases rate of forward reaction, equilibrium moves to the right

Question 2

What happens when concentration of product is increased?

Answer 2

Increases the rate of the reverse reaction. Equilibrium moves to the left

Question 3

What happens when temperature is increased?

Answer 3

Favours endothermic reaction. Equilibrium moves in direction of endothermic reaction

Question 4

What happens when pressure is increased?

Answer 4

Favours a decrease in pressure. Equilibrium moves to side with fewest moles of gas.

Question 5

What happens when a catalyst is used?

Answer 5

No effect

Question 6

What is equilibrium constant equation?

Answer 6

K = [C]c X [D]d/[A]a X [B]b

Question 7

An acid is a proton …

Answer 7

Donor

Question 8

A base is a proton …

Answer 8

Acceptor

Question 9

What is a conjugate base

Answer 9

Acid - H+

Question 10

What is a conjugate acid?

Answer 10

Base + H+

Question 11

What do strong acids do in aqueous solutions

Answer 11

They completely dissociate into ions

Question 12

What do weak acids do in aqueous solutions?

Answer 12

They only partially dissociate into ions

Question 13

Why is an acidic salt?

Answer 13

The OH ions are removed from the equilibrium, forming molecules of the weak base. The water equilibrium moves to the RHS to replace the OH ions, producing an excess of H, therefore ph < 7

Question 14

Why is an alkaline salt

Answer 14

The H ions of the salt are removed from the equilibrium, forming molecules of weak acid. The water equilibrium moves to the RHS to replace the H ions, producing an excess of OH, therefore pH > 7

Question 15

What is Kw equation?

Answer 15

[H3O+][OH-]

Question 16

What is Kw at 25oC

Answer 16

1.01 X 10-14

Question 17

What are the concentrations of H3O and OH at 25oC?

Answer 17

1.005 X 10-7

Question 18

What happens when an acid is added to an acidic buffer?

Answer 18

When the acid is added the H ions react with the CHCOO ions to produce molecules of the weak acid. As long as there is a large supply of CHCOO ions from the salt the ph remains unchanged

Question 19

What happens when an alkali is added to an acidic buffer?

Answer 19

When the alkali is added the OH ions react with the H ions and form water. The acid equilibrium moves to the right to replace the H ions. The ph remains unchanged

Question 20

What happens when an acid is added to a basic buffer?

Answer 20

When the acid is added the H ions react with the OH ions and form water. The alkali equilibrium moves to the right, and the alkali molecules dissociate to replace the OH ions. The pH is maintained

Question 21

What happens when an alkali is added to a basic buffer?

Answer 21

When the alkali is added, the OH ions react with the NH4 ions to produce molecules of the weak alkali. As long as there is a large supply of NH4 ions from the salt, the pH remains unchanged

Question 22

Strong acid - strong alkali titration rapid change?

Answer 22

Between 4 - 10

Question 23

Strong acid - weak alkali titration rapid change?

Answer 23

Between 3 - 7

Question 24

Weak acid - strong alkali titration rapid change?

Answer 24

Between 8 - 11

Question 25

Weak acid - weak alkali titration rapid change

Answer 25

No rapid change, no possible indicator