Topic 4 - Acids and bases

Question 1

What is the pH scale an indication of?

Answer 1

the hydrogen ion concentration and runs from below 0 to above 14

Question 2

A neutral solution has

Answer 2

equal concentrations of H+(aq) and OHˉ(aq) ions

Question 3

Water is neutral because

Answer 3

it dissociates according to the equation
H2O(l) ⇌ H+(aq) + OH−(aq) producing equal concentrations of hydrogen and hydroxide ions.

Question 4

At any time, only a few
water molecules are

Answer 4

dissociated into free ions

Question 5

What does ⇌ mean?

Answer 5

that a reaction is reversible and occurs in both directions

Question 6

Acidic solutions have

Answer 6

a higher concentration of H+(aq) ions than OHˉ(aq) and have a pH
below 7.

Question 7

Alkaline solutions have

Answer 7

a higher concentration of OHˉ(aq) ions than H+(aq) ions and have a pH above 7.

Question 8

Dilution of an acidic solution with water will

Answer 8

decrease the concentration of H+(aq) and the pH will increase towards 7

Question 9

Dilution of an alkaline solution with water will

Answer 9

decrease the concentration of OHˉ(aq) and the pH will decrease towards 7

Question 10

What do soluble non-metal oxides form when they dissolve in water

Answer 10

acidic solutions

Question 11

What do soluble metal oxides form when they dissolve in water?

Answer 11

alkaline solutions

Question 12

metal oxide + water

Answer 12

metal hydroxide

Question 13

Bases

Answer 13

neutralise acids

Question 14

What compounds are bases?

Answer 14

metal oxides, metal hydroxides, metal carbonates and ammonia

Question 15

Bases that dissolve in water

Answer 15

form alkaline solutions

Question 16

What is a neutralisation reaction?

Answer 16

when a base reacts with an acid to form water. A salt is also formed in this reaction.

Question 17

metal oxide + acid
(neutralisation)

Answer 17

= salt + water

Question 18

metal hydroxide + acid
(neutralisation)

Answer 18

= salt + water

Question 19

metal carbonate + water (neutralisation)

Answer 19

= salt + water + carbon diocxide

Question 20

What does the name of the salt from neutralisation depend on?

Answer 20

the acid and base used

Question 21

What do hydrochloric acid, sulfuric acid, and nitric acid produce when they react with bases?

Answer 21

Hydrochloric acid produces chlorides
Sulfuric acid produces sulfates
Nitric acid produces nitrates

Question 22

What are spectator ions?

Answer 22

ions that remain unchanged by the reaction

Question 23

How can spectator ions be identified?

Answer 23

by using reaction equations

Question 24

What is the neutralisation reaction equation (without spectator ions) for metal oxides?

Answer 24

2H⁺(aq) + O²⁻(s) → H₂O(ℓ)

Question 25

What is the neutralisation reaction equation (without spectator ions) for metal hydroxides?

Answer 25

H⁺(aq) + OH⁻(aq) → H₂O(ℓ)

Question 26

What is the neutralisation reaction equation (without spectator ions) for aqueous metal carbonates?

Answer 26

2H⁺(aq) + CO₃²⁻(aq) → H₂O(ℓ) + CO₂(g)

Question 27

What is the neutralisation reaction equation (without spectator ions) for soluble metal carbonates?

Answer 27

2H⁺(aq) + CO₃²⁻(s) → H₂O(ℓ) + CO₂(g)

Question 28

In an acid-base titration, what is the concentration of the acid/base determined by?

Answer 28

accurately measuring the volumes used in the neutralisation reaction

Question 29

What is an indicator used for in an acid/base titration?

Answer 29

to show the end-point of the reaction

Question 30

Given a balanced equation for the reaction occurring in any titration (concentration)

Answer 30

the concentration of one reactant can be calculated given the concentration of the other reactant and the volumes of both solutions

Question 31

Given a balanced equation for the reaction occurring in any titration (volume)

Answer 31

the volume of one reactant can be calculated given the volume of the other reactant and the concentrations of both solutions

Question 32

What can neutralisation reactions be used to prepare?

Answer 32

soluble salts

Question 33

How can titration be used to produce a soluble salt?

Answer 33

by noting the volumes of acid and alkali, then repeating the reaction without the indicator to produce an uncontaminated salt solution. The solution can then be evaporated to dryness.

Question 34

What happens after titration to produce a soluble salt?

Answer 34

the reaction is repeated without the indicator, and the resulting salt solution is evaporated to dryness.

Question 35

What is the process for producing soluble salts from insoluble metal carbonates or oxides?

Answer 35

excess base is added to the acid, the mixture is filtered, and the filtrate is evaporated to dryness.