Acids, Bases and Salts

Question 1

What is the pH scale?

Answer 1

A measure of how acidic or alkaline a solution is

Question 2

What’s the pH of normal rain?

Answer 2

5.6

Question 3

What the pH of acid rain?

Answer 3

Around 4

Question 4

Give an example of an acid that has pH of around 1

Answer 4

1. Car battery acid 2. Acid in stomach

Question 5

Give an example of an acid that has pH of around 3

Answer 5

1. Vingar 2. Lemon juice

Question 6

Give an example of a substance that has a pH around 8-9

Answer 6

Washing-up liquid

Question 7

Give an example of a substance that has a pH around 12

Answer 7

Bleach `

Question 8

Give an example of a substance that has a pH around 13-14

Answer 8

Drain cleaner

Question 9

What are examples of bases?

Answer 9

Metal oxides and hydroxides

Question 10

What are bases?

Answer 10

Substance that will react with acid to form salt

Question 11

What is an alkali?

Answer 11

Base that dissolves in water to from solution

Question 12

What are examples of alkalis?

Answer 12

Soluble hydroxides

Question 13

What’s the word equation for neturalisation?

Answer 13

Acid + Base → Salt + Water

Question 14

What is the balanced symbol equation for neutralisation? (include states)

Answer 14

H⁺_(aq) + OH^-_(aq) → H₂O_(l)

Question 15

What makes solutions acidic?

Answer 15

Hydrogen ions, H⁺_(aq)

Question 16

What makes solutions alkaline?

Answer 16

Hydroxide ions, OH^-_(aq)

Question 17

What’s the symbol for hydrochloric acid?

Answer 17

HCl

Question 18

What’s the symbol nitric acid?

Answer 18

HNO₃

Question 19

What’s the symbol sulfuric acid?

Answer 19

H₂SO₄

Question 20

What’s the symbol for chloride?

Answer 20

Cl₂

Question 21

What’s the symbol for nitrate?

Answer 21

NO₃

Question 22

What’s the symbol for sulfate?

Answer 22

SO₄

Question 23

When ammonia dissolves in water, what is produced?

Answer 23

Alkaline solution (ammonium hydroxide)

Question 24

What is ammonium hydroxide used for?

Answer 24

Used to produce ammonium salts

Question 25

When calcium hydroxide in water (limewater) reacts with carbon dioxide, what is produced?

Answer 25

Calcium carbonate

Question 26

How can souble salts be made?

Answer 26

By reacting acids with metals, insouble bases or alkalis

Question 27

Why are not all metals suitable for making souble salts?

Answer 27

Some too reactive and others not enough

Question 28

What can be used to show when an acid and alkali have completely reacted to produce salt solution?

Answer 28

Indicator

Question 29

Give an example of an insoluble base and acid that can be reacted together to give a souble salt (name souble salt made)

Answer 29

Make copper chloride using hydrochloric acid and copper oxide

Question 30

Explain how you would make copper chloride

Answer 30

1. Warm dilute acid using Bunsen burner & then turn it off
2. Add insoluble base to acid a bit at a time until no more reacts (i.e. until base in excess). Know when acid has been naturalised: after stirring = excess solids sinks to bottom of flask.
3. Filter excess solid to get salt solution
4. (Cystallisation) Heat solution in water bath or electric heater to evaporate some of water
5. Then stop heating it and leave solution to cool
6. Crystals of salt should form = can be filtered out of solution and then dried

Question 31

How can solid salts be produced from salt solutions?

Answer 31

Via crystallisation

Question 32

What is precipitation used for?

Answer 32

Used to remove unwanted ions from solutions

Question 33

Give an example of when precipitation is used in real life

Answer 33

E.g. treating water for drinking or in treating effluent

Question 34

What is a precipitate?

Answer 34

When an insoluble salt (solid) is formed from combing 2 solutions containing soluble salts

Question 35

Describe the method for a precipitation

Answer 35

1. Sodium iodide (solution 1) + silver nitrate (solution 2) (undergo a double displacement reaction)
2. To isolate iodide (precipitate), filter it with funnel lined with filter paper (conical flask with catch excess sodium nitrate)
3. Since it’s insoluble, can rinse contents with distilled water to ensure that you get all of precipitate produced

Question 36

What is distilled water?

Answer 36

Water with ion impurities removed

Question 37

What is residue?

Answer 37

Solid that stays behind in the filter paper

Question 38

What is a filtrate?

Answer 38

Liquid that passes through filter paper

Question 39

What does acids do in aqueous solutions?

Answer 39

Ionise it (produce hydrogen ions, H⁺)

Question 40

What do strong acids do in water?

Answer 40

Ionise completely in water

Question 41

What do strong acids do in water, in terms of particles?

Answer 41

All acid particles dissociate to release H⁺ ions

Question 42

What do weak acids do in water?

Answer 42

Don’t fully ionise in solution

Question 43

What do weak acids do in water, in terms of particles?

Answer 43

Only small proportion of acid particles dissociate to release H⁺ ions

Question 44

What type of reaction is the ionisation of weak acids in water?

Answer 44

A reversible reaction

Question 45

What do reactions of acids involve when reacting with other substances?

Answer 45

H⁺ ions

Question 46

Why are strong acids more reactive than weak acids of same concentration?

Answer 46

Concentration of H⁺ ions is higher = rate of reaction is faster

Question 47

What does the strength of an acid tell you?

Answer 47

What proportion of acid molecules ionise in water

Question 48

What does the concentration of an acid measure?

Answer 48

Measures how much acid there’s in a certain volume of water i.e. how watered down an acid is