Reactions of Acids

Question 1

What are acids?

Answer 1

Compounds that release H⁺ ions when dissolved in water.

Question 2

What are alkalis?

Answer 2

Compounds that release OH⁻ ions when dissolved in water.

Question 3

What pH is considered acidic?

Answer 3

Less than 7

Question 4

What pH is considered alkaline?

Answer 4

Over 7

Question 5

What pH is considered neutral?

Answer 5

7

Question 6

What does the pH scale show?

Answer 6

The amount of H⁺ ions in the solution. The more H⁺ ions -> the more acidic/lower the pH.

Question 7

What is an increase of 1 on the pH scale equal to?

Answer 7

A decrease of 10x the number of H⁺ ions in the solution

Question 8

Name 2 indicators.

Answer 8

1. Universal indicator
2. Electronic pH probes

Question 9

What is a strong acid?

Answer 9

Acids that become fully ionised in solution - every molecule splits up into ions

Question 10

What is a weak acid?

Answer 10

Acids that become partially ionised in solution - only a percentage of their molecules split up into ions

Question 11

What does concentration tell us?

Answer 11

How much of a substance is dissolved in water

Question 12

What will a concentrated strong acid look like in water?

Answer 12

Lots of acid ions, completely ionised

Question 13

What will a dilute strong acid look like in water?

Answer 13

Few acid ions, completely ionised

Question 14

What will a dilute weak acid look like in water?

Answer 14

Few acid ions, partially ionised.

Question 15

What will a concentrated weak acid look like in water?

Answer 15

Lots of acid ions, partially ionised

Question 16

What is a salt?

Answer 16

A compound where the hydrogen feom an acid is replaced by a metal

Question 17

When are salts formed?

Answer 17

When acids react with metals or metal compounds

Question 18

What are the main 3 acids?

Answer 18

Sulfuric, nitric, hydrochloric

Question 19

What type of salt is formed in reactions between metals and hydrochloric acid?

Answer 19

Metal chloride

Question 20

What type of salt is formed in reactions between metals and sulfuric acid?

Answer 20

Metal sulfate

Question 21

What type of salt is formed in reactions between metals and nitric acid?

Answer 21

Metal nitrate

Question 22

What ions are formed in reactions between metals and hydrochloric acid?

Answer 22

H⁺, Cl⁻

Question 23

What ions are formed in reactions between metals and sulfuric acid?

Answer 23

2H⁺, SO₄²⁻

Question 24

What ions are formed in reactions between metals and nitric acid?

Answer 24

H⁺, NO₃⁻

Question 25

What forms when acids react with metals?

Answer 25

Salts and hydrogen gas

Question 26

What forms when acids react with metal hydroxides?

Answer 26

Salts and water

Question 27

What forms when acids react with metal oxides?

Answer 27

Salts and water

Question 28

What forms when acids react with metal carbonates?

Answer 28

A salt, water and carbon dioxide

Question 29

What sort of reaction is the one between acids and metals?

Answer 29

A redox reaction
The metal is oxidised
The hydrogen is reduced

Question 30

What are bases?

Answer 30

Substances that neutralise acids to form water in neutralisation reactions.

Question 31

What are metal hydroxides that dissolve in water to form alkaline solutions?

Answer 31

Alkalis

Question 32

What are metal oxides/metal hydroxides that do not dissolve in water?

Answer 32

Bases, but not alkalis

Question 33

What is the process of crystallisation?

Answer 33

1. Acid and base chosen.
2. Put some dilute acid into flask. Heat gently with Bunsen burner.
3. Add small amount of base and stir.
4. Keep adding base until no more reacts - excess
5. Filter to remove excess base
6. Add remaining solution to evaporating dish
7. Use a water bath or electric heater to evaporate water -> salt crystals left behind

Question 34

What does crystallisation produce?

Answer 34

A solid salt

Question 35

When an acid reacts with a metal, what is oxidised?

Answer 35

Metal

Question 36

When an acid is reduced, what is reduced?

Answer 36

Hydrogen