4.7.3 Acids and Alkalis

Question 1

What is made when a metal reacts with an acid?

Answer 1

A salt and hydrogen

Question 2

How do we test for hydrogen gas?

Answer 2

Put a lit splint into it - it makes a squeaky pop

Question 3

What is made when an acid reacts with an alkali or base?

Answer 3

A salt and water

Question 4

What gas is produced when a carbonate reacts with an acid?

Answer 4

Carbon dioxide

Question 5

How do we test for carbon dioxide gas?

Answer 5

Use limewater - it turns cloudy when carbon dioxide is present

Question 6

What is a neutralisation reaction?

Answer 6

An acid and alkali react together to form neutral substances

Question 7

What is the difference between an alkali and a base?

Answer 7

An alkali will dissolve in water (is soluble) but a base is insoluble.

Question 8

What is the name of the salt made when magnesium and hydrochloric acid react together?

Answer 8

Magnesium Chloride

Question 9

What is the name of the salt made when magnesium reacts with nitric acid?

Answer 9

Magnesium nitrate

Question 10

What is the name of the salt made when magnesium reacts with sulphuric acid?

Answer 10

Magnesium Sulphate

Question 11

How do you collect an INSOLUBLE SALT?

Answer 11

FILTER it from the mixture.

Question 12

How do you collect a SOLUBLE salt?

Answer 12

EVAPORATE off the water to collect the CRYSTALS

Question 13

What is an exothermic reaction?

Answer 13

A reaction that releases heat energy- and heats up the reaction mixture.

Question 14

What is an endothermic reaction?

Answer 14

A reaction that absorbs heat energy - and cools down the reaction mixture.

Question 15

What ion is present in all acids?

Answer 15

H+

Question 16

What ion in present in all alkalis?

Answer 16

OH-

Question 17

What happens when you add universal indicator to an acid?

Answer 17

It turns red/orange/yellow

Question 18

What happens when you add universal indicator to an alkali?

Answer 18

It turns blue/purple

Question 19

What happens when you add universal indicator to a neutral substance?

Answer 19

It goes green

Question 20

What pH are acids?

Answer 20

1-6

Question 21

What pH is a neutral solution?

Answer 21

7

Question 22

What pH is an alkali?

Answer 22

8-14

Question 23

What is the general equation for neutralisation?

Answer 23

H+ + OH- -> H20

Question 24

HIGHER TIER ONLY:

What do we mean by a strong acid?

Answer 24

An acid that fully dissociates (breaks down) in solution - releasing H+ ions.

Question 25

HIGHER TIER ONLY:

What do we mean by a weak acid?

Answer 25

An acid that only partially dissociates (break down) in solution.

Question 26

HIGHER TIER ONLY:

What are examples of strong acids?

Answer 26

Nitric acid, sulphuric acid, hydrochloric acid

Question 27

HIGHER TIER ONLY:

What are examples of weak acids?

Answer 27

Citric acid (In fruit), Ethanoic acid (in vinegar), carbonic acid (in fizzy drinks)

Question 28

HIGHER TIER ONLY:

What is the link between concentration of an acid and pH?

Answer 28

The HIGHER the concentration of H+ ions in an acid, the lower the pH is.