C2.5

Question 1

Name an alkali:

Answer 1

Sodium hydroxide.

Question 2

What is a base?

Answer 2

Substances that can neutralise acids.

Question 3

What ions do all acids form when we add them to water?

Answer 3

Hydrochloric acid.

Question 4

What does the state symbol (aq) stand for?

Answer 4

Shows that the ions are in an aqueous solution (Dissolved in water).

Question 5

What ions do all alkalis form when we add them to water?

Answer 5

Hydroxide ions.

Question 6

What does the state symbol (s) stand for?

Answer 6

Solution.

Question 7

What do we use to show how acidic or alkaline a solution is?

Answer 7

pH scale.

Question 8

What does e reaction between an acid and a metal produce?

Answer 8

Salts.

Question 9

What does the state symbol (g) stand for?

Answer 9

Gas.

Question 10

What is formed when an acid plus a base react?

Answer 10

Salt and water are formed.

Question 11

Name the salt formed when dilute sulphuric acid reacts with zinc oxide:

Answer 11

Sulfates.

Question 12

What does the state symbol (l) stand for?

Answer 12

Liquid.

Question 13

What salt is used as a fertiliser to provide crops with nitrogen?

Answer 13

Ammonium nitrate.

Question 14

Name two other important ways of making salts from solutions:

Answer 14

• react an acid and alkali together to form a soluble salt

- reacting solutions of two soluble salts together

Question 15

What is a precipitate?

Answer 15

Insoluble solid formed.

Question 16

What is electrolysis?

Answer 16

Means splitting up using electricity.

Question 17

What do we call the substance broken down by electrolysis?

Answer 17

The electrolyte.

Question 18

What happens during electrolysis?

Answer 18

Positively charged ions move to the negative electrode and at the same time the negative ions move to the positive electrode.

Question 19

Which electrode do positive ions move to?

Answer 19

Negative electrode.

Question 20

Which electrode do negative ions move to?

Answer 20

Positive electrode.

Question 21

How do negative charged ions become neutral atoms in electrolysis?

Answer 21

They lose electrons.

Question 22

How do positively charged ions become neutral atoms in electrolysis?

Answer 22

They gain electrons.

Question 23

What is oxidation?

Answer 23

Losing electrons.

Question 24

What is reduction?

Answer 24

Gaining electrons.

Question 25

Why is aluminium used to make overhead power cables?

Answer 25

They have a low density but are very strong.

Question 26

Why must aluminium oxide be molten for electrolysis to take place?

Answer 26

Enables the ions to move to the electrodes.

Question 27

Are the oxide ions reduced or oxidised in the electrolysis of molten aluminium oxide? Why?

Answer 27

Oxidised because it loses 2 electrons.

Question 28

What are the 3 products made when we electrolyse brine?

Answer 28

• chlorine gas is produced at the positive electrode
• hydrogen gas is produced at the negative electrode
• sodium hydroxide solution is also formed

Question 29

What is chlorine used for?

Answer 29

To make a solution of bleach.

Question 30

What is hydrogen used for?

Answer 30

Make sit very useful in ex food industry.

eg margarine

Question 31

What is sodium hydroxide used for?

Answer 31

Used to make soap and paper.

Also bleach.

Question 32

Name four metals that we can use to electroplate another metal:

Answer 32

• steel
• gold
• silver
• chromium

Question 33

Why do we electroplate objects?

Answer 33

• to protect the metal beneath from corroding
• to make the object look more attractive
• to increase the hardness of a surface and its resistance to scratching
• to save money

Question 34

Where are the nickel atoms oxidised?

Answer 34

In a solution.

Question 35

What is formed when nickel atoms are oxidised?

Answer 35

Form nickel ions.