C3.3 Types Of Chemical Reactions

Question 1

What is reduction?

Answer 1

• Loss of oxygen from a substance

- Gain of electrons

Question 2

What is oxidation?

Answer 2

• Gain of oxygen by a substance

- Loss of electrons

Question 3

What is an acid?

Answer 3

A substance that releases hydrogen ions when it dissolves in water to make an aqueous solution

Question 4

What is an alkali?

Answer 4

A substance that releases hydroxide ions when it dissolves in water to make an aqueous solution

Question 5

What can you use to measure pH of a solution?

Answer 5

• pH meter

- Universal indicator

Question 6

What is a base?

Answer 6

• A substance, usually a metal oxide or metal hydroxide, that can neutralise acids
• If it dissolves in water, it is also an alkali

Question 7

Give the general equation for neutralisation

Answer 7

acid + base —> salt + water

Question 8

Give general equation for when acids react with carbonates

Answer 8

acid + carbonate —> salt + water + carbon dioxide

Question 9

Give general equation for when acids react with metals

Answer 9

acid + metal —> salt + hydrogen

Question 10

State the difference between a dilute and concentrated acid

Answer 10

• Dilute acid contains a low ratio of acid to volume of solution
• Concentrated acid contains a high ratio of acid to volume of solution

Question 11

State the difference between a strong and weak acid

Answer 11

• Weak acids are partially ionised (only a small fraction of their molecules release H+ ions)
• Strong acids are fully ionised (all of their molecules release H+ ions)

Question 12

State relationship between concentration of acid and pH of solution

Answer 12

• As concentration increases by a factor of 10

- pH of solution decreases by 1