4. Chemical changes

Question 1

What method is used to extract metals that are more reactive than Carbon?

Answer 1

Electrolysis

Question 2

What method is used to extract metals that are more reactive than hydrogen, but less reactive than carbon?

Answer 2

Reduction with carbon

Question 3

Define acid in terms of pH

Answer 3

A substance with a pH of less than 7

Question 4

What does (aq) stand for?

Answer 4

Aqueous: when something is dissolved in water

Question 5

State the three common acids and give their formulae

Answer 5

Hydrochloric acid, HCl(aq), Sulphuric acid, H?SO?(aq), Nitric acid, HNO?

Question 6

How do you measure pH?

Answer 6

With an indicator or pH probe.

Question 7

What is a base?

Answer 7

A metal oxide, hydroxide or carbonate that will react with an acid. E.g. copper oxide

Question 8

What is an alkali?

Answer 8

A soluble base. E.g. sodium hydroxide

Question 9

Which ions are always present in a solution of an alkali?

Answer 9

OH?

Question 10

What type of salts are formed by the three main acids?

Answer 10

Hydrochloric acid produces chlorides, sulphuric acid = sulphates, nitric acid = nitrates

Question 11

Which ions always react together in a neutralization reactions between acids and alkalis?

Answer 11

H? and OH?

Question 12

metal + acid ?

Answer 12

? salt + hydrogen gas

Question 13

metal hydroxide + acid ?

Answer 13

? salt + water

Question 14

metal oxide + acid ?

Answer 14

? salt + water

Question 15

metal carbonate + acid ?

Answer 15

? salt + water + carbon dioxide

Question 16

What is electrolysis?

Answer 16

Using electricity to break down a substance

Question 17

Do positive ions move to the anode or the cathode?

Answer 17

Cathode

Question 18

Do negative ions move to the anode or the cathode?

Answer 18

Anode

Question 19

In the electrolysis of solutions, what is produced at the cathode?

Answer 19

Hydrogen, unless the metal ion present is less reactive

Question 20

In the electrolysis of solutions, what is produced at the anode?

Answer 20

Oxygen, unless the other negative ion present is a halide ion

Question 21

What is oxidation?

Answer 21

Oxidation is the loss of electrons

Question 22

What is reduction?

Answer 22

Reduction is the gain of electrons

Question 23

What is a strong acid?

Answer 23

An acid which completely splits up into its ions in water. Eg. HCl

Question 24

What is a weak acid?

Answer 24

An acid which will have some molecules which do not split up into their ions. Eg. Ethanoic acid

Question 25

What is a concentrated acid?

Answer 25

An acid where there are lots of acid particles in the water.