Chemistry - C2

Question 1

Which theory is now widely accepted?

Answer 1

• the plate tectonic theory

Question 2

What does evidence need to be for a theory to be accepted?

Answer 2

• repeatable

- agreed

Question 3

What processes are rock recycled by?

Answer 3

• geological processes

Question 4

What are rocks used as?

Answer 4

• building materials

Question 5

Concrete isn’t very strong but what can it be reinforced with to make stronger?

Answer 5

• steel

Question 6

What are metals extracted from?

Answer 6

• rocks

Question 7

What do alloys contain?

Answer 7

• at least one metal but have different properties

Question 8

What is copper extracted and purified by?

Answer 8

• extracted by reduction

- purified by electrolysis

Question 9

What does iron rust in contact with?

Answer 9

• oxygen and water

Question 10

What speeds up rusting?

Answer 10

• salt

Question 11

What is aluminium and what are its characteristics?

Answer 11

• aluminium is a metal with a low density, which does not corrode because it has a protective oxide layer

Question 12

Is the haber process a reversible or irreversible reaction and what does it make?

Answer 12

• reversible

- ammonia

Question 13

What is ammonia used to make?

Answer 13

• nitrogen fertilisers

Question 14

What is the neutralisation equation?

Answer 14

• acid + base –> salt + water

Question 15

What can fertilisers cause?

Answer 15

• eutrophication

Question 16

What do acids react with to make salt?

Answer 16

• metal oxides and hydroxides, and also metal carbonates

Question 17

What is sodium chloride?

Answer 17

• it is an important raw material, obtained by mining it from the ground or by solution mining

Question 18

What is electrolysis used to do?

Answer 18

• it is used to split sodium chloride solution into hydrogen, chlorine and sodium hydroxide

Question 19

In electrolysis, where do they positive and negative ions go?

Answer 19

• the positive ions move to the cathode and the negative ions to the anode

Question 20

What do plate movements cause?

Answer 20

• earthquakes

- volcanoes

Question 21

What is thermal decomposition?

Answer 21

• it is a reaction where one substance breaks down on heating to give at least two new substances

Question 22

What is reinforced concrete?

Answer 22

• it is a composite material which has steel rods or meshes running through it. Composites contain at least two materials that can still be distinguished

Question 23

What are some advantages of recycling copper?

Answer 23

• it has a fairly low melting point so the energy cost to melt is low
• it reduced the need for mining, saving reserves and the environmental problems caused by mining
• it keeps the cost of copper down

Question 24

What are some disadvantages and problems of recycling copper?

Answer 24

• the small amounts used in electrical equipment are difficult to separate
• valuable ‘pure’ copper scrap must not be mixed with less pure scrap, such as solder
• less copper is mined so there are fewer mining jobs
• the actual separating process may produce pollution
• a lot of copper is thrown away as it is difficult to persuade people to recycle it