C4- Chemical Changes- Paper 1

Question 1

What 3 ways can metals be separated from their oxides?

Answer 1

1. Reduction using carbon
2. Electrolysis
3. Their already pure and don’t need to be seperated

Question 2

What is reduction using carbon?

Answer 2

Chemically extracting oxygen by reacting the metal with carbon so that the oxygen bonds to the carbon. This only works when the metal is less reactive than carbon

Question 3

Write a balanced equation for the reduction of lead oxide, PbO, by carbon, C.

Answer 3

2PbO + C > 2Pb + CO2

Question 4

A mining company tried to extract calcium from its ore by reduction with carbon. The process didn’t work. Explain why. [1 mark]

Answer 4

Calcium is more reactive than carbon, so calcium oxide won’t be reduced by carbon.

Question 5

What is the general equation for reduction by carbon?

Answer 5

Metal oxide + carbon > metal + carbon dioxide/ monoxide

Question 6

How are precious metals like gold and silver found in rocks?

Answer 6

Pure- as they are so unreactive they don’t react with anything.

Question 7

Why can’t carbon be used to extract potassium?

Answer 7

Potassium is more reactive than carbon, so carbon can’t displace it.