C15

Question 1

What are some methods to prevent rusting?

Answer 1

-coating iron or steel with paint, oil or grease, plastic, a less reactive metal or a more reactive metal
- galvanising

Question 2

How does galvanising work?

Answer 2

Coating iron or steel ion zinc.
The zinc is more reactive, so it reacts before the iron or steel does (sacrificial protection).

Question 3

What are the two types of poly(ethene)?

Answer 3

LD (low density) poly(ethene)
HD (high density) poly(ethene)

Question 4

What is LD poly(ethene) like?

Answer 4

Long, branched strands -> low density

Question 5

What is HD poly(ethene) like?

Answer 5

Packed together strands -> high density

Question 6

How do you change the properties of LD poly(ethene)?

Answer 6

Using very high pressures and a trace of oxygen

Question 7

How do you change the properties of HD poly(ethene)?

Answer 7

Using a catalyst at 50°c and a slightly raised pressure

Question 8

What are the raw materials are used in the Haber Process and where they come from?

Answer 8

Nitrogen from the air
Hydrogen from natural gas

Question 9

How does the haber process work?

Answer 9

Nitrogen and hydrogen are purified. They are passed over an iron catalyst at a high temperature (450°c) and at a high pressure (200 atmospheres)

Question 10

How does pressure change the yield of ammonia?

Answer 10

High pressure=high yield
High pressures need lots of energy+ very expensive
Compromise of 200 atmospheres for a high yield but low cost and low risk of explosion

Question 11

How does temperature change the yield of ammonia?

Answer 11

Low temp=high yield
Low temp is a slow reaction and slows catalyst
Compromise of 450°c for a high yield but a fast reaction.