2021 Paper 2

Question 1

Describe considerations needed for pressure and temperature when producing ammonia

Answer 1

Higher temperature gives a higher rate of reaction because of more frequent collisions. However it would give a lower yield as the reaction is exothermic. It would also use more energy for a high temperature. Higher pressure also gives a higher rate of reaction because of more frequent collision. It would give a higher yield as there are more molecules in the left hand side. Higher pressure require stronger vessel so costs increase as well as energy. Therefore, the chosen temperature is a compromise between rate and yield as well as rate and cost. Chosen pressure is a compromise between rate and cost as well as yeild and cost

Question 2

Why does the rate of reactions graph go horizontal

Answer 2

Because the reaction has stopped as the reactant is used up

Question 3

Describe how copper is extracted from low grade ores by phytomining

Answer 3

Grow plants on land containing copper ores. Burn plants to produce ash. Dissolve the ash in acid and electrolyse it

Question 4

Why is phytominng for copper not as widely used

Answer 4

Land not available
Phytomining takes a long time

Question 5

Test for an alkene

Answer 5

Bromine water:
Brown / orange in alkane
Colourless in alkene

Question 6

Name the soluble salt produced when calcium phosphate reacts with nitric acid

Answer 6

Calcium nitrate

Question 7

Name the soluble salt produced when calcium phosphate reacts with phosphoric acid

Answer 7

Triple superphosphate

Question 8

Why is industrial processes better than laboratory processes

Answer 8

Industrial is on a larger scale, quicker and continuous