industrial processes (topic 10)

Question 1

state the name of the industrial process used to manufacture ammonia

Answer 1

haber process

Question 2

explain the purpose of the iron catalyst (2)

Answer 2

• increases the rate of reaction
• without changing the percentage yield of ammonia

Question 3

explain why a temperature of 450°C is used in the haber process (3)

Answer 3

• increases the rate of reaction
• but lowers percentage yield
• 450°C is a compromise between speed, cost and yield

Question 4

Answer 4

increase the pressure of the reaction

Question 5

Answer 5

the amounts of nitrogen, hydrogen and ammonia become constant

Question 6

explain what effect a pressure lower than 200 atmospheres would have on: the rate of attainment of equilibrium, the yield of ammonia (3)

Answer 6

• it would take longer to reach equilibrium
• equilibrium yield decreases
• equilibrium shifts to the left

Question 7

the production of ammonia is an exothermic reaction, explain the effect of increasing the temperature on the percentage yield of ammonia (2)

Answer 7

• reduces percentage yield
• high temperature favours the reverse reaction

Question 8

state the name of the catalyst used in the Haber process

Answer 8

iron catalyst

Question 9

what happens to the rate of the forward and backward reactions at dynamic equilibrium

Answer 9

rate of forward reaction is equal to the rate of backward reaction

Question 10

state what happens to the position of the dynamic equilibrium and the yield of ammonia when the pressure is increased, explain why this shift occurs (4)

Answer 10

• dynamic equilibrium shifts to the right or shifts in favour of ammonia production
• percentage yield of ammonia increases
• equilibrium shifts to side with fewer molecules in order to oppose the increase in pressure
• equilibrium shifts to right as fewer molecules

Question 11

explain why ammonia can be extracted when the gases pass through a condenser (1)

Answer 11

ammonia has a higher boiling point than nitrogen and hydrogen

Question 12

draw a dot and cross diagram to represent a molecule of NH3

Answer 12

Question 13

write a word equation for the reaction between calcium phosphate and nitric acid

Answer 13

calcium phosphate + nitric acid → calcium nitrate + phosphoric acid

Question 14

fertilisers can be compared using their NPK value, one fertiliser has an NPK value of 12:11:13, explain why this information is useful to farmers (2)

Answer 14

• because NPK value shows the ratio of nitrogen, potassium, and phosphorus
• different ratios are suited to different crops
• farmers can choose fertilisers with required properties

Question 15

state the temperature and pressure used in the Haber process

Answer 15

• temperature = 450°C
• pressure = 200 atm

Question 16

describe how increasing the temperature would affect the percentage yield of ammonia (2)

Answer 16

• increasing the temperature would decrease the percentage yield of ammonia
• the production of ammonia is exothermic
• high temperatures favour the endothermic (reverse) reaction