Ammonia

In the Haber process for the manufacture of ammonia, which of the following statements are correct?

I) The catalyst used is a transition metal.

II) Unreacted nitrogen and hydrogen are circulated back into the system.

III) Both reactants are obtained from the fractional distillation of liquefied air.

IV) The reaction is never complete and yield achieved is only about

10 – 15%

• I, II and III

• I, II and IV

• II, III and IV

• All of the above

Which statement is not correct about the Haber process?

• High pressure of 250 atm is used to increase yield.

• Each hydrogen molecule reacts with three nitrogen molecules to form two molecules of ammonia.

• A low temperature of 450 ^oC is used.

• The reaction is reversible.

Nitrogen and hydrogen reacts to form ammonia in the Haber process.

Which statement is correct?

• A high yield of ammonia is favoured by high pressure.

• A high yield of ammonia is favoured by high temperature.

• A high yield of ammonia is favoured by adding catalyst.

• The reaction between nitrogen and hydrogen is irreversible.

The diagram shows the manufacture of ammonia using hydrogen and nitrogen in the presence of catalyst.

What are the processes P and Q and catalyst Y?

• P: cracking ; Q: fractional distillation ; Y: iron

• P: cracking ; Q: fractional distillation ; Y: nickel

• P: fractional distillation ; Q: cracking ; Y: iron

• P: combustion ; Q: cracking ; Y: nickel

Arsine, AsH₃, is a gas that behaves like ammonia.

Which ions would be produced when arsine dissolves in water?

• AsH⁺ and H⁺

• AsH₃⁺ and OH⁻

• AsH₄⁺ and H⁺

• AsH₄⁺ and OH⁻

Some farmers use fertiliser containing ammonium nitrate and calcium carbonate.

Why is this fertilizer useful?

• It provides all the essential nutrients for plant growth.

• They form a compound which is not washed away by rain water.

• It provides nitrogen and carbon dioxide which are required for plant growth.

• It provides nitrogen for plant growth and calcium carbonate to neutralise the excess acidity of the soil.

A high yield of ammonia is favoured in the Haber process by conditions of high pressure and low temperature. However, in practice a high temperature is employed because at low temperature,

• ammonia decomposes back to its original reactant.

• the activation energy is too low.

• the catalyst is inactive.

• the reaction is too slow.

Industrial ammonia is obtained by the Haber process.

Which of the following is an incorrect statement about the process?

• The hydrogen needed is obtained mainly by cracking of petroleum oil.

• The reaction is endothermic and therefore a moderate temperature of 450^oC is used.

• High pressure favours the production of ammonia.

• The industrial catalyst used is iron.

During the Haber Process, ammonia that is produced is separated from the reaction mixture by

• passing the gaseous mixture through fused calcium chloride.

• dissolving the other two gases.

• filtering out the other two gases by passing through cotton wool.

• cooling the mixture.

One of the essential conditions for the Haber process is a temperature of 450 ^oC.

Predict what will happen to the ammonia yield when the temperature is increased to 550 ^oC. Explain your answer. [2 marks]