Haber Process & NPK Fertilisers Practice Questions

The nitrogen used in the Haber process is obtained from the air.

Give one source of the hydrogen used in the Haber process.

The purified gases are passed over a catalyst.

Name the catalyst used in the Haber process.

Which conditions of temperature and pressure are used in the Haber process?

Tick ($\checkmark$) one box.

Explain what the symbol $\rightleftharpoons$ in the equation shows about the reaction.

NPK fertilisers contain compounds of three elements needed for healthy plant growth.

Name the three elements.

Which salt in the table contains two of the three elements needed in an NPK fertiliser?

A gardener wants to mix two of the salts in the table to make a fertiliser that supplies all three NPK elements.

Name the two salts the gardener should use.

Name one potassium compound that is obtained by mining and used in fertilisers.

Phosphate rock is also obtained by mining, but it cannot be used directly as a fertiliser.

Explain why.

Name one substance that phosphate rock is treated with so that it can be used as a fertiliser.

The mixture leaving the reactor is cooled to about $-50$ °C in the condenser.

Use Table 1 to explain why only the ammonia is removed as a liquid.

Explain why the unreacted nitrogen and hydrogen are recycled.

Only a small percentage of the nitrogen and hydrogen is converted to ammonia each time the gases pass through the reactor.

Give the reason why.

Use the equation to explain why increasing the pressure increases the yield of ammonia at equilibrium.

A yield of over 40 % of ammonia could be obtained at a pressure of 400 atmospheres, but most plants use about 200 atmospheres.

Suggest two reasons why a pressure of about 200 atmospheres is used.

Name the salt made when ammonia solution reacts with nitric acid.

Ammonia solution also reacts with sulfuric acid to make ammonium sulfate.

Write a balanced symbol equation for this reaction.

Nitric acid made from ammonia is used to treat phosphate rock, which contains calcium phosphate.

Name the two products formed when calcium phosphate reacts with nitric acid.

In the Haber process, purified nitrogen and hydrogen are passed over an iron catalyst at about 450 °C and about 200 atmospheres.

$$\mathrm{N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)} \qquad \text{the forward reaction is exothermic}$$

Explain why these conditions are used in industry.

In your answer you should refer to the rate of reaction, the position of equilibrium and cost.

Write a balanced symbol equation for the reaction of ammonia with nitric acid to make ammonium nitrate.

In the industrial method, no indicator is used and the solid collected does not need to be purified.

Explain why the solid does not need to be purified.

Evaluate the two methods for producing a large mass of ammonium nitrate for sale to farmers.