Explain what is meant by the term enthalpy change of formation.
Give the equation for the reaction whose enthalpy change is the standard enthalpy change of formation of liquid sulfur trioxide, $\text{SO}_3$. Include state symbols.
Ammonia is made by the Haber process: $\text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightleftharpoons 2\text{NH}_3(\text{g})$. Use bond energies from the Data Booklet to work out the enthalpy change of reaction for the Haber process. Include a sign in your answer.
State the key operating conditions for the Haber process.
Explain the reasons for the temperature and pressure choices in the Haber process.
Write an equation for the formation of diammonium hydrogen phosphate by reaction between ammonia and phosphoric acid, $\text{H}_3\text{PO}_4$.
Explain this reaction using the Br\o nsted-Lowry theory.
Explain how the excessive use of nitrate fertilisers can cause a major fall in water quality in rivers.
Oxides of nitrogen are formed by the action of bacteria on nitrate fertilisers. Explain the problems caused by the release of oxides of nitrogen into the atmosphere. Include an equation in your answer.