Explain the meaning of 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: $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$. Use bond energies from the Data Booklet to calculate the enthalpy change of reaction for the Haber process. Your answer should include a sign.
State the essential operating conditions used in 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 the reaction between ammonia and phosphoric acid, $\text{H}_3\text{PO}_4$.
Explain this reaction using the Brønsted-Lowry theory.
Explain how the uncontrolled use of nitrate fertilisers can cause a serious decline in water quality in rivers.
Oxides of nitrogen are made by bacteria acting on nitrate fertilisers. Explain the problems caused by oxides of nitrogen being released into the atmosphere. Include an equation in your answer.