State one natural and one man-made occurrence of oxides of nitrogen.

1. (a)State one natural and one man-made occurrence of oxides of nitrogen.[1]
2. (b)(i)Balance the equation above for the formation of N₂O and N₂O₃ from NO.[1]
3. (b)(ii)State how the oxidation number of nitrogen changes during this reaction. NO → N₂O from to NO → N2O3 from to[1]
4. (b)(iii)Calculate the entropy change for the reaction at 298 K. Include the units in your answer. ΔS° = units =[2]
5. (b)(iv)State whether the sign of ΔS° calculated in (iii) agrees with that predicted from your balanced equation in (i). Explain your answer.[1]
6. (c)(i)Write the expression for Kp for this equilibrium. Include the units in your answer. Kp = units =[1]
7. (c)(ii)A 1.00 dm³ flask at 25 °C is filled with pure N2O3(g) at an initial pressure of 0.60 atm. At equilibrium, the partial pressure of NO2(g) is 0.48 atm. Calculate the partial pressures of NO(g) and N2O3(g) at equilibrium. Hence calculate the value of Kp at 25 °C. p(NO(g)) = p(N2O3(g)) = Kp =[2]
8. (d)(i)Deduce the order of reaction with respect to each reactant. Explain your reasoning. order with respect to [NO(g)] order with respect to [O2(g)][2]
9. (d)(ii)State the rate equation for this reaction. Use the rate equation to calculate the rate constant. Include the units for the rate constant in your answer. rate = rate constant, k = units of k =[3]
10. (e)(i)State what is meant by the term co-ordination number.[1]
11. (e)(ii)Describe how the co-ordination number of the iron changes during this reaction. from to[1]
12. (e)(iii)Only one stereoisomer of Fe(CO)2(NO)2 exists. Use this information to suggest the geometry of the complex.[1]
13. (f)(i)Complete the three-dimensional diagrams to show the three isomers of Ru(NO)L2Cl3.[2]
14. (f)(ii)Suggest the type of isomerism shown.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.