(a) C3H6 reacts with HBr(g) in an addition reaction. (i) Define addition reaction. (ii) Complete Fig. 3.1 to show the mechanism for the addition reaction between C3H6 and HBr to produce 2-bromopropane. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. [Figure 3.1] (iii) Explain why the major product of this reaction is 2-bromopropane rather than 1-bromopropane. (b) H2(g) and nickel are added to alkene X. Fig. 3.2 shows how the concentration of X changes with time. [Figure 3.2] (i) Use Fig. 3.2 to identify the limiting reagent in this reaction. Explain your answer. (ii) Use Fig. 3.2 to describe how the gradient changes as the reaction proceeds. State what this shows about the rate during this reaction. (c) Hydrocarbon Y contains two C=C groups. There are no other functional groups present. Y reacts with an excess of H2(g) to produce hexane, C6H14. [Table 3.1] Use Table 3.1 to calculate the enthalpy change per mole of C6H14 produced in this reaction. (d) Hydrocarbon Y reacts with H2(g). Fig. 3.3 shows the distribution of energies of H2(g) at temperature T. Area A represents the number of molecules with energy greater than or equal to the activation energy, EA, at temperature T. [Figure 3.3] (i) Annotate Fig. 3.3 to show the effect of adding nickel to Y and H2(g) at temperature T. (ii) Area B (not labelled on Fig. 3.3) represents the number of molecules with energy greater than or equal to the activation energy when nickel is added at temperature T. State the difference, if any, between areas A and B. Explain the significance of your answer on the rate of hydrogenation of Y. Give your answer in terms of collisions. (e) Alkene Z contains two C=C bonds. Z reacts with an excess of hot concentrated acidified KMnO4 to produce only CH3COCH3, HOOCCH2COOH, CO2 and H2O. Suggest the structure of Z.