QUESTION 4 Answer all parts (i) The decomposition of hydrogen peroxide; 2H₂O₂ 2H₂O + O2 (ii) has an activation enthalpy of 72 kJ mol¹ and a standard enthalpy change of - 196 kJ mol. Draw a fully labelled potential energy diagram for the system. Propose a structure for the activated species and calculate the activation enthalpy for the reverse reaction. [8 marks] Experimentally, the decomposition of hydrogen peroxide is observed to be first order with respect to H2O2 and has a rate coefficient (k) of 6.56×10 s at 298 K. Write the rate law for this reaction. For a starting concentration of [H2O2] 0.9 mol dm³, calculate the initial rate of reaction and the rate after 2 minutes at 298 K. Comment on your answers. = [6 marks] (iii) The decomposition of hydrogen peroxide in the presence of bromide ions (Br) has an activation enthalpy is 28 kJ mol'. Assume that the 'A' factor is the same with and without Br and determine the effect on the rate coefficient at 298 K. [6 marks]