Set 16 Chemistry [Paper] 1

SECTION A: (46 MARKS) Answer all questions from this section. 1. (a) Complete the following equations for nuclear reactions. (i) …………………… (01 mark) (ii) ……… (01 marks) (b) When a radioactive isotope was left to stand, it decayed by 12.5% of its original value in 45 days. Calculate the half-life of the radioactive isotope. (2½ marks) ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… 2. (a) State three factors that can affect electron affinity. (1½ marks) ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… (b) Write equation for the first electron affinity of sulphur. (01 mark) …………………………………………………………………………………… (c) The first and second electron affinities of sulphur are and respectively. Explain the difference in the electron affinities of sulphur. (04 marks) ………………………………………………………………………………………………………………………………………………………………...……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… 3. Polystyrene is formed by polymerization of phenylethene. (a) (i) Write the structural formula of polystyrene. (01 mark) ………………………………………………………………………………………………………………………………………………………………..……….. (ii) Name the type of polymerization involved in the formation of polystyrene. (½ mark) ……………………………………………………………………………… (b) The osmotic pressure of a solution containing 5.5g of polystyrene in 1 dm3 of benzene is 1.0 x atmospheres at 200C. (i) Calculate the relative molecular mass of polystyrene.(R = 0.082 atm dm3 ) (02 marks) ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… (ii) Determine the number of monomers that formed the polystyrene. (1½ marks) ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………… 4. (a) The figure below shows the energy diagram for the reaction between nitrogen monoxide and oxygen. Identify K and L. K…………………………………………… (½ mark) L…………………………………………… (½ mark) State whether the reaction is endothermic or exothermic. (½ mark) …………………………………………………………………………..……….. Give a reason for your answer in (a) (ii). (½ mark) …………………………………………………………………………………… (b) The experimental results in the table below were obtained for the reaction in (a). Deduce the order of the reaction with respect to; nitrogen monoxide. (01 mark) ………………………………………………………………………………………………………………………………………………………………………… Oxygen. (01 mark) ……………………………………………………………………………………………………………………………………………………………….………... Write the rate equation for the reaction. (01 mark) ………………………………………………………………………………………………………………………………………………………………………… (c) Calculate the (i) rate constant (k) for the reaction and state its units. (1½ …