Set 9 Chemistry [Paper] 2

1 SECTION A (60 Marks) Answer only three questions from this section . 1.(a) State Le Chaterlier’s Principle. (02 marks) b) Hydrogen iodide decomposes according to the following equation. 2HI(g) H2(g) + I2(g) (i) State the condition for the reaction. (0½ mark) (ii) Describe how the equilibrium constant, for the reaction can be determined by titrimetric method. (08 marks) c) Explain what would happen to the equilibrium posi tion if : (i) Catalyst is added. (02 marks) (ii) Some little potassium solution was added to the mixture. (02½ m arks) d) 102.4 g of hydrogen iodide was heated to equilibrium in 5000 cm3 vessel. If 44.8 g of the hydrogen iodide remained at equilibrium, calculate the value of equilibrium constant, 𝐾𝑐. (05 marks) 2. Discuss the reactions of a) Methyl benzene with chlorine . b) Ethanol with sulphuric acid. c) Chloro ethane with potassium hydroxide. You answer should include: (i) Equations for each reactions. (ii) Acceptable mechanisms for each reactions. (20 m arks) 3. Explain each of the following statements. a) Glucose, 𝐶6𝐻12𝑂6 is much more soluble in water than in benzene. (03 marks) b) Silicon dioxide is a covalent compound but has a very high melting point. (03 marks) c) An aqueous solution of 0 .020 M sucrose has the same freezing point depression as 0.010 M potassium chloride. (04 marks) 2 d) Calcium oxalate is insoluble in water but readily dissolves in dilute nitric acid. (05 marks) e) Silicon tetrachloride fumes in most air but carbon tetrachloride does not. (05 marks) 4. The table below shows the melting points of some of the elements in Period 3 of the Periodic Table . Elements 11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar Melting point (ᵒC) 98 650 660 1,423 44 120 -101 -189 a) State what meant by the …