A LEVEL Chemisrty June 2020 Paper 2 Questions From Real Exams

A LEVEL Chemisrty June 2020 Paper 2 Questions From Real Exams 1 2 Section A Answer all questions in this section. Do not write outside the box This question is about 1-chloropropane. . Define the term standard enthalpy of formation. [2 marks] . The equation for a reaction used to manufacture 1-chloropropane is 3CH3CH2CH2OH(l) + PCl3(l)  3CH3CH2CH2Cl(l) + H3PO3(s) The enthalpy change for this reaction, ΔH, is –114 kJ mol–1 Table 1 contains some standard enthalpy of formation data. Table 1 Substance PCl3(l) CH3CH2CH2Cl(l) H3PO3(s) ∆fH o / kJ mol–1 –339 –130 –972 Calculate a value for the standard enthalpy of formation of propan-1-ol using the enthalpy change for the reaction and data from Table 1. [3 marks] Standard enthalpy of formation kJ mol–1 0 1 0 1 0 1 lOMoAR cPSD| 3 *03* IB/M/Jun20/7404/2 Downloaded by charity nimo () 3 4 . 1-chloropropane can also be produced by the reaction between propane and chlorine in the presence of ultraviolet light. State why ultraviolet light is needed for this reaction to occur. Give an equation for each propagation step in the formation of 1-chloropropane from propane. Do not write outside the box [3 marks] Why ultraviolet light is needed Propagation step 1 Propagation step 2 . The C–Cl bond in 1-chloropropane is polar because carbon and chlorine have different electronegativities. Define the term electronegativity. [1 mark] Question 1 continues on the next page Turn over ► 0 1 0 1 lOMoAR cPSD| 4 *04* IB/M/Jun20/7404/2 Downloaded by charity nimo () 5 14 . Ammonia reacts with 1-chloropropane to form propylamine. Name and outline the mechanism for this reaction. [5 marks] Do not write outside the box Name of mechanism Outline of mechanism