Title 9701_s25_qp_12.pdf ✅

3 © UCLES 2025 9701/12/M/J/25 [Turn over 4 The reaction between sulfur dioxide and oxygen has the equation shown. 2SO2(g) + O2(g) 2SO3(g) H = –197 kJ mol–1 1.0 mol of SO2 and 1.0 mol of O2 are placed in a closed container and heated to a constant temperature. At this temperature, 0.8 mol of SO3 are present in the equilibrium mixture. Which statement is correct? A The equilibrium partial pressure of SO2 is greater than the equilibrium partial pressure of O2. B Kp has units of mol dm–3. C At a lower temperature, the equilibrium amount of SO3 is lower than 0.8 mol. D The mole fraction of SO3 is less than 0.8. 5 ‘Red lead’ is a red pigment with the formula Pb3O4. Every formula unit of ‘red lead’ is the same. Each formula unit contains three lead ions and four oxide ions. Lead has two different oxidation states in ‘red lead’. What are the oxidation states of lead in ‘red lead’? A +1 and +2 B +1 and +3 C +2 and +4 D +2 and +6 6 Some standard enthalpy of combustion data are given. substance standard enthalpy change of combustion / kJ mol–1 C(s) –394 H2(g) –286 CH3OH(l) –726 Using these data, what is the enthalpy change of formation of methanol? A –240 kJ mol–1 B –46 kJ mol–1 C 46 kJ mol–1 D 240 kJ mol–1 7 Which row is correct? smallest bond angle largest bond angle A H2O NH3 BF3 B BF3 NH3 H2O C NH3 H2O BF3 D H2O BF3 NH3