The reaction 2SO + O2 ¨ 2SO3 is exothermic. (a) How will a rise in temperature affect the yield of SO3 in an equilibrium mixture of the three gases? (b) Will an increase in pressure raise or lower the yield? (c) In what possible way can the speed of the reaction be increased at moderate temperatures?

Question

The reaction 2SO + O2 ¨ 2SO3 is exothermic.  (a) How will a rise in temperature affect the yield of SO3 in an equilibrium mixture of the three gases?  (b) Will an increase in pressure raise or lower the yield?  (c) In what possible way can the speed of the reaction be increased at moderate temperatures?

DrBob222 · Answer

2SO + O2 --> 2SO3 + heat

Le Chatelier's Principle tells us, in simple terms, that a system in equilibrium will shift so as to undo what we've done. So if the heat is evolved and we increase the temperature the reaction will shift so as to use up the heat we've added. Therefore, the reaction will shift to the ...... (SO3) will ...... while SO and O2 will .....

b) An increase in pressure will make it shift to the side with fewer moles. There are three moles on the left and 2 on the right. So it will shift to the ..... produce (more/less) SO3 which will (increase/decrease) the yield.