2SO3(g) = 2SO2(g) + o2(G) H= 197 kj

For the reaction shown above, describe the changes that will occur to the number of moles of SO3 under the following conditions:
a.) Additional oxygen is added to the reaction vessel.
b.) The pressure in the reaction vessel is decreased by increasing its volume.
c.) The pressure is increased by the addition of helium gas.
d.) The temperature is increased.
e.) Oxygen gas is removed.

a) Adding O2 will cause the reaction to go left to use up some of the excess. That will produce more SO3.

b) A decrease in pressure will cause the reaction to go right since there are more gas moles on the right side of the equation (increasing the no. of gas moles will help offset the pressure decrease caused by expanding the volume). Going right would use up some SO3.

c) The reaction would go left to decrease the no. of gas moles in the system. Going left would produce more SO3.

d) The reaction is endothermic (+197 kJ) so het is a reactant. Adding more heat will produce more product (go right), but that will use up some SO3.

e) Removal of the product O2 would cause the system to go right in an attempt to replace some of what was removed. Going right uses up SO3.