Predict the direction of the net reaction in each of the following system, as a result of increasing the temperature. Delta H is an indicator or whether the reaction releases heat delta H(-), or heat is absorb delta H(+). Write where the direction shifts.

Question

a)3O2(g)=2O3(g) H=+284kJ
b)2SO3(g)+O2=2SO5(g) H=-198.2kJ
c) 2H2O(g)=2H2(g)+O2 H=+584kJ

Answer 1

Le Chatelier's Principle says, in simple language, a system in equilibrium will try to undo what we do to it.
for a.
The +284 means the system is endothermic which means the system absorbs energy as it reacts from left to right. So, if we increase heat, the system will try to use up the added heat. How can it do that? The only way (you have only three choices in these problems--shift to right, shift to left, no change) it can do that is to react to produce more products (shift to the right). I find it helpful on problems where heat is indicated with a delta value to rewrite the equation. For a that will be
3O2(g) + heat ==> 2O3(g) I think it makes it easier to see that shifting to the right is using up the heat.
For one with a -delta H, (b for example) I would write it this way.
2SO3(g) + O2(g) ==> 2SO5(g) + heat. By the way, b is not balanced.