Consider the reaction: N2O4(g) <--> 2NO2(g)

Question

delta H^o =58.576kJ; Keq =0.87 at 55degrees celsius
What is the effect of each of these changes upon the concentration of N2O4 at equilibrium?
a)increasing the temperature
b)increasing the volume
c) adding more NO2(g) to the system without changing pressure or temperature,
d) adding He gas to the container
e) adding a catlyst

Please help :)

Answer 1

This is Le Chatelier's Principle and you need to learn how to do these. They are simple but students often get confused. Most books give a very good definition but the problem is that most students don't follow it. My unorthodox definition is this. When a system in equilibrium is subjected to a stress the system will try to undo what we've done to it. That means if we add a reagent or heat it will shift so as to undo what we did.
Note that the reaction is endothermic; ie., we can write heat on the LEFT side. So if we increase T it will try to undo that. How can it do that? It can react more of the reactants to form more products. That's how it can use up the added heat. If we add N2O4 it will shift to the right in order to use up the added N2O4. With increasing pressure the system will shift to the side with the fewer moles of gas.
Post your answers if you want someone to check them.

Answer 2

Thank you! :)