The gaseous substances A

_{2} and B

_{2} were mixed in a molar ratio 2:1 in a closed vessel at a temperature T

_{1}. When the equilibrium A

_{2}(g) + B

_{2}(g)

2AB(g) was established the number of heteronuclear molecules in a gas phase became equal to the total number of homonuclear molecules.

The question then asks the student to determine the equilibrium constant K

_{1}. I found it to be 7.2. I then answered quantitatively the remaining sections. The bit I need help on is this (I don't think any prior info is needed except

*perhaps* the K

_{c1} of 7.2):

Consider the reaction yield n=n

_{eq}(AB)/n

_{max}(AB) as a function of the initial molar ratio A

_{2} : B

_{2} = x : 1 at any fixed temperature (n

_{max} is the maximum amount calculated from the reaction equation). Answer the following questions qualitatively, without exact equilibrium calculations.

At what x the yield is extremal (minimal or maximal)?

What is the yield at: a) x tends to infinity; b) x tends to 0?

Draw the graph of n(x).

Now, consider the variable ratio A2 : B2 = x : 1 at a fixed total pressure.

At what x the equilibrium amount of AB is maximal?

I'm not really sure how to visualize this. For this last part, we should see the same minimal/maximal relationship as we see for the first part. The rest I need help on.