[Shaggith55]

My chemistry professor gave the class this problem: 1. A+B Product 2. 2A+B  Product. In equation 1, A is in excess. In equation 2, B is in excess. How many moles of A and B are in the mix?

My whole class agonized over this problem for awhile before he allowed us to continue the class. He wanted to see if it was too difficult. For my class, it was. He did not give us the answer, so now I'm curious. Can anyone here solve this problem? (Including the steps you took would be appreciated because I want to know how you got it)

[Borek]

1. A+B Product 2. 2A+B  Product. In equation 1, A is in excess. In equation 2, B is in excess. How many moles of A and B are in the mix?

I am not convinced I understand the question correctly, but sounds to me like there is no exact answer. You can tell in what range the ratio of A and B is, not what their exact values are.

Wording of the question is not helpful though. I take it to mean:

We have a mixture of A and B, they can react in two ways:

1. A+B Product
2. 2A+B  Product

If only first reaction would take place, A would be in excess. If only second reaction would take place, B would be in excess. What are possible compositions of the mixture?

[Shaggith55]

My professor told us this was all the information he'd give. He was asking what their molar ratios were, though. I'm sure he was not expecting exact values. Is this possible to do? I'm sure this was the question because I wrote it down.

[Borek]

Not much that I can add beyond what I already wrote, we can use stoichiometry to calculate maximum and minimum ratio of A and B. In other words: there are infinitely many A:B ratios that fit the scenario, but they all lie in a well defined interval.