Kirsten is in her lab, and reacts two unknown gases (A(g) and B(g)) to get nitrogen dioxide (NO2). Using her data, she is able to write the following balanced equation:

Question

2A(g) + B(g) --> 2NO2(g)
If she started with 8 L of A(g) and 3 L of B(g), how many liters of NO2(g) would she get? [Assume everything is at STP.]

2 L
3 L
4 L
6 L
8 L

Answer 1

When gases react to produce a gas, we need not go through the mol step; i.e., we can use liters as if liters were mols.
You can see this is a limiting reagent problem. It takes twice as much A as B; therefore, it would take 4 L of B to react with 8 L of A and we don't have 4 L of B. So I guessed wrong. 3 L of B will require 6 liters of A and we have more than enough. So B is the limiting reagent and all of B reacts. How much of the product will be formed? And you have your answer.