Question

Consider this hypothetical reaction: A+4B→C+5D.

Assume that the equation is balanced.

In which reactant mole ratios will reactant B be the limiting reagent?

Responses

A/5B

uppercase A over 5 uppercase B

A/2B

uppercase A over 2 uppercase B

A/4B

uppercase A over 4 uppercase B

2A/9B

2 uppercase A over 9 uppercase B

Answer 1

Reaction needs 4 B per 1 A, so B is limiting when the available B/A ratio is less than 4. Equivalently, A/B > 1/4.

Evaluate each given A/B:

- A/5B = 1/5 = 0.20 < 0.25 → B is in excess (A limiting)
- A/2B = 1/2 = 0.50 > 0.25 → B is limiting
- A/4B = 1/4 = 0.25 = stoichiometric (neither limiting)
- 2A/9B = 2/9 ≈ 0.222 < 0.25 → B is in excess (A limiting)

So only A/2B makes B the limiting reagent.