Question

If 2.0 moles of A and 3.0 moles of B react according to the hypothetical reaction below, how many moles of the excess reactant will be left over at the end of the reaction? A + 2B → AB2 (3 points) 1.0 mol B left over 0.50 mol A left over 1.5 mol B left over 1.5 mol A left over

Answer 1

.5 mol of A will be left over since 1.5 mol of A will be used for every 3 mol of B due to the 2:1 ratio established by the formula.

Answer 2

Answer: The correct answer is 0.50 mol A left over.

Explanation:

Excess reactant is defined as the reactant which is present in excess in the reaction and does not predict the formation of product.

Limiting reactant is defined as the reactant which is present in limiting amount and which limits the formation of products.

For the given chemical reaction:

$A+2B\rightarrow AB_2$

By Stoichiometry of the reaction:

2 moles of B is reacting with 1 mole of A.

So, 3 moles of B will react with = $\frac{1}{2}\times 3=1.5mol$ of A.

As, the given moles of A is more than the required moles. So, it is present in excess and is considered as an excess reagent.

Amount of excess reagent left (A) = 2 - 1.5 = 0.5 moles

Thus, the correct answer is 0.50 mol A left over.