Question

30)Consider the same reaction:

4As(s) + 3O2(g) ĺ 2As2O3(s)
Suppose we start a reaction with 5.2 mol of As and 6.0 mol of O2 ? Which reactant is in excess?
A)No reactant is in excess
B)As2O3
C)O2
D)As

Answer 1

Step-by-step explanation:

To determine which reactant is in excess, we need to compare the mole ratio of the reactants in the balanced chemical equation to the actual mole ratio of the reactants given.

The balanced equation shows that 4 moles of As react with 3 moles of O2 to produce 2 moles of As2O3. This gives a mole ratio of As to O2 of 4:3.

Using the given amounts, we can calculate the mole ratio of As to O2:

moles of As = 5.2 mol

moles of O2 = 6.0 mol

mole ratio of As to O2 = 5.2 mol / 6.0 mol = 0.87

Comparing the mole ratios, we see that the actual mole ratio of As to O2 is less than the mole ratio in the balanced equation. This means that O2 is in excess, and As is the limiting reactant.

Therefore, the answer is (C) O2.