Question

Water is produced from the reaction of hydrogen and oxygen gas, according to the equation below. What is the excess reactant in the reaction of 4.2 moles of hydrogen with 3.0 moles of oxygen?
2H2(g) + O2(g) = 2H2O(L)

Select one:
a. Water
b. Oxygen
c. No excess reactant
d. Hydrogen

Answer 1

Explanation:

Mole ratio of Oxygen to Hydrogen gas = 1 : 2.

If we use 3.0 moles of oxygen gas, we would need 3.0 * 2 = 6.0 mol of hydrogen gas.

However we only have 4.2 mol of hydrogen. Therefore hydrogen is limiting and oxygen is in excess. (B)