Question

How many water molecules (H2O) can be produced from 6 molecules of hydrogen gas (white) reacting with 6 molecules of oxygen gas (red)? Which reactant is the limiting reactant?

Answer 1

I think you can only have 3 water molecules because you need 2 hydrogen molecules in every water molecule and you have 6 hydrogen molecules so 6/2=3 and the reactant that is limited would be hydrogen since it limits the amount of water molecules you can have

Answer 2

Answer: The hydrogen gas is the limiting reagent and 6 molecules of water are produced.

Explanation:

We are given:

Molecules of hydrogen gas = 6 molecules

Molecules of oxygen gas = 6 molecules

The chemical equation for the reaction of hydrogen gas and oxygen gas follows:

$2H_2+O_2\rightarrow 2H_2O$

By Stoichiometry of the reaction:

2 molecules of hydrogen gas reacts with 1 molecule of oxygen gas

So, 6 molecules of hydrogen gas will react with = $\frac{1}{2}\times 6=3$ molecules of oxygen gas

As, given amount of oxygen gas is more than the required amount. So, it is considered as an excess reagent.

Thus, hydrogen gas is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

2 molecules of hydrogen gas produces 2 molecules of water

So, 6 molecules of hydrogen gas will produce = $\frac{2}{2}\times 6=6$ molecules of water

Hence, the hydrogen gas is the limiting reagent and 6 molecules of water are produced.