How many moles of water can be produced from 2.5 moles of propane ( C3H8) ?

Answer 1

We will assume this question is asking about a complete combustion reaction.

This means the propane is reacting with oxygen gas (O₂) to produce carbon dioxide (CO₂) and water (H₂O), so the unbalanced equation looks like this:

C₃H₈ +O₂ ⇒ CO₂ + H₂O

Now we must balance this equation in order to find out the ratio of moles for our reactant and product in question (i.e. propane and water)

To balance combustion reactions, I usually start with carbon and hydrogen atoms, then oxygen if we have an even number:

3 carbons in propane means we multiply CO₂ by 3.

C₃H₈ +O₂ ⇒ 3CO₂ + H₂O

8 hydrogens means we multiply the pairs of hydrogen in water by 4 to get 8 on the product side.

C₃H₈ +O₂ ⇒ 3CO₂ + 4H₂O

Now we add up our oxygen atoms on the product side; looks like we have 10 total which makes the next step easy!

10/2 = 5, so

C₃H₈ + 5O₂ ⇒ 3CO₂ + 4H₂O

is our balanced equation.

A balanced equation gives you the ratio of products to reactants; for every 1 mole of propane we get 4 moles of water. So the answer is going to be our moles of propane times 4.

2.5*4 = 10 moles water