Propane gas (C3H8) reacts with Oxygen in a combustion reaction, producing Carbon dioxide and water.

Question

A) Write and Balance the following Word Equation: 

B) Using your balanced equation above, answer the following questions: in t chart below

How many moles of Oxygen gas are necessary to react with 4.50 moles of Propane?

and

1. How many moles of water are produced from the reaction of Propane with 9.0 moles of Oxygen?

Answer 1

This reaction is a combustion reaction.

Combustion reaction usually involve a carbon fuel plus oxygen gas (O₂). It yeids CO₂ and water vapor.

To remember propane as a 3 carbon molecules, I use the mnemonic Me Eat Peanut Butter.

( methane, ethane, propane, butane)

C₃H₈ + O₂ → CO₂ + H₂O

Now to balance

Since there are 3 cabons on the right, let's put a coefficient of 3 in front of CO₂ on the left.

Next balance the hydrogens by placing a 4 in front of the water molecule on the right.

Lastly there will be 10 oxygens on the right , therefore, place a 5 in front of the oxygen gas on the left.

C₃H₈ + 5O₂→ 3CO₂ + 4H₂O

Now

Given 4,5 moles propane

Find moles of oxygen gas

4.5 mol C₃H₈ X 5 moles O₂/1 mole C₃H₆ = 22.5 moles of O₂

Answer 2

a) Complete combustion of propane:

C₃H₈(g) + 5O₂(g) ==> 3CO₂(g) + 4H₂O(g) ... balanced equation

b) How many moles of O₂ are needed to react with 4.50 moles C₃H₈?

Look at the stoichiometry of the balanced equation. Note that the mole ration of O₂ to C₃H₈ is 5 : 1. We use this information to find the moles of O₂ needed.

4.50 moles C₃H₈ x 5 moles O₂ / 1 mole C₃H₈ = 22.5 moles of O₂ (3 sig.figs. based on 4.50 moles)

How many moles of H₂O are produced from the reaction of C₃H₈ with 9.0 moles of O₂?

Again, look at the stoichiometry of the balanced equation. Note that the mole ratio of H₂O to O₂ is 4 : 5. Use this information to find the moles of H₂O produced.

9.0 moles O₂ x 4 moles H₂O / 5 moles O₂ = 7.2 moles of H₂O produced. (2 sig.figs. based on 9.0 moles)

Answer 3

Combustion reactions are when you have a hydrocarbon reacting with O₂ and yielding CO₂ and H₂O so I would first write the unbalanced equation:

C₃H₈ + O₂ → CO₂ + H₂O

Then balance it:

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Notice that 1 mole of propane needs to react with 5 moles of O₂ so you can use the molar ratio to calculate moles of O₂:

(4.5•5 = 22.5)

Also notice that 5 moles of oxygen produces 4 moles of water so, again using the molar ratio:

(9•4/5 = 7.2)