Question

What is the molar ratio for the following equation after it has been properly balanced?
____C3H8 + ____O2 arrow ____CO2 + ____ H2O

I'm really confused as to how I figure these problems out...

Answer 1

You just have to balance the number of atoms, so the amount of carbons on the right has to equal the number on the left.

Currently the unbalanced equation has:
3 carbons (C3H8) on the left and 1 carbon (CO2) on the right.
8 hydrogens (C3H8) on the left and 2 hydrogens (H2O) on the right
2 Oxygens (O2) on the left and 3 Oxygens (CO2 and H2O) on the right

Essentially to balance an equation you want the same number of hydrogens, carbons, and Oxygens on the left of the equation as on the right.

Tip always balance atoms that exist in only 1 chemical on the left and only 1 chemical on the right. In your case that means starting with carbon, hydrogen and then figuring out how to balance oxygen (it exists in two species on the right CO2 and H2O)


Example,

C2H6 + O2 -> CO2 + H2O
Balancing carbons

2 carbons on the left and 1 on the right so multiply CO2 by 2 we get

C2H6 + O2 -> 2CO2 + H2O

Now we have 2 carbons on the right an 2 carbons on the left

Balancing Hydrogen

6 hydrogen on the left 2 hydrogen on the right
so we multiply H2O by 3 to get 6 hydrogen on the right, this gives us

C2H6 + O2 -> 2CO2 + 3H2O


Balance oxygen
we have 2 oxygens on the left and 2*2 + 3*1 = 4 + 3 = 7 Oxygens on the right

Thus to balance oxygen we simply multiply O2 by 7/2, this gives us

C2H6 + 7/2 O2 -> 2CO2 + 3H2O

Now if you check you will see there are equal number of atoms of hydrogen, carbon and oxygen on both sides of the equation and therefore it is balanced

Answer 2

I hope this was helpful

Answer 3

Thank you so much! I understand how to do this now!