Balancing Equations

[Panjandrum]

GRAR. I've got a hyuge exam on em soon, and I need help.
I thought I had a good enough idea of what I was doing, until I did an online activity..which...totally put my perspective at a slant.

See, here's my problem.
Ethane

C2H6 + O2 > CO2 + H20

C:2 C: 1
H:6 H: 2
O:2 O: 3

And then I start to balance.. (green spaces being where I put my numbers)

| | C2H6 + | | O2 > | | CO2 +| | H20

I first make 2 C in the second C box..


| | C2H6 + | | O2 > | 2 | CO2 +| | H20
So now:

C:2 C: 2
H:6 H: 2
O:2 O: 4

..Right? Now's where I'm beginning to be not so sure. When Oxygen is at two, it'd now be four, right?
So now I..


| | C2H6 + | 2 | O2 > | 2 | CO2 +| | H20
So now:

C:2 C: 2
H:6 H: 2
O:4 O: 4

Double the first Oxygen so now it is now also four! That's balanced..right?
sad 'Cause I thought at the end of these excercises they were supposed to be the exact same on both sides but on the online thingy (http://www.wfu.edu/~ylwong/balanceeq/combust.html) it would 'solve' equations with answers that had different numbers on each.

I'll try to finish this one, though..
I'll make the second Hydrogen multiply by three..
| | C2H6 + | 2 | O2 > | 2 | CO2 +| 3 | H20
So now the second Oxygen also changes?:

C:2 C: 2
H:6 H: 6
O:4 O: 4

........
????
Help please! gonk

[WereIdes]

What you've got here is wrong..

| | C2H6 + | 2 | O2 > | 2 | CO2 +| 3 | H20

C:2 C: 2
H:6 H: 6
O:4 O: 4 It should be 7.


What you need to do is this:

| 2 | C2H6 + | 7 | O2 > | 4 | CO2 +| 6 | H20

C:4 C: 4
H:12 H: 12
O:14 O: 14

There's only 1 O for each water.

Always save anything on its own (I.E. O2) for last. Work with the more complex stuff first and try and get most things to even numbers if you can manage it.

[bladehunterzero]

sometime there are exceptions to the rules.

the balance equations is:

2 C2H6 + 7O2 > 4CO2 + 6 H2O

i hope this helps

[Foetus In Fetu]

A balanced equation should have the same number of atoms on both sides, not the same numbers.

If you understand that these represent numbers of moles you can have something like 0.5 of an O2 but it's best to work with even numbers for now.

[pie_rat]

Don't panic, ok? It looks to me like your only problem was forgetting about the oxygen in water. Just look over your equations a little more carefully and you'll be ok. Remember that you're trying to balance out atoms, rather than molecules.

Just for the record, when I first learned balancing equations, I had a ton of trouble with it for some reason. I just couldn't seem to get it right. I had the same problem that you do - I'd just always miss out on one molecule of something that would make all my other balancing wrong. My teacher told me that I'd better forget about a career in science.
So right now I'm in my second year of medicinal chemistry at university... blaugh

[XxPowerMolochxX]

Foetus In Fetu

A balanced equation should have the same number of atoms on both sides, not the same numbers.

If you understand that these represent numbers of moles you can have something like 0.5 of an O2 but it's best to work with even numbers for now.

Indeed.