chemistry
posted by JackS on .
Hi can you help me balance these equations? I did the first three but I don't think I did them right...
1. C3H8+O2> CO2
+H20
I balanced this one like this: C3H8+5O2>3CO2+4H20
2. C4H10+O2>CO2+H20
balanced: C4H10+O2>2CO2+5H20
3. C8H18+O2>CO2+H20
balanced: C8H18+O2>4CO2+9H20
and for the last one I am having trouble with...
4. C10H22+O2>CO2+H20

hey does the H2O suppose to be water or 20 hydrogens...because I can help
you if you can clarify. 
#1 you balanced correctly.
2. C4H10+O2>CO2+H20
balanced: C4H10+O2>2CO2+5H20
#2 is not right. You can tell if the equations are balanced or not by simply checking them. I see 4 C on the left and only 2 on the right so it isn't correct right off the bat. Here is how you do them. First, separate them so you can see what is going on.
C4H10 + O2 ==> CO2 + H2O
We have 4 C on the left so we need to place a four on CO2 like this.
C4H10 + O2 ==> 4CO2 + H2O
We have 10 H on the left so we need to place a 5 for H2O, like this.
C4H10 + O2 ==> 4CO2 + 5H2O
The only thing left is O2. SO, count up what we need on the right. I see 8 O from 4CO2 and another 5 O from 5 H2O and that makes a total of 13. Ugh!. An uneven number. What I do is just put the fraction in because 13/2*O2 would be 13 O atoms. Like this.
C4H10 + (13/2)O2 ==> 4CO2 + 5H2O
No, we can't leave the equation like that because it has a fraction, BUT we can get rid of the 1/2 by multiplying everything by 2. Like this.
2C4H10 + 13O2 ==> 8CO2 + 10H2O
Now, let's check it. I see 8 C on the left and 8 C on the right.
I see 20 H on the left and 20 H on the right.
I see 26 O on the left and on the right I see 16 from the CO2 and another 10 from H2O and that makes 26. Everything balanced.
I will leave the other two for you. (The other way to do these; when the numbers don't work and you are off by just one O, then multiply everything by 2, count up what you need on the right and add that number on the left.) Try the others and repost if you have trouble but tell us what you don't understand.
3. C8H18+O2>CO2+H20
balanced: C8H18+O2>4CO2+9H20
and for the last one I am having trouble with...
4. C10H22+O2>CO2+H20 
the answer to # 4 is :
2C10H22+31O2>20CO2+22H20 
i guess H20 is water...so your last equation would be....2C10H22+31O2>20CO2+22H2O

Logan has balanced the last equation. #3. is not balanced.

thanks
I tried doing the other two. And then I did an atom inventory the numbers of the products side and reactants side did not seem to match
can you guide me through the problems again please? It helps when you explain it to me.
thanks 
Thank you, Logan