Posted by Will on Tuesday, October 13, 2009 at 8:55pm.
Could someone please tell me if I did this question correctly?
An incomplete combustion reaction of 12.125 grams of propane proceeds as follows: 2C3H8 + 11O2 = 3CO2 + 4H2O + 2CO + C(s).How many grams of solid carbon residue are produced as a product?
my answer:
known:
molar mass of propane=48.91g/mol
molar mass of carbon= 12.01g/mol
Step 1)
The balanced chemical equation for "2C3H8 + 11O2 = 3CO2+ 4H2O + 2CO + C"
is "7C3H8 + 22O2 = 6CO + 284H2O + 4CO + 11C."
Step 2)
Convert 12.125 grams of propane to moles.
12.125g/(48.91g/mol)
=.2479mol
step 3)
The ratio of propane to carbon dioxide is 7:11(or 1 to 1.5714). Therefore, for every mole of propane there will be 1.5714mol of carbon.
1.5714(.2479mol)=.3896mol of carbon.
step 4)
Convert back to grams.
.3896mol( 12.01g/mol)
= 4.679g
Answer:
In the given reaction, 4.679g of solid carbon will be produced.
Thanks for your help.

chemistry  DrBob222, Tuesday, October 13, 2009 at 10:43pm
2C3H8 + 11O2 = 3CO2 + 4H2O + 2CO + C(s).
The equation isn't balanced; therefore, any calculation based on an unbalanced equation will not be correct.
C balanced.
H does not. There are 16 atoms on the left and 8 on the right.
O does not. There are 22 atoms on the left and 12 on the right. 
chemistry  Will, Wednesday, October 14, 2009 at 12:11am
In step 1), I balanced the equation to "7C3H8 +22O2 >> 6CO2 + 28H2O +4CO +11C". Is this not correct, along with the rest of my answer?
Excuse the my typo in my original when I put the coefficient for H2O as 284 when it should be 28.
Thank you.