Expert: John Dobiecki - 4/1/2005

Question
how do you answer:

this is an unbalanced equation for an organic compound but i dont know how to balance it.

the X and Y are suppose to be little and what i have to find out

PLEASE HELP thanks!

CxHy + O2 --> CO2 + H2O

After burning, 5.86 grams of carbon dioxide and 1.37 grams of water were collected. Find the empirical formula of the compound.

Answer
Hi Anna,

I usually don't answer homework type questions, but I'll do it for you this one time.

Step one:  Determine how many moles of CO2 and H2O you ended up with - 1 Mole CO2 = 44g; 1 Mole H2O = 18g
For CO2 5.86g/44g=0.13M  for H2O 1.37g/18g=0.076.

Step two:  Now let's see how much of each Carbon ("C"), Hyhdrogen ("H") and Oxygen ("O") we have on the left side of the reaction equation:

CO2 =C(0.13) and O(2x0.13) or 0.13moles C and 0.26moles O
H20 = H (2x0.076) and O (0.076) or 0.15 moles H and 0.076 mole O.

Step 3:  Remember that the "x" and "y" represent the "moles" of each element all we need to do is plug in those number figured out in stpe two.  So for Carbon ("C") x = 0.13 and for Hydrogen ("H") y = 0.076.

I'll be honest this is kinda of a different kind of problem that I would have given when I taught Organic 28 years ago.  I'm pretty sure this is the right answer, but 28 years is a long time.  Do me a favor and let me know if the answer is right.

Thanks and good luck

jd