Posted by isoka on Sunday, September 26, 2010 at 5:56pm.
An unknown compound contains only carbon, hydrogen, and oxygen . Combustion of 2.50 g of this compound produced 3.67 g of carbon dioxide and 1.50 g of water.
What is the empirical formula of a substance that contains 8.33×10−2 mol of carbon, 0.167 mol of hydrogen, and 8.32×10−2 mol of oxygen?

C hemistry  DrBob222, Sunday, September 26, 2010 at 6:06pm
Are there two problems here.
#1.
Convert 3.67 g CO2 to g C, then divide by 2.50 to obtain %C.
Convert 1.50 g H2O to grams H and divide by 2.50 to convert to %H (after multiplying by 100, of course).
Now take a 100 g sample which gives you the percents in grams, convert g C to moles C, convert g H to moles H.
To find O, add percent C and percent H and subtract from 100 nd convert g O to moles.
Then find the whole number ratios of C, H, and O to each other with the smallest number being no less than 1.
Post your work if you get stuck. 
C hemistry  emily chambers, Sunday, September 26, 2010 at 6:29pm
sorry just this one
What is the empirical formula of a substance that contains 8.33×10−2 mol of carbon, 0.167 mol of hydrogen, and 8.32×10−2 mol of oxygen? 
C hemistry  DrBob222, Sunday, September 26, 2010 at 7:27pm
Most of the work is done since you already have C, H, and O in the form of moles. Divide by the smallest number (so that the smallest number ratio will be 1.000), then divide the other numbers by the same small number. See if you get CH2O? That's what I have.