Question

A 6.378 gram sample of an organic compound containing C, H and O is analyzed by combustion analysis and 11.37 grams of CO2 and 4.655 grams of H2O are produced.

In a separate experiment, the molar mass is found to be 74.08 g/mol. Determine the empirical formula and the molecular formula of the organic compound.

Enter the elements in the order C, H, O

empirical formula =


molecular formula =

Answer 1

You will need to use gravimetric factor

Answer 2

to find the moles of C, and H present in the compound you can find the amount of O by simply finding the mass of C in CO2, O in H2O and then subtracting it from the mass combusted

Answer 3

do you know what gravimetric factor is?

Answer 4

\[Grams*\frac{Molecular Mass of Element of Interest}{Molecular Mass of Compound}\]

Answer 5

Using this,

Find moles of Hydrogen in Hydrogen in H2O
Find moles of Carbon in CO2

Add masses of C and H then subtract that from the initial mass combusted (6.378 g) to find the grams of Oxygen originally present in the sample

Then you need to convert the grams of H, C and O to moles

Then you take the moles that are the largest (or smallest I can't really remember) and divide each number of moles by that number. You should get whole numbers (if you get whole numbers like 3.5 just multiply by 2 to get an integer), this will equate to your empirical formula

Answer 6

Oh molecular formula all you need to do is first,

find the molecular mass of the emperical formula and divide it by the molecular formula it should give you some integer multiply that integer by all the # of atoms in the emperical formula to get the molecular formula

Answer 7

I think I explained the method to answer this pretty well so yeah if you have any questions ask now

Answer 8

wow thats great i got it thank you!