## Post-Module Assessment Q22

Sana_Mian_3G
Posts: 30
Joined: Fri Sep 28, 2018 12:23 am

### Post-Module Assessment Q22

Find the molecular formula for 39.43% C, 52.58% O, and 7.88% H.
I was wondering if someone could explain what the steps are after we find the moles through the empirical formula?
These are the moles I got:
C: 1 mol
O: 1.001 mol
H: 2.376 mol

Also, could someone post the answer so I can check.
Last edited by Sana_Mian_3G on Thu Oct 04, 2018 10:22 pm, edited 1 time in total.

Duby3L
Posts: 72
Joined: Fri Sep 28, 2018 12:26 am

### Re: Post-Module Assessment Q22

You would divide by the smallest moles each element. Once you do so, you'll have to make sure they are whole numbers which could mean you have to multiply by a number that will give you whole numbers.

Duby3L
Posts: 72
Joined: Fri Sep 28, 2018 12:26 am

### Re: Post-Module Assessment Q22

After calculating the empirical formula you divide the molar mass of the compound by the empirical formula.

Ariel Cheng 2I
Posts: 67
Joined: Fri Sep 28, 2018 12:29 am

### Re: Post-Module Assessment Q22

After finding the empirical formula (C5H12O5), calculate its molar mass which should be about 152.15 g/mol.

The question should give the molar mass of the compound. Divide that number by the 152.15 g/mol you just calculated to find the ratio between the molecular and empirical formula. Use that ratio to determine the molecular formula from the empirical formula!