Post-Module Assessment Q22

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

Post-Module Assessment Q22

Postby Sana_Mian_3G » Thu Oct 04, 2018 10:06 pm

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

Postby Duby3L » Thu Oct 04, 2018 10:10 pm

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

Postby Duby3L » Thu Oct 04, 2018 10:12 pm

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

Postby Ariel Cheng 2I » Fri Oct 05, 2018 8:16 am

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!


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