Empirical Formula

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Leslie Contreras 1D
Posts: 35
Joined: Fri Apr 06, 2018 11:02 am

Empirical Formula

Postby Leslie Contreras 1D » Wed Apr 11, 2018 2:30 pm

The Molar mass is 84g.mol and its empirical Formula is CH2. What is its Molecular Formula?
I'm not sure how to start but I understand the process?
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Screen Shot 2018-04-11 at 2.24.28 PM.png
Screen Shot 2018-04-11 at 2.24.28 PM.png

KristinaNguyen_1A
Posts: 30
Joined: Fri Apr 06, 2018 11:04 am

Re: Empirical Formula

Postby KristinaNguyen_1A » Wed Apr 11, 2018 3:34 pm

I believe that since they give you the molar mass and the empirical formula, you will need to find the molar mass of the empirical formula:

C=12.01
H2=2(1.008)
CH2= 14.026

And then you find the ratio: 84g*mol^-1/14.026g*mol^-1

That will give you a value of 5.98888 so it is approximately 6

You will then multiply: 6(CH2) so you will end up with a molecular formula of C6H12

Jamie Reniva 1J
Posts: 14
Joined: Wed Nov 15, 2017 3:00 am

Re: Empirical Formula

Postby Jamie Reniva 1J » Wed Apr 11, 2018 4:27 pm

Since the empirical formula is given, you can find the molar mass of the empirical formula!
C=12.01
H=1.008 (since it's H2, you multiply 1.008 times 2)
Molar mass of CH2=14gCH2 (2 sig figs from the equation)

Always remember that you need to divide actual/theoretical
So our actual= 84g.mol^-1
theoretical= 14.026g.mol^-1
(84g.mol^-1)/(14.026g.mol^-1)= 6

Once we get the number by dividing actual to theoretical we multiply it to our empirical formula!

6(CH2)

So the molecular formula is C6H12


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