Empirical to Molecular Formulas  [ENDORSED]

Moderators: Chem_Mod, Chem_Admin

Sears 4A
Posts: 36
Joined: Tue Feb 05, 2019 12:15 am

Empirical to Molecular Formulas

Postby Sears 4A » Sun Oct 06, 2019 11:14 am

I understand how to find empirical formulas, but am unclear on how you would transfer that into a molecular formula. What kind of further information do you need to find the true molecular formula?

Joowon Seo 3A
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am
Been upvoted: 1 time

Re: Empirical to Molecular Formulas

Postby Joowon Seo 3A » Sun Oct 06, 2019 11:19 am

You would need the molar mass of the molecule you are trying to find. Then you would divide that molar mass by the molar mass of the empirical formula and get a number. If the number is like 2.9 or 5.1, you can round it to a whole number. If it is not a whole number, I suggest checking your work because something might be wrong in your calculations. Then multiply that whole number with each of the atoms in the empirical formula, and then you get the molecular formula.
I hope this helps.

Rebekah Alfred 1J
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am
Been upvoted: 1 time

Re: Empirical to Molecular Formulas

Postby Rebekah Alfred 1J » Sun Oct 06, 2019 11:27 am

To find the molecular formula, you divide the molar mass of the compound by the molar mass of the empirical formula. This will give you a whole number or a number very close to a whole number. You then multiply all the subscripts in the empirical formula by the whole number you just found. Therefore, the further information you need to find the true molecular formula is the molar mass of the compound and the molar mass of the empirical formula.

Asia Yamada 2B
Posts: 92
Joined: Wed Sep 30, 2020 9:36 pm

Re: Empirical to Molecular Formulas

Postby Asia Yamada 2B » Wed Oct 07, 2020 1:56 am

Once you’ve found the empirical formula, you need to calculate its molar mass. The molar mass of the molecular formula will be given. You divide the molecular molar mass by the empirical molar mass and this will result in a whole number, approximately. To find the molecular formula, you multiply each of the subscripts in the empirical formula by that whole number.

Alexa Pham 1D
Posts: 69
Joined: Wed Sep 30, 2020 10:03 pm

Re: Empirical to Molecular Formulas  [ENDORSED]

Postby Alexa Pham 1D » Wed Oct 07, 2020 8:53 am

You would need to find the factor by which you multiply the subscripts of the empirical formula with. This can be found by dividing the molar mass of the molecular formula (usually given in the problem) by the molar mass of the empirical formula! Hope that helps.

Luveia Pangilinan 1A
Posts: 85
Joined: Wed Sep 30, 2020 9:48 pm
Been upvoted: 1 time

Re: Empirical to Molecular Formulas

Postby Luveia Pangilinan 1A » Wed Oct 07, 2020 9:11 am

I think everyone has already answered your question. But to put it simply, use the molar mass and compare the empirical molar mass. If they match, molecular formula and empirical formula are the same. Otherwise, you'll have to divide the empirical mass by the given overall molar mass. Whatever closest whole number you get, you will multiply that to your current empirical subscripts. :D Hope this helps

Chem_Mod
Posts: 19540
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 882 times

Re: Empirical to Molecular Formulas

Postby Chem_Mod » Wed Oct 07, 2020 10:23 am

LuveiaPangilinan 2C wrote:I think everyone has already answered your question. But to put it simply, use the molar mass and compare the empirical molar mass. If they match, molecular formula and empirical formula are the same. Otherwise, you'll have to divide the empirical mass by the given overall molar mass. Whatever closest whole number you get, you will multiply that to your current empirical subscripts. :D Hope this helps


To clarify one must divide the molar mass of the molecule by the molar mass of the empirical formula.


Return to “Empirical & Molecular Formulas”

Who is online

Users browsing this forum: No registered users and 1 guest