difference between empirical and molecular

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Lucy Weaver 1K
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difference between empirical and molecular

Postby Lucy Weaver 1K » Thu Oct 08, 2020 4:33 pm

How do you know if the empirical and molecular formula are equal?

manisha_joseph_1H
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Re: difference between empirical and molecular

Postby manisha_joseph_1H » Thu Oct 08, 2020 4:43 pm

Once you have calculated the empirical formula of the specified compound, calculate the molar mass of the empirical formula. Then, compare this to the molar mass given in the question for the specified compound. If these two values are the same, then the empirical and molecular formulas are the same. If not, then you can divide the molar mass of the compound given by the molar mass of the empirical formula to get the factor by which the empirical formula needs to be multiplied by in order to get the molecular formula. Hope this helps!

Anna Yakura 2F
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Re: difference between empirical and molecular

Postby Anna Yakura 2F » Thu Oct 08, 2020 4:43 pm

Usually in that case, in the question, there will be a molar mass listed for that molecular or compound. After getting your empirical formula, you find out the molar mass (add up all the molar masses for each element), and compare it to the molar mass in the question. If they match, then your empirical formula is also your molecular formula. If they don't, you need to figure out what integer you need to multiply by in order for those masses to match. (for ex, if you calculated 100g for the molar mass but the question gives you 200g, you need to multiply your stoichiometric coefficients by 2). I don't know if I explained this correctly but hope it helps.

Lauren Mungo 1K
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Re: difference between empirical and molecular

Postby Lauren Mungo 1K » Thu Oct 08, 2020 4:46 pm

Hi! You would have to know what the molar masses are of the molecular formula and empirical formula. The empirical formula will normally have a smaller molar mass as it just represents the ratio of molecules. If the two formulas are equal to each other, then their molar masses will be the same.

Violet Kwan 3H
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Re: difference between empirical and molecular

Postby Violet Kwan 3H » Thu Oct 08, 2020 4:50 pm

If the molar mass of the molecule is equal to the total mass of the empirical formula that you calculated, then they are the same. If it is different, then divide the given molar mass by your calculated empirical formula mass to find the scalar factor. Then adjust all the atom numbers of the empirical formula accordingly to determine the molecular formula.

Rylee Mangan 1K
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Re: difference between empirical and molecular

Postby Rylee Mangan 1K » Thu Oct 08, 2020 4:55 pm

In order to determine if they are equal or different you would need the molar mass of the initial (usually empirical but not always) equation and then compare that to the molecular mass. The molecular mass must be given in the question.

Eq: Molecular mass / initial molar mass found
and if it does not equal 1, (for example - it equals 2) you would multiply the initial formula by that number (2) to get the molecular formula

Lily Anne Garcia 1C
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Re: difference between empirical and molecular

Postby Lily Anne Garcia 1C » Thu Oct 08, 2020 5:20 pm

After calculating the empirical formula, you can use the periodic table to calculate its mass. If the directions are telling you to find the molecular formula, they should have given you a mass for that compound. If you divide the mass of the molecular formula by the mass of the empirical formula and the answer is 1, then the two formulas are the same. However, they are rarely the same. It usually will come out to a value greater than one which means that you have to multiply the subscripts of the empirical formula by whatever number you got. For example, if the empirical formula was C6H6O2 and the number you got after dividing the mass was 2, then the molecular formula would be C12H12O4.

AmyHo2K
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Re: difference between empirical and molecular

Postby AmyHo2K » Thu Oct 08, 2020 5:23 pm

Hi, it'll be equal if the empirical mass is equal to the molecular mass given.

Namratha Gujje
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Re: difference between empirical and molecular

Postby Namratha Gujje » Thu Oct 08, 2020 5:34 pm

You would know that the empirical and molecular formulas are equal if they have the same molar mass. When you are solving a problem that asks something about both the molecular and empirical formula you should given the molar masses for both or should have enough information to solve for them.

Michael Sun Dis 3G
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Re: difference between empirical and molecular

Postby Michael Sun Dis 3G » Thu Oct 08, 2020 6:03 pm

Assuming the question you're answering gives you the molar mass of the actual molecule, you should first find the molar mass of the empirical formula, and then divide the molar mass of the molecule by it. If the factor you get from this division is 1, they would be equal. If not, multiply each element in the empirical formula by the factor, and you should get the molecular formula.

Funmi Baruwa
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Re: difference between empirical and molecular

Postby Funmi Baruwa » Fri Oct 09, 2020 11:13 am

The empirical formula is the ratio of atoms while the molecular formula gives you the actual amount of atoms in a molecule, so they won't be equal.

Keshav Patel 14B 2B
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Re: difference between empirical and molecular

Postby Keshav Patel 14B 2B » Fri Oct 09, 2020 11:21 am

Empirical formula sets the varying ratios of molecules to make up a formula while the molecular formula specify the specific amount of each molecule.

905409193
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Re: difference between empirical and molecular

Postby 905409193 » Sat Oct 10, 2020 6:38 pm

L-Dopa, a drug used for the treatment of Parkinson’s disease, is 54.82% C, 5.62% H, 7.10% N, and 32.46% O, and has a molar mass of 197.19 g/mol.
This problem from Empirical and Molecular Formulas Post-Module Assessment makes it clear that it is possible to have an empirical formula equivalent to the molecular formula.

Jonathan3B
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Re: difference between empirical and molecular

Postby Jonathan3B » Sat Oct 10, 2020 9:31 pm

Since molecular equations are basically some sort of multiple of the empirical equation, find out what that multiple is (should be fairly easy given you have both equations) and then divide the molar mass of the molecular equation by that multiple and if it equals the molar mass of the empirical equation, you know they are equal.

Joanna Huang
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Re: difference between empirical and molecular

Postby Joanna Huang » Sat Oct 10, 2020 10:09 pm

The question will usually state the final molar mass of the product, and ask you to calculate the molecular formula of that product. You will then take the empirical formula that you have calculated, and then find the molar mass of the empirical formula. Once that is done, compare the molar mass of the empirical formula to the molar mass of the product given in the problem. If the masses are extremely close of equal to one another, then the empirical formula would be equal to the molecular formula. If it is not equal, divide the molar mass of the product by the molar mass of the empirical formula to obtain the multiplying factor. Take that factor, and multiply it by all the subscripts in the empirical formula, and you should get the molecular formula.

Scot Widjaja Dis 1J
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Re: difference between empirical and molecular

Postby Scot Widjaja Dis 1J » Sun Oct 11, 2020 9:15 am

If the empirical formula mass is equal to the molecular formula mass, then empirical formula equals molecular formula.


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