Molecular to Empirical Formula

Moderators: Chem_Mod, Chem_Admin

Abigail Menchaca_1H
Posts: 83
Joined: Sat Sep 07, 2019 12:19 am

Molecular to Empirical Formula

Postby Abigail Menchaca_1H » Tue Oct 08, 2019 11:40 pm

Does anyone know how to get the molecular formula being given only the empirical formula?

Jasmine Vallarta 2L
Posts: 84
Joined: Sat Aug 17, 2019 12:18 am

Re: Molecular to Empirical Formula

Postby Jasmine Vallarta 2L » Tue Oct 08, 2019 11:53 pm

Usually, you are given the molar mass of the molecular formula. You would have to divide: (molar mass of molecular formula)/(molar mass of empirical formula). You should end up with a whole number as the result. You then multiply that number to the subscripts of the compound, resulting in the molecular formula.

Lauren Tanaka 1A
Posts: 82
Joined: Sat Aug 17, 2019 12:18 am

Re: Molecular to Empirical Formula

Postby Lauren Tanaka 1A » Wed Oct 09, 2019 10:47 am

Usually to find the molecular formula given the empirical formula you are given the molar mass of the compound from mass spectrometry. You would then divide that mass by the total molar mass of the empirical formula. That number it gives you tells you how much to multiply each subscript of the compound by. You then multiply each subscript by that particular number and end up with the molecular formula.

Sofia Barker 2C
Posts: 81
Joined: Wed Sep 18, 2019 12:21 am

Re: Molecular to Empirical Formula

Postby Sofia Barker 2C » Wed Oct 09, 2019 10:47 am

You cannot solve for the molecular formula knowing only the empirical formula unless the problem provides the molar mass of the molecular formula. If this value is not provided, then you cannot solve for the molecular formula. If the value is provided, then compare it to the molar mass of the empirical formula by dividing one over the other. This gives their ratio and thus tells you whether your empirical formula is, in fact, the molecular formula or whether you need to multiply the subscripts of the empirical formula by the ratio to get the actual molecular formula.

Grecia Velasco 4D
Posts: 56
Joined: Thu Jul 11, 2019 12:17 am

Re: Molecular to Empirical Formula

Postby Grecia Velasco 4D » Wed Oct 09, 2019 12:15 pm

Calculate the empirical formula's molar mass. You should be given the molecular formulas molar mass. To find the molecular formula = Molecular formula molar mass/ empirical formula molar mass= #. Use this # and multiply it with the empirical formula, this gives you the molecular formula.

AChoudhry_1L
Posts: 55
Joined: Sat Sep 07, 2019 12:17 am

Re: Molecular to Empirical Formula

Postby AChoudhry_1L » Wed Oct 16, 2019 6:33 pm

You would only be able to do this if the problem provides the molar mass of the molecular formula. This mass is usually provided in problems if they want you to find the molecular formula. You would then divide the given molar mass by the mass of the empirical formula mass. The answer you get is what you should multiply the empirical formula by to get the molecular formula.

TimVintsDis4L
Posts: 81
Joined: Sat Aug 17, 2019 12:17 am

Re: Molecular to Empirical Formula

Postby TimVintsDis4L » Sat Oct 19, 2019 7:44 pm

The Empirical formula is needed to calculate the molecular formula but cannot be done so without the molar mass. Once you have the molar masses of both the Empirical formula and the Molecular formula you divide the two to get the ration. If E(molar mass)/M(molar mass)= 2, then multiply the Empirical formula by 2 to get the molecular formula.

Rebekah Alfred 1J
Posts: 82
Joined: Thu Jul 11, 2019 12:15 am
Been upvoted: 1 time

Re: Molecular to Empirical Formula

Postby Rebekah Alfred 1J » Sun Oct 20, 2019 10:11 pm

You would only be able to do this if the problem provides the molar mass of the molecular formula. This mass is usually provided in problems if they want you to find the molecular formula. You would then divide the given molar mass by the mass of the empirical formula mass. The answer you get is what you should multiply the empirical formula by to get the molecular formula.
Specifically, you multiply the subscripts of the empirical formula by the answer you get.

Jacob Villar 2C
Posts: 84
Joined: Sat Aug 17, 2019 12:18 am

Re: Molecular to Empirical Formula

Postby Jacob Villar 2C » Sun Oct 20, 2019 10:16 pm

You would have to find the molar mass using the empirical formula, and divide the given molar mass by this value. Then with the answer, which is usually a whole number, multiply all the subscripts of the empirical formula by the molar mass ratio.

Nathan Rothschild_2D
Posts: 106
Joined: Fri Aug 02, 2019 12:15 am

Re: Molecular to Empirical Formula

Postby Nathan Rothschild_2D » Sun Oct 20, 2019 11:38 pm

You can always check your molecular formula if converting from empirical by finding the molar mass of your molecule and making sure it matches with the molar mass given in the equation.

CalvinTNguyen2D
Posts: 82
Joined: Thu Jul 25, 2019 12:16 am

Re: Molecular to Empirical Formula

Postby CalvinTNguyen2D » Sun Oct 20, 2019 11:43 pm

To find the molecular formula, you'll need both the molecular mass and the mass of the empirical formula. Simply divide the molecular mass by the empirical mass, and you'll get the ratio you need to multiply the empirical formula by to find the molecular formula!


Return to “Empirical & Molecular Formulas”

Who is online

Users browsing this forum: No registered users and 1 guest