empirical to molecular formula [ENDORSED]

dtolentino1E
Posts: 101
Joined: Thu Jul 11, 2019 12:17 am

empirical to molecular formula

hi!

so when you are trying to calculate the molecular formula and you are given the empirical formula and the mass of whatever compound, i know that you're supposed to calculate the molar mass from the empirical formula and find a ratio between the masses, then multiply by whatever number it comes out to be.

can someone tell me which mass (molar or the given one in the equation) is divided by the other?

Rida Ismail 2E
Posts: 139
Joined: Sat Sep 07, 2019 12:16 am

Re: empirical to molecular formula

Ok, so your question confuses me just a bit. But I want to give you a list of steps which should hopefully answer your question.

If the question gives you an empirical formula or you just calculated the empirical formula, you would then need to calculate the empirical formula of the empirical formula. The question needs to give you the molar mass of the molecular formula. From the molar mass of the molecular formula, you can find out the ratio of atoms in the empirical vs the molecular by the empirical molar mass divided by the molecular molar mass. This will give you the ratio and you can multiple each atom in the empirical formula by this number.

Sam McNeill 1E
Posts: 110
Joined: Sat Aug 24, 2019 12:17 am

Re: empirical to molecular formula  [ENDORSED]

The molecular formula molar mass is divided by the empirical's, and then you multiply the empirical's subscripts by whatever the quotient is.

LNgo 1G
Posts: 100
Joined: Sat Aug 24, 2019 12:16 am

Re: empirical to molecular formula

You divide the given molar mass by the empirical mass. The empirical mass will always be smaller than the molecular mass because it is the smallest ratio of the atoms so you can try to remember that you divide by the smaller number.

Kallista McCarty 1C
Posts: 212
Joined: Wed Sep 18, 2019 12:18 am

Re: empirical to molecular formula

You divide the given molar mass of the molecular formula by the calculated molar mass of the empirical formula that you found!

Nathan Nakaguchi 1G
Posts: 102
Joined: Wed Sep 18, 2019 12:22 am
Been upvoted: 1 time

Re: empirical to molecular formula

I believe it goes: (Molar Mass Given)/(Empirical molar mass)= Number you need to multiply the empirical formula to get the molecular formula.

britthanul234
Posts: 51
Joined: Wed Sep 18, 2019 12:21 am

Re: empirical to molecular formula

You simply divide the molar mass by the empirical mass.

Kelsey Ash 1D
Posts: 50
Joined: Wed Sep 18, 2019 12:16 am

Re: empirical to molecular formula

You divide the given molar mass (the mass of the molecular formula) by the molar mass of the empirical formula. Whatever the product of that equation is is the number you multiply the empirical formula by.

Chem_Mod
Posts: 18400
Joined: Thu Aug 04, 2011 1:53 pm
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Re: empirical to molecular formula

LNgo 14A wrote:You divide the given molar mass by the empirical mass. The empirical mass will always be smaller than the molecular mass because it is the smallest ratio of the atoms so you can try to remember that you divide by the smaller number.

Remember that in some cases the molecular formula and the empirical formula are the same. In that situation, both masses would be equal.

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

Re: empirical to molecular formula

When finding the ratio, divide the total molar mass by the empirical mass. Sometimes, this will give you 1 and that means that the molar mass is the same as the empirical mass and therefore, the formulas are the same as well.