Steps to calculating Molecular Formulas

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nataliefgarcia3I
Posts: 22
Joined: Fri Sep 28, 2018 12:24 am

Steps to calculating Molecular Formulas

Postby nataliefgarcia3I » Sat Oct 06, 2018 7:43 pm

Defintion: A molecular formula is the exact chemical formula of a compound.

Steps:
1.Figure out the empirical formula of the compound.
-If the problem and information given provides percentages, convert it into grams.
- Convert the grams into moles
- Divide each number by the smallest number of moles.
-Write the empirical formula
2. Find the molar mass of the empirical formula
3.Divide the Molecular Formula Molar Mass by the Empirical Formula Molar Mass
4. Multiply the whole number to the subscripts of the empirical formula

Caitlin_Murphy_3C
Posts: 36
Joined: Fri Sep 28, 2018 12:23 am

Re: Steps to calculating Molecular Formulas

Postby Caitlin_Murphy_3C » Sun Oct 07, 2018 2:48 am

When finding the empirical formula, after dividing each number by the smallest number of moles, how close do the new values need to be to a whole number to just round up/down? Vs multiplying each value by a certain integer to get it closer to a whole number?
Thanks!

Samantha Hoegl Roy 2C
Posts: 81
Joined: Fri Sep 28, 2018 12:15 am

Re: Steps to calculating Molecular Formulas

Postby Samantha Hoegl Roy 2C » Sun Oct 07, 2018 4:27 pm

Our TA said to just go with "your feeling"; like 3.9 is close enough, but 3.8 logically not. I would just always do the step, where you divide the numbers by the smallest one to be sure

Alli Hinmon 3E
Posts: 30
Joined: Wed Nov 08, 2017 3:00 am

Re: Steps to calculating Molecular Formulas

Postby Alli Hinmon 3E » Sun Oct 07, 2018 4:53 pm

The first video on Audio-Visual Focus-Topics, Assessments & Surveys really helped me with how to calculate empirical and molecular functions!


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