Formula steps

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Maldonado3K
Posts: 39
Joined: Fri Sep 29, 2017 7:07 am

Formula steps

Postby Maldonado3K » Sun Apr 08, 2018 11:50 pm

Does anyone have any tricks to remembering the steps to find the empirical formula vs the molecular formula?

Christina Inchuachan 1C
Posts: 7
Joined: Wed Nov 15, 2017 3:04 am

Re: Formula steps

Postby Christina Inchuachan 1C » Mon Apr 09, 2018 1:42 am

I think the steps to finding the empirical formula and molecular formula are the same. You would need the empirical formula to find the molecular formula. You would have to divide the gram molecular mass by the empirical formula mass. Then, multiply each of the subscripts within the empirical formula by the previous quotient.

304984981
Posts: 28
Joined: Fri Apr 06, 2018 11:05 am

Re: Formula steps

Postby 304984981 » Tue Apr 10, 2018 11:41 am

pretty easy
always remember this equation: known molar mass/molar mass from empirical formula

YeseniaGomez_1L
Posts: 32
Joined: Fri Apr 06, 2018 11:02 am
Been upvoted: 1 time

Re: Formula steps

Postby YeseniaGomez_1L » Tue Apr 10, 2018 8:53 pm

I think it is easier to learn it as one process, either you can find the molecular formula using the empirical or the other way around. Finding the molecular formula first seems like a shorter process to me. First you multiply the given total mass by the percents of composition given, the mass you get from this you convert to moles using the atom weight. Using these mole values you can write out the molecular formula, then simply it to the empirical formula. Hope this helps, if it doesn't really make sense there is a good khan academy video on this.

Vienna Cimetta 1L
Posts: 31
Joined: Thu Feb 01, 2018 3:01 am

Re: Formula steps

Postby Vienna Cimetta 1L » Fri Apr 13, 2018 12:41 am

To find the empirical formula you first have to find the mass composition of each element, then find the moles of each element, and divide the moles of each element by the element with the smallest number of moles. If needed, round these values found to the nearest whole number to get the molar ratios. Then, to find the molecular formula find the molar mass of your empirical formula and divide that value by the molar mass of the entire compound (this should be given in the question). This will give you another ratio that will tell you whether you need to multiple the subscript of your empirical formula to find the molecular formula.


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