Homework Problem F9

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Jessica Urzua-1H
Posts: 37
Joined: Tue Nov 14, 2017 3:01 am

Homework Problem F9

Postby Jessica Urzua-1H » Sat Apr 07, 2018 11:11 pm

The homework problem F9 asks: In what atom ratios are the atoms present in vanillin? I am pretty sure that the problem is asking for the empirical formula, but I just wanted to make sure. Any clarification would be helpful.

Alma Flores 1D
Posts: 64
Joined: Wed Nov 08, 2017 3:01 am

Re: Homework Problem F9

Postby Alma Flores 1D » Sun Apr 08, 2018 12:24 am

Yes, the ratio between atoms in a molecule is the empirical formula.

Jimmy lira-1G
Posts: 61
Joined: Fri Apr 06, 2018 11:03 am

Re: Homework Problem F9

Postby Jimmy lira-1G » Sun Apr 08, 2018 11:45 am

Yes, it is asking to find the empirical formula from the mass percentages of Vanillin. They give you mass percentages of 63.15% C, 5.30% H, and 31.55% O. The mass percentage of each element X, m(X), in exactly 100g of the compound is equal to its mass percentage in grams; so 63.15% is 63.15g and so forth. After finding the mass of each element then convert each mass to an amount of atoms in moles by using the molar mass of each element given. Then divide each amount you received by the smallest mol amount you have. Then you have to make sure the compound has whole numbers of atoms , so if it doesn't you would multiply across by the reciprocal of the fraction of atoms that you have and you will receive whole numbers for each element giving you the empirical formula.

- Finding the mass in moles
for carbon
ex- 63.15g/ 12.01g*(molc)^-1 ; you would do the same for each element

-Jimmy Lira , section 1G, Hope that helps !


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