Thursday, December 2, 2010

Empirical and Molecular Formula

The Empirical Formula gives the lowest term ration of atoms/ moles in the formula
**all ionic compounds are given in the empirical formula


Ex. C8H12-------> C2H3
     Molecular to empirical
General case of converting grams of substances to empirical formula:
As we have already learned to do convert from grams to moles for each measurement, by divide it by it's atomic mass.
Then dived each molar amount by the smallest molar amount to receive a ration. Round these ratios to whole numbers and the make them your subscripts of your equation.
An example is provided in the video below.

General Case of converting percentage ratios into empirical formula:
Assume you have 100g of the substance. Convert each percentage into grams. Divide the amounts by their atomic mass. It will give you the ratio's which you'll need to round off and then use as your subscripts.



Molecular Formula: Is a multiple of the empirical formula which shows the actual number of atoms that form  each specific compound

Molar Mass / Molar Mass of empirical formula = Molecular Formula

Examples are in the video below!



This video does a far better job of explaining than I ever could so please actually watch it! It's worth it trust me!

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