Calculating Emperical Formula of an Organic Compound

So in last class we learned how to find both Emperical and Molecular formulas. Today we learned how to found the EF of an organic compound, which is some what harder.

Basically, we can find the EF of any organic compund by burning the compund (collecting/weighing product). We then have a burnt product. We then can calculate the moles of each element from the original organic (unburnt) product.

Now let's try an example to see if we can calculate it right.

EX. What is the EF of a compound that when a 15.00 gram sample is burned it produces 25.0 grams of CO2 and 10.0 grams of H20

Step 1: Calculate all moles of CO2 and H2O

25.0 CO2 x 1mol CO2/ 44.0g CO2 = 0.568 mol CO2
10.0 H2O x 1mol H2O/18.0 H2O = 0.556 mol H2O

Step 2: Find moles of C and moles of H in CO2 and H2O

0.568 mol CO2 x 1molC/1 molCO2 = 0.568 mol
0.556 mol H2O x 2molH/1molH20 = 1.112 mol

Step: 3: Divide both moles by smallest molar amount

C = 0.568/0.568 = 1
H = 1.112/0.568 = 2

There for the Emperical Formula is CH₂

Step 4: Check answer.
Convert moles back into grams. The result should be 15.0g. If the answer does not match, that means Oxygen is a component. To find the amount of Oxygen use this formula.

Mass of O = Mass of compound - mass of C - mass of H


This concludes my blog. Have a good night everyone.






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