- Process:
-find CO2 and H2O (mole)
-find C and H
-C:H
-CxHx
-check the answer
-if the totals don't balance, there is another element in the compound (usually O or N)
-difference of totals = mass of the other element
-CxHx or CxHxUx
- Example
An organic compound weighed 99.99 g was burnt and in the product there is 191.29 g carbon dioxide and 117.36 g water. (there IS the element O in the compound)
- CO2: 191.29 g x 1 mol / 44.0 g = 4.3475 mol
H2O: 117.36 g x 1 mol / 18.0 g = 6.52 mol
- C: 4.3475 mol
H: 13.04 mol
- C:H = 1:2.999424957 = 1:3
- Check: C: 4.3475 mol x 12.0 g / 1 mol = 52.17 g
H: 13.04 mol x 1.0 g / 1 mol = 13.04 g
52.17 g + 13.04 g = 65.21 g < 99.99 g
- O: 99.99 g - 65.21 g = 34.78 g
34.78 g x 1 mol / 16.0 g = 2.17375 mol
- C:H:O = 1:2.999424957:2.17375 = 1:3:2.17375 = 2:6:1
- C2H6O
