Earlier, we have discussed on the strategy of Determining the Molecular Formula of Compounds using Composition by Mass.
Today, we will discuss on the Determination of Molecular Formula of Hydrocarbons using Combustion Data. This is a new concept for those that making their transition from GCE O-Levels to GCE A-Levels and thus will be one of the key questions to be asked in GCE A-Level H1 and H2 Chemistry Examinations.
Let’s look at the method involved.
Hydrocarbons burns in excess oxygen based on the following equation:
CxHy (g) + (x + y/4) O2 (g) –> xCO2 (g) + y/2 H2O (l)
At room temperature conditions or s.t.pm the water product is actually a liquid. Thus, the volume is negligible compared to volumes of CxHy (g), O2 (g) and CO2 (g).
Using Volume Ratio;
Hence, if 1cm3 of is completely burned in oxygen,
Volume of oyxgen used = (x + y/4) cm3
Volume of carbon dioxide produced = x cm3
Volume of water produced (as liquid) = 0 cm3
Let’s check out an exam-based question to see how we can make use … Continue reading ...