Separating crude oil using fractional distillation
Crude oil is heated until it turns into a gas . The gases enter a fractionating column. A fractionating column has a temperature gradient. It is hot at the bottom and cold at the top. The large hydrocarbon have high boiling point, so they turn into liquids early on drain out near the bottom of the column . The small hydrocarbons have low boiling point so they turn back into liquids early near the top of the column , where it's cooler. This separates the oil out into fractions . Each fraction contains a mixture of hydrocarbons with similar boiling points.
How limewater is used to test for CO2 .
The gas is bubbled through the limewater. If carbon dioxide is present it reacts with calcium hydroxide in limewater to produce calcium carbonate . This turns the limewater cloudy.
The hydrocarbon is heated until it vaporises. The vapour is passed over a catalyst . This cracks the hydrocarbons into small alkanes and alkanes.