Fractional distillation of crude oil
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What is crude oil?
Crude oil is a mixture of mostly alkanes, both branched and unbranched
What does crude oil contain besides hydrocarbons?
Crude oil contains small amounts of other compounds, like sulfur containing compounds
How do sulfur compounds in crude oil contribute to pollution?
When burnt, sulfur compounds produce sulfur dioxide
How is sulfur trioxide formed in the atmosphere?
Sulfur dioxide reacts with oxygen high in the atmosphere to form sulfur trioxide
What happens when sulfur trioxide reacts with water in the atmosphere?
Sulfur trioxide reacts with water to form sulfuric acid
What environmental issue is cause by the formation of sulfuric acid from sulfur compounds in crude oil?
The formation of sulfuric acids contributes to acid rain
What is the process called that separates crude oil into useful products?
Fractional distillation
What does each fraction consist of?
A mixture of hydrocarbons with similar chain lengths and properties
Where do short chain hydrocarbons condense in the fractionating tower, and why?
Near the top of the tower, where it is cooler, because they have lower boiling points
What is the thick residue that collects at the base of the tower called?
Tar or bitumen
What is tar/bitumen used for? What happens when supply exceeds demand?
It is used for road surfacing, but when supply exceeds demand, it is further processed to produce more valuable products
What is the full process of fractional distillation using the fractionating tower? • X heated in …. • Mixture = tower • Up, trays, caps, cool enough • Vapour = liquid, piped off • Short chains = top, cooler • Thick substance left
• Crude oil is heated in furnace • A mixture of liquid and vapour passes into the tower, • Vapour then passes up the tower through a series of trays containing bubble caps until they arrive at a tray that is sufficiently cooled • Vapour then condenses into a liquid which is piped off each tray • Shorter chain hydrocarbons condense in trays nearer to top of the tower, where it is cooler • A thick residue is left at the base of the tower call tar, used for road surfacing
Why do shorter chain hydrocarbons condense in trays nearer to the top of the tower?
This is because they have lower boiling points
What type of process is fractional distillation?
It is a physical process
What type of intermolecular forces are broken during vaporisation in fractional distillation?
Van der Waals forces between the molecules are broken during vaporisation
What happens to the van der Waals forces during condensation in fractional distillation?
Van der Waals forces reform between the molecules during condensation
What is fractional distillation, and how is it different from distillation?
Fractional distillation separates a mixture of several components with different ranges of boiling temperatures whereas distillation separates all the volatile components off a mixture from the non - volatile ones