4 - Organic chemistry (b) Crude oil
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What is crude oil?
A mixture of hydrocarbons.
How is crude oil separated? How does this work?
Crude oil is separated using fractional distillation. This separates them according to boiling point, as this is the point in the fractionating column they will come out of because the column is heated.
What are the main fractions obtained from crude oil?
Refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen.
What is the trend in colour, boiling point and viscosity of refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen?
Colour gets darker as you go down the list. Boiling point and viscosity increase as you go down the list. refinery gases gasoline kerosene diesel fuel oil bitumen
What is released when fuel is burned?
Heat energy
What are the products of complete and incomplete combustion of hydrogen with oxygen from the air?
Complete = Carbon Dioxide and Water Incomplete = Carbon Monoxide, Water and Soot
Why is carbon monoxide poisonous?
It binds to haemoglobin in red blood cells, which prevents oxygen from binding to the haemoglobin and transporting oxygen to the body’s cells and tissues.
In car engines, the temperature reaches high enough for what?
For nitrogen and oxygen from the air to react, forming oxides of nitrogen.
How can the combustion of some impurities in hydrocarbon fuels produce sulfur dioxide?
The sulfur atoms contained as an impurity in hydrocarbons are oxidised by the oxygen in the air, forming sulfur dioxide.
How do sulfur dioxides and oxides of nitrogen form acid rain?
Sulfur dioxides react with water in the raindrops to form sulfuric acid, which can harm the environment. Oxides of nitrogen react with water in the raindrops to form nitric acid, which can harm the environment.
How are long-chain alkanes converted to alkenes or shorter chain alkenes?
By using cracking, which uses silica or alumina catalyst at a temperature range of 600-700⁰C.
Why is cracking necessary?
Because there is high demand for shorter chain hydrocarbons, but less supply, meaning cracking can convert less wanted and valuable long chain hydrocarbons into shorter chain ones to meet demand.