C9 Flashcards

1
Q

What is crude oil

A

Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud

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2
Q

What is the composition of crude oil

A

Cirde oil is a mixture of a very large number of compounds. Most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only

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3
Q

What is a hydrocarbon

A

A chemical compound made up of hydrogen and carbon atoms only

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4
Q

What is the general formula for alkanes

A

C(n) H(2n+2)

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5
Q

What are the first 4 members of the alkanes

A

Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10

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6
Q

How is crude oil seperated

A

Fractional distillation

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7
Q

Give examples of the uses of the fractions derived from seperating crude oil

A

Petrol, kerosene, diesel oil, heavy fuel oil, liquified petroleum gas

It can also be used as feedstock such as solvents, lubricants, polymers, detergents.

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8
Q

How does size of the hydrocarbon effect: boiling point, viscosity and flammability

A
Short chain
Lower BP
Low viscosity
Higher flammability
Long chain
Higher boiling point
High viscosity
Lower flammability ( burns with smokier flame )
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9
Q

How does fractional distillation work

A

Crude oil is heated until most has turned to gas
Gases enter fractionating column and liquids drained off
(There is a temperature graduent in the column (hotter at the bottom and cooler at the top)) -CB
Gases rise and as they rise the temperature cools
Once the gases reach a fraction cool enough, they condense and are drained off
The longer chains condense lower down, shortest chain stay as gases

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10
Q

General formula for the complete combustion of hydrocarbons

A

Hydrocarbon + oxygen = carbon dioxide + water

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11
Q

What is cracking?

A

Longer, less useful hydrocarbons can be split up to form shorter hydrocarbons which are more useful for fuel, it also produces alkenes

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12
Q

What are the methods for cracking

A

Catalytic cracking:
Vaporise hydrocarbons are passed over a hot powdered aluminium oxide catalyst. The longer chains are split apart on the surface of the catalyst
Steam cracking:
Vaporised hydrocarbons are mixed with steam and heated to high temperature to crack them

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13
Q

Shat are the products of cracking

A

Shorter alkanes

Alkenes

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14
Q

What is the test for an alkene

A

They react with bromine water and turn it from yellow to colourless

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15
Q

Why do we crack hydrocarbons

A

There is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels
Alkenes are used to produce polymers and starting materials for the production of many other chemicals

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16
Q

What are alkenes

A

Alkenes are hydrocarbons with a double carbon- carbon bond

17
Q

What is the general formula for an alkene

A

CnH2n

18
Q

What are alkenes unsaturated

A

Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms

19
Q

What are the first 4 alkene members

A

Ethene C2H4
Propene C3H6
Butene C4H8
Pentene C5H10

20
Q

Give the formula for incomplete combustion of hydrocarbons

A

Hydrocarbon + oxygen ( incomplete amount ) = water + carbon + carbon monoxide