Hydrocarbons And Crude Oil

Question 1

What is organic chemistry

Answer 1

The chemistry of carbon compounds

Question 2

General formula of alkanes

Answer 2

CnH2n+2

Question 3

What is the general formula of alkenes

Answer 3

CnH2n

Question 4

What is displayed formulae

Answer 4

The special arrangement of all the atoms and bonds in a molecule

Question 5

What is molecular formulae

Answer 5

The actual number of each atom in a molecule one at a time eg C2H6

Question 6

What is structural formulae

Answer 6

Similar to displayed formula not all bonds are shown although all atoms are still indicated using subscript numbers

Question 7

What is a homologous series

Answer 7

a series of organic compounds that have similar features and chemical properties due to them having the same functional group.

Question 8

First four alkenes

Answer 8

Methane Mice
Ethane Eat
Propane Paper
Butane Bags

Question 9

What is a hydrocarbon

Answer 9

A compound made up of only carbon and hydrogen atoms

Question 10

How is crude oil formed

Answer 10

Crude oil is formed over millions of years from the effects of high pressures and temperatures on the remains of biomass (plant and animals) mainly plankton that was buried in mud

Question 11

What is a saturated hydrocarbon and give an example

Answer 11

A hydrocarbon with only single bonds between its atoms. This means that it contains as many hydrogen atoms as possible in each molecule eg an alkane

Question 12

What is an unsaturated hydrocarbon and give a example

Answer 12

A hydrocarbon whose molecules contain at least one carbon-atom double bond eg. An alkene

Question 13

Describe the process of fractional distillation

Answer 13

The crude oil is heated until vaporised, these vapours move up the fractioning column the further up the column the cooler it becomes. As the gasses move up the fractioning column they cool down, as each fraction condenses at a different temperature they are collected at different points, each fraction contains hydrocarbons with a similar number of carbon atoms. The refinery gasses have very low boiling points and do not condense and pass out the top of the fractioning column, longer chained hydrocarbons such as bitumen have higher boiling points and collected towards the bottom of the column whereas shorter chained hydrocarbons like petrol are collected near the top.

Question 14

Give 5 examples of products obtained from crude oil

Answer 14

Polymers, lubricants, Solvents, detergents and adhesives

Question 15

What is liquified petroleum gas used for

Answer 15

Domestic heating & cooking

Question 16

What is petrol used for

Answer 16

Fuel for cars

Question 17

What is kerosene for

Answer 17

Jet fuel

Question 18

What is diesel for

Answer 18

Powering diesel engines

Question 19

what is heavy fuel oil for

Answer 19

Ships & power stations

Question 20

What is bitumen used for

Answer 20

Surfacing roads and roofs

Question 21

What is the order of fractions in the column ascending

Answer 21

Bitumen, fuel oil, diesel, kerosene (paraffin), petrol (gasoline) , refinery gases

Question 22

How does boiling point correspond with the size of their molecules

Answer 22

the intermolecular forces of attraction between large molecules becomes greater as there are more electrons in the molecules and greater surface area contact between them meaning that more heat is needed to separate the molecules, hence with increasing molecular size there is an increase in boiling point

Question 23

What is viscosity

Answer 23

The ease of flow of a liquid, high viscosity liquids are thick and flow less easily

Question 24

How does viscosity correspond to chain length

Answer 24

Viscosity increases with increasing chain length, due to the increased intermolecular forces of attraction as molecular size increases

Question 25

How does flammability correspond to chain length

Answer 25

smaller hydrocarbon molecules are more flammable and are easier to ignite than larger molecules

Question 26

Equation for complete combustion

Answer 26

Hydrocarbons + oxygen —> carbon dioxide+ water

Question 27

Equation for incomplete combustion

Answer 27

Hydrocarbon + oxygen —> carbon monoxide + carbon + water

Question 28

Equation for incomplete combustion when there is not enough oxygen to form monoxide

Answer 28

Hydrocarbon + oxygen —> carbon + water

Question 29

What are the 2 methods used for cracking alkanes

Answer 29

Catalytic cracking and steam cracking

Question 30

Describe the process for cracking

Answer 30

The hydrocarbon is heated until vapourised/ evaporated, the broken porcelain or aluminium oxide acts as a catalyst, as the vapours pass over the catalyst thermal decomposition occurs and hydrocarbon is cracked into smaller chained hydrocarbons and an alkane and an alkene are produced

Question 31

Why are alkenes more desirable than alkanes

Answer 31

They are more reactive because due to the presence of carbon carbon double bond so they can take part in reactions alkanes can’t

Question 32

What 2 useful reactions do alkenes undergo

Answer 32

Bromination and polymerisation

Question 33

What is the test for alkanes/alkenes

Answer 33

Bromine water
Alkane + bromine water=no reaction & solution stays orange
Alkene + bromine water=reaction & solution turns colourless