Organic Chemistry (Alkanes, Alkenes, Crude Oil) Flashcards
Explain why all of these compounds are described as hydrocarbons (2)
The compounds all contain hydrogen and carbon atoms only
Why are B and E described as unsaturated? (1)
Compounds B and E have double bonds
Which letter represents the first member of the homologous series of alkanes? (1)
A
Which letter represents the compounds that have the empirical formula CH2? (1)
B, E, F
Why does F not decolourise bromine water? (1)
Compound F has no double bonds, but only has single bonds therefore is saturated and does not decolourise bromine water.
Identify which of these fractions has the darkest colour (1)
- fuel oil
- gasoline
- kerosene
Fuel oil
Identify which of these fractions has the highest boiling point (1)
- fuel oil
- gasoline
- kerosene
Fuel oil
Identify which of these fractions contains molecules with the fewest carbon atoms (1)
- fuel oil
- gasoline
- kerosene
Gasoline
Name a catalyst used in industry for cracking. (1)
Alumina
One reaction that occurs in cracking involves the conversion of one molecule of hexadecane into one molecule of octane and two molecules of an alkene. Complete the equation for this reaction (2)
C16H34 –> C8H18 + ___
C16H34 –> C8H18 + C4H8 + C4H8
Give three reasons why cracking is carried out. (3)
There is a greater supply of long-chain hydrocarbon molecules, and there is a higher demand for short-chain hydrocarbons than long-chain hydrocarbons Therefore, cracking is carried out where alkenes are used to make polymers.
One of the compounds sometimes present in crude oil has the formula C6H12S. Explain why it is important to remove this compound from a fuel (2)
When burned, this compound will form sulfur dioxide which can cause environmental problems like acid rain
Which fraction has the lowest boiling point? (1)
Refinery gases
Which fraction is the most viscous? (1)
Bitumen
Some fractions containing long-chain hydrocarbons are cracked. The cracking of octadecane (C18H38) produces octane (C8H18) and one other product. Write a chemical equation for this cracking reaction. (1)
C18H38 –> C8H18 + C10H20
Explain why it is important to crack long-chain hydrocarbon fractions (2)
There is a high supply of long chain hydrocarbons and a high demand for short chain hydrocarbons. Therefore the alkenes produced can be used to make polymers
Write a chemical equation for this incomplete combustion of octane. (2)
C818 + 8 1/2O2
–> 8CO + 9H2O
What is the name of this type of reaction? (1)
Addition
Which of these is a correct description of a monomer? (1) A molecule used to make a polymer B a molecule with only single bonds C an atom in a polymer D a repeat unit in a polymer
A molecule used to make a polymer.
State the name of this compound (1)
Propene
State the meaning of the term biodegrade. (2)
Polymers are broken down by bacteria.
What property of these polymers prevents them from biodegrading? (1)
They are unreactive or inert
Explain what is meant by the term isomerism (2)
Molecules with the same molecular formula but different structural and displayed formula.
State the type of reaction and give the colour of the bromine water before and after the reaction with heptene. (3)
Type of reaction:
Colour before:
Colour after:
Type of reaction: Addition
Colour before: Orange
Colour after: Colourless
Explain, in terms of the bonds, why heptane is described as saturated and heptene as unsaturated. (2)
Heptane is saturated as all of its bonds are single bonds. And Heptene is unsaturated as it contains double bonds.
State the name of this organic product. (1)
Bromomethane.
State the condition used in this reaction (1)
Sunlight
What term is used for this type of reaction (1)
Substitution
Explain why a different product is formed in reaction 2 and why this product is dangerous. (3)
In reaction 2, incomplete combustion occurs. This is dangerous as it is toxic and reduces the capacity of the blood to carry oxygen.
