organic chemistry Flashcards

1
Q

What is crude oil?

A

Crude oil is a finite resource found in rocks formed over millions of years from the remains of ancient biomass (mainly plankton buried in mud). It is a mixture of a very large number of compounds, most of which are hydrocarbons, most being alkanes. The hydrocarbons each have a different boiling point.

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2
Q

What are hydrocarbons?

A

Hydrocarbons are molecules made up of hydrogen and carbon atoms only.

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3
Q

What are alkanes?

A

Alkanes are a hydrocarbon with general formula CnH2n+2.

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4
Q

Give the molecular formula and name when there is an alkane and n=1.

A

methane - CH4

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5
Q

Give the molecular formula and name when there is an alkane and n=2.

A

ethane - C2H6

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6
Q

Give the molecular formula and name when there is an alkane and n=3.

A

propane - C3H8

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7
Q

Give the molecular formula and name when there is an alkane and n=4.

A

butane - C4H10

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8
Q

Are alkanes saturated or unsaturated molecules? Why?

A

Alkanes are saturated molecules as the carbon atoms are fully bonded to hydrogen atoms.

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9
Q

As the size of the alkane increases, what happens to the viscosity?

A

As the size of the alkane increases, the molecules become more viscous.

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10
Q

What does viscosity mean?

A

Viscosity means the thickness of a fluid.

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11
Q

As the size of the alkane increases, what happens to the flammability?

A

As the size of the alkane increases, the molecules become less flammable.

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12
Q

As the size of the alkane increases, what happens to the boiling points?

A

As the size of the alkane increases, the boiling points increase. (methane –> butane are gases at room temperature)

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13
Q

What three things run on hydrocarbon fuels?

A

Ships, planes and cars run on hydrocarbon fuels.

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14
Q

What is complete combustion?

A

Hydrocarbon fuels release energy when they are combusted. During combustion, the carbon and hydrogen atoms react with oxygen (oxidised). If the oxygen is unlimited, the reaction produces CO2 and H2O, which is complete combustion.

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15
Q

Give the complete combustion of methane.

A

complete combustion of methane:
methane + oxygen –> carbon dioxide + water
CH4 + 2O2 –> CO2 + 2H20

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16
Q

What needs to happen for the hydrocarbons in crude oil to be useful?

A

In order or the hydrocarbons in crude oil to be useful, we have to separate them by fractional distillation.

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17
Q

Describe the process of fractional distillation in terms of crude oil.

A

fractional distillation of crude oil:

  • crude oil is separated into fractions, each containing hydrocarbons with a similar number of carbon atoms
  • the crude oil is heated to a very high temperature, causing it to boil
  • all of the hydrocarbons turn into a gas
  • they condense when they reach their boiling point and are removed
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18
Q

In the fractional distillation of crude oil, when are long chain hydrocarbons removed?

A

Very long chain hydrocarbons have very high melting points, so they are removed near the bottom of the column.

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19
Q

In the fractional distillation of crude oil, when are short chain hydrocarbons removed?

A

Very short chain hydrocarbons have very low boiling points, so they are removed near the top of the column as a gas as they don’t condense.

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20
Q

Give five products of the fractional distillation of crude oil and what they’re used for.

A

products of crude oil:

  • petrol and diesel are used in cars
  • kerosene is used as jet fuel
  • heavy fuel oil is used in ships
  • liquefied petroleum gas (LPG) is used in camping stoves
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21
Q

Give five products of the fractional distillation of crude oil and rate the boiling points from highest to lowest.

A
products of crude oil boiling points:
HIGHEST
heavy fuel oil
petrol
kerosene
diesel
liquefied petroleum gas (LPG)
LOWEST
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22
Q

What is LPG?

A

LPG is liquefied petroleum gas, a product of the fractional distillation of crude oil and has a very low boiling point. It contains mostly propane and butane.

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23
Q

What can some fractions from the fractional distillation of crude oil be used to make?

A

Some fractions are used as feedstock (a chemical used to make other chemicals) for the petrochemical industry. It can be used to make solvents, lubricants, detergents and polymers.

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24
Q

What is cracking?

A

Cracking is when a large alkane is broken down (cracked) into smaller, more useful molecules.

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25
Q

What are the products of cracking?

A

products of cracking:

  • shorter chain alkanes are used in fuels
  • alkenes (another kind of hydrocarbon)
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26
Q

What are the two kinds of cracking?

A

types of cracking:

  • catalytic cracking - use heat and a catalyst, which both speed up the reaction
  • steam cracking - use heat and steam
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27
Q

What is an alkene?

A

An alkene is a hydrocarbon that has at least one carbon to carbon double bond. They have general formula CnH2n.

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28
Q

Are alkene molecules saturated or unsaturated? Why?

A

Alkene molecules are unsaturated as the alkenes have fewer hydrogen atoms than the alkane with the same number of carbon atoms.

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29
Q

Which is more reactive: alkenes or alkanes?

A

Alkenes are more reactive than alkanes.

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30
Q

Why are alkenes useful?

A

Alkenes are useful as they can be used to make polymers and other chemicals.

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31
Q

What is the test for alkenes and alkanes?

A

test for alkenes:
- add bromine water, shake it, the solution will turn colourless

test for alkanes:
- add bromine water, shake it, the solution will remain the same colour

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32
Q

Give the molecular formula and name when there is an alkene and n=2.

A

ethene - C2H4

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33
Q

Give the molecular formula and name when there is an alkene and n=3.

A

propene - C3H6

34
Q

Give the molecular formula and name when there is an alkene and n=4.

A

butene - C4H8

35
Q

Give the molecular formula and name when there is an alkene and n=5.

A

pentene - C5H10

36
Q

What is a displayed formula?

A

The displayed formula shows all of the atoms and covalent bonds.

37
Q

What is the functional group?

A

The functional group is the part of the molecule that determines how it reacts.
eg. the double carbon bond in alkenes

38
Q

What is a homologous series?

A

The members of a homologous series all have the same functional group.

39
Q

What happens when alkenes are combusted?

A

combustion of alkenes:

  • they produce CO2 and H2O, like alkanes
  • also produce unburnt carbon particles due to incomplete combustion, and because of this, they burn in air with a smoky flame
40
Q

What happens when alkenes undergo hydrogenation?

A

hydrogenation:

  • this is reacting alkenes with hydrogen
  • the two hydrogen atoms are added across the double bond, so the double carbon-carbon bond is now a single bond, so it is now an alkane
41
Q

What is required for the hydrogenation of ethene?

A

For the hydrogenation of ethene, it requires 150 degrees Celsius and a nickel catalyst. This reaction will form ethane.

42
Q

What is required for the hydration of alkenes?

A

for the hydration of alkenes:

  • the water must be steam
  • the temperature must be around 300 degrees Celsius
  • the pressure must be around 70 atmospheric pressure
  • phosphoric acid used as a catalyst.
43
Q

What happens when alkenes are hydrated?

A

hydration of alkenes:

  • this means reacting with water (steam)
  • the reaction is reversible, so any unreacted alkene and steam are passed back through the catalyst
  • it forms an alcohol, which breaks the double carbon-carbon bond and is added across it
44
Q

What happens when alkenes react with halogens?

A

alkenes with halogens:

  • rapid reaction, so no conditions required
  • all add across the double carbon-carbon bond and break it
45
Q

What is the functional group of alcohols?

A

Alcohols are a homologous group with functional group -OH. (They are an alkane with one -H changed to an -OH)

46
Q

Give three uses of alcohols.

A

Uses of alcohols are fuels, solvents and alcoholic drinks.

47
Q

What is a structural formula?

A

The structural formula is written the way that the displayed formula looks, eg. CH3CH2OH for ethanol.

48
Q

Give the structural formula for methanol.

A

Methanol - CH3OH

49
Q

Give the structural formula for ethanol.

A

Ethanol - CH3CH2OH

50
Q

Give the structural formula for propanol.

A

Propanol - CH3CH2CH2OH

51
Q

Give the structural formula for butanol.

A

Butanol - CH3CH2CH2CH2OH

52
Q

How is ethanol made?

A

Ethanol is made by the hydration of ethene. It is one of the most important alcohols.

53
Q

Give the word and symbol equation of the fermentation of sugar.

A

Fermentation of sugar:
Glucose —> ethanol + carbon dioxide
C6H12O6 —> 2C2H5OH + 2CO2

54
Q

What is required for the fermentation of sugar?

A

Requirements for fermentation of sugar:

  • mix sugar solution with yeast, as it converts the sugar to ethanol and CO2
  • the temperature should be 30 degrees Celsius
  • no oxygen (anaerobic conditions)
55
Q

What are the advantages and disadvantages of the fermentation of sugar?

A

Advantages:

  • low temperature doesn’t require a lot of money or energy
  • the sugar comes from plants so it’s renewable

Disadvantages:
- the product is aqueous of ethanol, so we need to purify it by distillation, which requires energy

56
Q

What happens to the solubility of alcohols as the number of carbon atoms increase?

A

As the number of carbon atoms in alcohols increase, the solubility decreases. All alcohols are soluble in water and form neutral solutions.

57
Q

Give the word and symbol equation of when ethanol reacts with sodium.

A

Ethanol + sodium —> sodium ethoxide + hydrogen
C2H5OH + Na —> C2H5ONa + H2

  • always sodium ___oxide (what comes before -anol)
58
Q

Give an example of an oxidising agent.

A

An example of an oxidising agent is acidified potassium dichromate.

59
Q

Give the word and symbol equation of ethanol with an oxidising agent.

A

Ethanol —> ethanoic acid + water
C2H5OH —> CH3COOH + H20
- the arrow represents the oxidising agent
- always ___anoic acid (with what comes before -anol)
- produces a carboxylic acid and water

60
Q

Give the word and symbol equation for the combustion of ethanol.

A

Ethanol + oxygen —> carbon dioxide + water
C2H5OH + 3O2 —> 2CO2 + 3H20
- always releases carbon dioxide and water
- releases energy

61
Q

What is the functional group of a carboxylic acid?

A

The functional group of carboxylic acids is -COOH.

62
Q

Why are carboxylic acids weak acids in water?

A

In water, carboxylic acids are weak acids as the ions CH3COO- and H+ (in terms of ethanolic acid) only partially ionise in aqueous solutions.

63
Q

Give the word and symbol equation for ethanoic acid with a metal carbonate (eg. sodium).

A

Ethanoic acid + sodium carbonate —> sodium ethanoate + carbon dioxide + water
2CH3COOH + Na2CO3 —> 2CH3COONa + CO2 + H2O

  • it makes a salt, CO2 and H2O
64
Q

Give the word and symbol equation for ethanoic acid with ethanol.

A

Ethanoic acid + ethanol (reverse arrow) ethyl ethanoate + water
CH3COOH + C2H5OH (reverse arrow) C4H8O2 + H2O

  • look in book for how to write it lol
  • must be in the presence of sulfuric acid
  • produces an ester and water
  • it is a reversible reaction
65
Q

Why are esters useful?

A

Esters are useful molecules as they often have a pleasant smell, so they are used in foods and perfumes.

66
Q

What is a polymer?

A

A polymer is made by joining thousands of small, identical molecules called monomers.

67
Q

What is an addition polymer?

A

An addition polymer is a polymer where the monomers are alkanes. It is written as poly(name of monomer). The monomers have a double carbon-carbon bond, but the polymer has a single bond.
It is written as (monomer)n, and the bonds reach across the bracket. N represents a large number.

68
Q

What is a condensation polymer?

A

A condensation polymer involves two different monomers with two of the same functional group on each. They are condensation polymers as when the monomers join, they usually lose small molecules like water.

69
Q

What does a box represent in condensation polymers?

A

In condensation polymers, a box represents CH2 going on for a large amount of units.

70
Q

What is ethane diol?

A

Ethane diol - HO-CH2-CH2-OH
Or can be written as OH-box-OH
- contains two of the alcohol group

71
Q

What is hexanedioic acid?

A

Hexanedioic acid - HOOC-CH2-CH2-CH2-CH2-COOH
Or can be written as HOOC-box-COOH
- contains two of the carboxylic acid functional group

72
Q

How do ethane diol and hexanedioic acid react?

A

One molecule of each reacts to form an ester and water. You can continue to add monomers on each end to form a polyester.

  • nHO-box-OH + nHOOC-box-COOH —> (-O-box-O-CO-box-CO-)n + 2nH2O
73
Q

What functional groups do amino acids have?

A

Amino acids contain the functional groups amine (H2N) and carboxylic acid (COOH).

74
Q

Give the structural formula of glycine.

A

Glycine (an amino acid) - H2NCH2COOH

75
Q

What does the reaction of two amino acids form? Why?

A

Two amino acids react to form a condensation polymer because they have two different functional groups.

Eg. Glycine + glycine —> H2NCH2CONHCH2COOH + H2O
Now add another glycine on the end to form a polymer
- nH2NCH2COOH —> (-HNCH2COO-)n + nH2O

76
Q

What is it called when one type of amino acid forms a polymer?

A

A polypeptide is when the polymer is made of one amino acid.

77
Q

What is the name of the product of multiple amino acids forming a polymer?

A

Different amino acids can be combined through condensation polymerisation to form a protein.

78
Q

What does DNA stand for?

A

DNA stands for deoxyribonucleic acid.

79
Q

Why is DNA important?

A

DNA is important as it is a large molecule essential for life in almost all living organisms. It encodes genetic instructions for the development and functioning of all living organisms and viruses.

80
Q

What are most DNA molecules made up of?

A

Most DNA molecules are made up of two polymer chains made from four different monomers called nucleotides, in a double helix.

81
Q

Name three naturally occurring polymers important for life.

A

Naturally occurring polymers important for life:

  • protein (polymer of amino acids)
  • starch (polymer of glucose)
  • cellulose (polymer of glucose)