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Organic Chemistry Flashcards

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1
Q

What is organic chemistry?

A

The chemistry of CARBON ATOMS

Carbon forms a vast umber of compounds because it can form strong covalent bonds with itself

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2
Q

What is a functional group?

A

A specific atom or group of atoms which confer certain physical and chemical properties onto the molecule

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3
Q

What is a homologous series?

A

Organic compounds with the same functional group but a different number of carbon atoms are said to belong to the same HOMOLOGOUS SERIES.

Each member has the same functional group
Each member has the same general formula
Each member has similar chemical properties

As the homologous series is ascended, the size of the molecule increases, which has an effect on physical properties, such as boiling point and density

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4
Q

What is the general formula of alkenes?

A

CnH2n

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5
Q

What is the displayed formula?

A

Shows the spatial arrangement of all the atoms and bonds in a molecule

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6
Q

What is the molecular formula?

A

Shows the actual number of each atom in a molecule, one molecule at a time

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7
Q

What is crude oil?

A

A finite resource which we find in the Earth’s crust, which is a mixture of hydrocarbons which also contain natural gas.

It is a thick, sticky, black liquid that is found in porous rick which was formed over millions of years ago from the effects of high pressures and temperatures on the remains of plants and animals

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8
Q

What is an alkane?

A

A group of saturated hydrocarbons.

General formula is CnH2n+2

Colourless compounds which have a gradual change in their physical properties as the number of carbon atoms in the chain increases.

Generally uncreative compounds but they undergo combustion reactions and can be cracked into smaller molecules as well as reacting with halogens in the presence of light

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9
Q

What does saturated mean?

A

Containing the greatest number of hydrogen atoms.

They only have single carbon-carbon bonds and there are no double bonds

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10
Q

Why is crude oil so useful?

A

Crude oil itself is NOT useful, but the different hydrocarbons that make up the mixture, called fractions are EXTREMELY VALUABLE, with each fraction having many different applications.

Each fraction consists of groups of hydrocarbons of SIMILAR CHAIN LENGTHS.

These fractions in petroleum can be separated in FRACTIONAL DISTILLATION.

The size and length of these fractions determine which fraction they will be separated into.

Most fractions contain MANY ALKENES

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11
Q

What is fractional distillation?

A

A separation technique used to separate in this example CRUDE OIL in a fractionating column, which is very hot at the bottom and cool at the top

Crude oil enters the fractionating column and is heated so vapour rises

Vapours of hydrocarbons with very high boiling points immediately condense into liquid at the higher temperatures lower down and are tapped off at the bottom of the column

The fractions containing SMALLER hydrocarbons are collected at the TOP of the fractionating column as gases

The fractions containing BIGGER hydrocarbons are collected at the lower sections of the fractionating column

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12
Q

What are petrochemicals?

A

Chemicals obtained from the process of fractional distillation of petroleum

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13
Q

What can petrochemicals be useful for?

A
  • Useful in most transport lines
  • Liquidified petroleum gas (domestic heating and cooking)
  • Petrol (Fuel for cars)
  • Kerosene (Jet fuel (paraffin))
  • Diesel (Diesel engines (gas oil))
  • Heavy fuel oil (Ships and power stations)
  • Bitumen (Surfacing roads and roofs)
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14
Q

What do the properties of hydrocarbons depend on?

A

The size of the molecule, (how many carbons there are)

Functional group

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15
Q

What happens to the properties of hydrocarbons as their sizes increase and why?

A

Boiling point increases due to the molecules getting larger so there are more intermolecular forces of attraction between the molecules so more energy is required to break these forces and separate the molecules

Viscosity also increases with chain length.

As hydrocarbons increase in size, flammability DECREASES.

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16
Q

What is viscosity?

A

Refers to the FLOW of a liquid

High viscosity liquids are THICK and flow less easily

Low viscosity means the liquid is RUNNY

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17
Q

What is complete combustion?

A

When WATER and CARBON DIOXIDE are formed at the end of a reaction

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18
Q

What is the equation for the combustion of methane?

A

CH4 + 2O2 –> CO2 + 2H2O

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19
Q

Why are alkenes unsaturated compounds?

A

Because they have double C–C bonds, meaning that there is not the maximum amount of hydrogen atoms present

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20
Q

What is cracking?

A

A process whereby long-chain hydrocarbons are broken down and CRACKED to produce smaller chain hydrocarbons

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21
Q

What are the 2 methods for cracking?

A

Catalytic cracking and steam cracking

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22
Q

What is catalytic cracking?

A

Involves heating the hydrocarbon molecules to around 470-550°C to vaporise them

Then the vapours pass over a hot powdered catalyst of aluminium oxide

This process breaks covalent bonds in the molecules as the come into contact with the surface of the catalyst causing THERMAL DECOMPOSITION where the molecules are broken up in random ways to produce mixtures of SMALLER alkanes and alkenes

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23
Q

What is steam cracking?

A

Involves using slightly higher temperatures than Catalytic cracking, and produces more ring structures and UNSATURATED COMPOUNDS

The vaporised hydrocarbons are mixed with STEAM and heated to a high temperature which induces cracking and forms the smaller alkanes and alkenes

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24
Q

What happens when we write equations for cracking?

A

The C and H atoms must add to make the same number om both sides, eg.

C6H16 –> C4H10 + C2H4

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25
Q

What are alkenes?

A

A hydrocarbon compound with ATLEAST ONE double bond between two of the carbon atoms in the chain

The general formula of alkenes is CnH2n

They are MORE REACTIVE than ALKANES due to the presence of the C–C double bond, so they can take part in reactions in which alkanes cannot, so they are more useful and desired than alkanes

They can be used to make polymers and are the starting materials for the production of many other chemicals

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26
Q

What is the bromination of Ethene?

A

Where ethene undergoes an ADDITION REACTION in which atoms of a simple molecule add across the C–C double bonds

27
Q

How can we tell apart alkenes and alkanes?

A

Alkenes can undergo reactions which alkanes CANT, so we can use a simple test called the BROMINE WATER TEST to tell them apart

28
Q

How does the bromine water test work?

A

Bromine water is a coloured (orange) solution, so when bromine water is added to two samples of an alkane and an alkene, when added to the alkane there will be no colour change because bromine and the alkane wont react, so the bromine remains in solution.

However when the bromine water is added to the alkene, the bromine atoms add across the C–C double bond, so the solution no longer contains free bromine so it loses its colour

29
Q

What is the functional group of an alkene?

A

C–C double bond

30
Q

What is special about alkenes being unsaturated?

A

They can make more bonds with other atoms by opening up the C–C bond and allowing incoming atoms to form another single bond with each carbon atom

31
Q

What happens when alkenes are combusted?

A

Alkenes can undergo complete and incomplete combustion but because of the higher carbon to hydrogen ratio they tend to undergo incomplete combustion, producing a smoky flame in the air

32
Q

When does complete combustion occur?

A

When there is EXCESS OXYGEN

33
Q

When does incomplete combustion occur?

A

When there is INSUFFICIENT OXYGEN to burn.

Carbon MONOXIDE and SOOT in the form of carbon can be formed in this case

34
Q

What is hydrogenation?

A

When alkenes undergo ADDITION REACTIONS with HYDROGEN in which an ALKANE is formed.

This occurs at 150°C using a NICKEL CATALYST

35
Q

What is a hydration reaction?

A

Where water is added to the molecule when an alkene undergoes an addition reaction with steam where an ALCOHOL is formed

36
Q

What is halogenation?

A

When a halogen participates in addition reactions with alkenes, eg. Bromine

37
Q

What is the functional group of an alcohol?

A

(-OH)

38
Q

What is the formula of an alcohol?

A

CnH2n+1OH

39
Q

How can ethanol be produced?

A

By fermentation where sugar or starch is dissolved in water and yeast is added. It is fermented between 15 and 35°C WITHOUT Oxygen for a few days, and yeast enzymes break down the sugar into glucose. The yeast is killed off once the concentration of the alcohol reaches 15%

40
Q

How can ethanol be used?

A

Alcoholic drinks, fuels, solvents

41
Q

What does Ethanol look like?

A

A colourless liquid that dissolves in water to form NETRAL solutions

42
Q

Why are methanol and ethanol such good solvents?

A

Because they can dissolve many substances that water CANNOT , such as fats and oils, but can also dissolve most of the substances that water CAN

43
Q

What happens when alcohols undergo complete combustion?

A

Forms CARBON DIOXIDE and WATER

44
Q

How are carboxylic acids formed?

A

When an alcohol undergoes OXIDATION, carboxylic acids are produced

45
Q

What is the general formula of a carboxylic acid?

A

CnH2n+1COOH

46
Q

What happens as the size of the carboxylic acid increases?

A

Its viscosity increases (so it becomes thicker) and its boiling point increases, (more intermolecular forces)

47
Q

What happens when a carboxylic acid reacts with metals?

A

Forms SALT + Hydrogen

48
Q

What happens when carboxylic acids react with hydroxides?

A

Salt and Water are formed in a NEUTRALISATION reaction

49
Q

What happens when a carboxylic acid reacts with carbonates?

A

Metal salt, water and CO2 are produced

50
Q

What happens when carboxylic acids and alcohols react?

A

ESTERS are formed in ESTERIFICATION

51
Q

What is the functional group of an ester?

A

(-COO)

52
Q

Why are carboxylic acids weak acids?

A

Because they only PARTLY IONISE when dissolved in water (pH values between 3 and 7)

Ethanoic acids for example is around 95% undissociated

So out of 100 molecules, only about 5 actually ionise

53
Q

What are polymers?

A

Polymers are large molecules of high relative molecular mass and are made by linking together large numbers of smaller molecules called MONOMERS

54
Q

What are monomers?

A

Monomers are small molecules connected to adjacent repeating units within a polymer via adjacent bonds

55
Q

What are the different types of polymers?

A

Synthetic (man made, such as plastics) and biological, (natural ones, such as DNA)

56
Q

What do polymerisation reactions often require?

A

HIGH PRESSURES and the use of a CATALYST

57
Q

How do we represent polymer formula on paper?

A

We use their REPEATING UNIT

https://cdn.savemyexams.co.uk/wp-content/uploads/2020/01/Drawing-repeating-units-1024x440.png

58
Q

What is condensation polymerisation?

A

Where two different monomers are linked together to form a polymer + one water molecule PER LINKAGE

The monomers have TWO FUNCTIONAL GROUPS PRESENT, where they are at EACH END of the monomer.

The functional groups at the ends of one monomer react with the functional group on the end of the other monomer, creating long chains of ALTERNATING MONOMERs and producing WATER

59
Q

What are amino acids?

A

Small molecules containing the amino, NH2, and the carboxylic acid functional group

There are 20 naturally occurring amino acids and they all have the same general structure

60
Q

What are polypeptides?

A

Polypeptides are condensation polymers which are formed from AMINO ACID monomers joined together by peptide links

61
Q

What is DNA?

A

A large molecule which consists of 4 different monomers called nucleotides containing genetic information encoding instructions to which organisms need to develop and function correctly.

Nucleotides form two strands that intertwine causing the famous double helix.

The nucleotides contain smaller molecules called BASES which are abbreviated to A, T, C and G which are bound together by polymerisation

62
Q

What are simple carbohydrates?

A

Monosaccharides, such as SUGARS like fructose and glucose

63
Q

What are complex carbohydrates?

A

Polysaccharides, such as STARCH and CELLULOSE

the monomers which form these are sugars

64
Q

What are protein based natural polymers?

A

Haemoglobin, Antibodies and Enzymes

Chemistry (28 decks)

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