Organic chemistry Flashcards

1
Q

What are organic compounds?

A

Any carbon compound except for the very simplest (carbon dioxide, carbon monoxide, the carbonates and the hydrogencarbonates)

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2
Q

What are hydrocarbons?

A

Compounds that only contain hydrogen and carbon atoms.

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3
Q

What is an empirical formula?

A

The simplest whole number ratio of the atoms in a compound.

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4
Q

What is a molecular formula?

A

It counts the actual number of each type of atom present in a molecule.

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5
Q

What is a homologous series?

A
  • A series of compounds with similar chemical properties because they have the same functional group.
  • Each member differs from the next one by one CH₂.
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6
Q

What is the general formula of alkanes?

A

CₙH₂ₙ₊₂

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7
Q

What is a functional group?

A

An atom or a group of atoms that determine the chemical properties of a compound.

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8
Q

What is a structural formula?

A

Shows how the atoms in a molecule are joined together.

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9
Q

What is a displayed formula?

A
  • It shows all the bonds in the compound as individual lines.
  • Each line represents a pair of shared electrons in a covalent bond.
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10
Q

What are alkanes?

A

A homologous series of similar hydrocarbons in which all the carbons are joined to each other with single covalent bonds.

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11
Q

What are alkenes?

A

A homologous series of hydrocarbons which contain a carbon=carbon double bond.

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12
Q

What are structural isomers?

A

Compounds with the same molecular formula but different structural formulae.

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13
Q

What are alcohols?

A

A homologous series of compounds which all contain an OH functional group attached to a hydrocarbon chain.

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14
Q

What happens when hydrocarbons combust in excess oxygen?

A

It gives rise to carbon dioxide and water, together with the release of a large amount of heat energy.

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15
Q

What is a substitution reaction?

A

When an atom or group of atoms is replaced by a different atom or group of atoms.

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16
Q

What is an addition reaction?

A

A chemical reaction in which one molecule adds to another without taking anything away, to form a single product.

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17
Q

What is the origin of crude oil?

A
  • Millions of years ago, plants and animals living in the sea died and fell to the bottom
  • Layers of sediment formed on top of them and their shells and skeletons formed limestone.
  • The soft tissue was gradually changed by heat and high pressure into crude oil.
  • Crude oil is a finite, non-renewable resource.
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18
Q

What is crude oil a mixture of?

A

Hydrocarbons.

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19
Q

What physical properties change when the number of carbon atoms in hydrocarbon molecules increases?

A
  • Boiling point increases (Large molecules are attracted to each other more strongly than smaller ones. More energy is needed to break these stronger intermolecular forces of attraction).
  • The liquids become less volatile (same reason as boiling point).
  • The liquids become more viscous.(Because of the stronger forces of attraction between molecules).
  • The liquids become darker in colour.
  • They do not burn as easily.
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20
Q

What does volatile mean?

A

A substance that evaporates easily.

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20
Q

What does viscous mean?

A

A liquid that is resistant to flow.

21
Q

What do fractions of crude oil contain?

A

Mixtures which each contain a narrow range of sizes of hydrocarbons with similar boiling points.

22
Q

What process is used to separate crude oil into fractions?

A

Fractional distillation.

23
Q

Describe the process of fractional distillation?

A
  • Crude oil is heated until it boils and the vapours pass into a fractionating column (which is cooler at the top and hotter at the bottom).
  • How far up the column a particular hydrocarbon moves depends on its boiling point.
  • When the temperature of the column falls to the boiling point of the hydrocarbon, the hydrocarbon condenses and can be removed.
24
Q

List the different fractions from highest boiling point to lowest boiling point?

A
  • Bitumen
  • Fuel oil
  • Diesel oil
  • Kerosene
  • Gasoline
  • Refinery gases
25
Q

What is a fuel?

A

A substance which, when burned, releases heat energy.

26
Q

Why are various fractions used as fuels?

A

All hydrocarbons burn in air (oxygen) to form carbon dioxide and water, releasing a lot of heat in the process.

27
Q

When does incomplete combustion happen?

A

If there isn’t enough air (oxygen).

28
Q

What is formed from incomplete combustion?

A

Carbon (soot) or carbon monoxide. Water is also formed.

29
Q

What are refinery gases a mixture of?

A

Methane, ethane, propane, butane.

30
Q

What are refinery gases used for?

A

Used as liquefied petroleum gas for domestic heating and cooking.

31
Q

What is petrol used for?

A

Used as a fuel in cars.

32
Q

What is kerosene used for?

A

Used as a fuel for jet aircraft, as domestic heating oil, and as ‘paraffin’ for small heaters and lamps.

33
Q

What is diesel used for?

A

Used as a fuel for buses, lorries, some cars and some railway engines. Some is also converted to other more useful organic chemicals in a process called cracking.

34
Q

What is fuel oil used for?

A

Used as a fuel for ships and for industrial heating.

35
Q

What is bitumen used for?

A

It is a thick, black material, which is melted and mixed with small pieces of rock to make the top surface of roads.

36
Q

Problems associated with the burning of fossil fuels derived from crude oil?

A
  • The carbon dioxide produced when hydrocarbons are burnt is a greenhouse gas.
  • Greenhouse gases trap the heat radiated from the Earth’s surface and this leads to climate change.
37
Q

When is acid rain formed?

A
  • When water and oxygen in the atmosphere react with sulfur dioxide to produce sulfuric acid (or with various oxides of nitrogen to give nitric acid).
  • Sulfuric acid is an important component of acid rain.
38
Q

How does the burning of fossil fuels lead to acid rain?

A
  • Fossil fuels contain a small amount of sulfur.
  • When the fuel is burnt, the sulfur reacts with oxygen, producing sulfur dioxide.
  • When sulfur dioxide reacts with oxygen and water in the atmosphere, it can be converted to sulfuric acid.
  • Sulfuric acid contributes to acid rain.
39
Q

How can petrol engines cause acid rain?

A
  • The high temperature reached in the engine allows nitrogen and oxygen in the air to combine to produce oxides of nitrogen.
  • These nitrogen oxides can be converted into nitric acid which contributes to acid rain.
40
Q

Why is acid rain a problem?

A
  • Acid rain damages trees and harms fish in lakes.
  • Limestone buildings and marble statues are attacked by acid rain.
41
Q

Why is cracking needed?

A
  • There are far too many long-chain hydrocarbons, which are not in such high demand and are not as profitable to sell.
  • There are not enough shorter-chain hydrocarbons that can be used as fuel for cars. Higher demand.
42
Q

What is cracking?

A

A process in which long chain alkanes are converted to alkenes and shorter chain alkanes.

43
Q

What main condition is need for cracking?

A

The fuel oil fractions is heated at about 600-700°C.

44
Q

What useful things are produced from cracking?

A
  • Petrol
  • Alkenes that can be used for making polymers.
45
Q

What properties do homologous series have?

A
  • Have the same functional group.
  • Have similar chemical properties.
  • Show a trend in physical properties.
  • Can be described by the same general formula.
  • Differ from the next by a CH₂ unit.
46
Q

Which alkanes are gases at room temperature?

A
  • The first 4.
  • Methane, Ethane, Propane, Butane
  • The rest are liquids
47
Q

How reactive are alkanes?

A

Fairly unreactive, quite inert.

48
Q

What is needed for a substitution reaction with alkanes and halogens.

A

Ultraviolet radiation

49
Q

What is mono-substitution?

A

When only one hydrogen atom in the alkanes is replaced by a halogen atom.

50
Q

What are the names of the catalysts used in catalytic cracking.

A

Alumina and silica.