topic 6 definitions

Question 1

hydrocarbon

Answer 1

A compound exclusively consisting of hydrogen and carbon atoms.

Question 2

homologous series

Answer 2

Series of organic compounds with the same functional group and general formula. Consecutive members of a series differ by -CH2

Question 3

functional group

Answer 3

a group of atoms responsible for the characteristic reactions of a particular compound.

Question 4

polymerisation

Answer 4

Joining together lots of simple molecules (monomers) to form a giant molecule (a polymer)

Question 4

addition

Answer 4

Joining two or more molecules together to form a larger molecule. Hydration is the addition of a H, molecule. Halogenation involves the addition of a halogen. Hydrogenation is the addition of H2. Electrophilic addition describes all the above examples.

Question 5

repeating unit

Answer 5

a simplest pattern (group of elements bonded together) of the polymer that, upon translation, reproduces the whole structure.

Question 6

substitution

Answer 6

When one species is replaced by another.

Question 6

elimination

Answer 6

When a small group of atoms breaks away from a larger molecule to form a C=C bond.

Question 7

hydrolysis

Answer 7

Breaking bonds in a molecule by reaction with H2O.

Question 8

dehydration

Answer 8

Reaction in which water is eliminated from a starting material.

Question 9

saturated

Answer 9

Refers to a compound with all the C-C bonds being single bonds.

Question 10

heterolytic fission

Answer 10

The process of breaking a covalent within a molecule leading to the formation of ions. Upon bond breaking, one atom receives the electron pair and becomes a negatively charged ion. Other atom becomes a cation, e.g.
Br-Br → Br+ + Br-

Question 11

homolytic fission

Answer 11

The process of breaking a covalent within a molecule leading to the formation of radicals. Upon bond breaking, each atom receives one electron from the bonding pair and both atoms become radicals, e.g.
Br-Br → Br. + Br.

Question 12

radicals

Answer 12

a species with an unpaired electron. Represented in mechanisms by a single dot.

Question 13

free radical substitution

Answer 13

Photochemical reaction (requires UV light) between halogens and alkanes to form halogenoalkanes. Initiation is the process of forming the radicals from a molecule by homolytic fission. Propagation is the formation of a new radical and a new molecule from some radical and other molecule. Termination concludes the mechanism and is the process of two radicals joining together to form a molecule. Polysubstitution (multiple substitution) is often a problem.

Question 14

stereoisomerism

Answer 14

Occurs when two double bonded carbon atoms each have two different atoms or groups attached to them. Includes E/Z isomerism and cis/trans isomerism. This is a consequence of a restricted rotation around the C=C double bond.

Question 14

structural isomerism

Answer 14

Occurs when species have the same molecular formula, but a different structural formula, e.g. C6H12 can be ascribed to hex-1-ene, but also to 2-methylpent-1-ene.

Question 15

saturated hydrocarbons

Answer 15

Hydrocarbons which contain only single (sigma) bonds between carbon atoms.

Question 16

unsaturated hydrocarbons

Answer 16

Hydrocarbons which contain at least one carbon-carbon double bond.

Question 17

cracking

Answer 17

Breaking long chain alkanes into smaller, more useful hydrocarbons. Helps to convert low demand hydrocarbons into more highly demanded ones.

Question 18

reforming

Answer 18

Processing of straight chain hydrocarbons into branched chain alkanes and cyclic hydrocarbons for efficient combustion. Done so there’s no knocking.

Question 19

knocking

Answer 19

Alkanes explode of their own accord when the fuel/air mixture in an engine is compressed.

Question 20

complete combustion

Answer 20

Produces fully oxidised products (e.g. CO2) as opposed to incomplete combustion (produces CO).

Question 21

catalytic converters

Answer 21

Get rid of pollutants in cars by using platinum catalyst to convert them to harmless gases, e.g. 2NO + CO → N2 + CO2

Question 22

biofuels

Answer 22

Fuels made from living matter over a short period of time. e.g. biodiesel made by refining renewable fats and oils such as vegetable oil.

Question 23

recycling

Answer 23

Conversion of a waste from polymer into other useful materials.

Question 24

incinerator

Answer 24

a device for converting polymer waste into energy.

Question 25

feedstock

Answer 25

For conversion of polymer waste into compounds that can be used to synthesise new polymers.

Question 26

biodegradable

Answer 26

Refers to a polymer that can be decomposed by microbes. Usually has polar groups (e.g. ester, amide).

Question 27

electrophile

Answer 27

Electron pair acceptor in an organic mechanism. Attracted to areas with lot of electrons/high negative charge.

Question 28

nucleophilic

Answer 28

Electron pair donors in an organic mechanism. Attracted to electron-deficient areas.

Question 29

carbocation

Answer 29

A carbon atom bearing a positive charge.

Question 30

electron releasing group

Answer 30

a group that releases the electrons towards the atom it is joined to.

Question 31

markovnikoff’s rule

Answer 31

Weak statement - when adding a hydrogen halide to an unsymmetrical alkene, the major product is formed from hydrogen adding to the carbon with more hydrogens, and halide adding to the carbon with fewer hydrogens. Strong statement - The major product of an electrophilic addition to the unsymmetrical alkene results from a reaction proceeding via the most stable carbocationic intermediate (stability increases in the order: primary

Question 32

distillation with addition

Answer 32

Performing the reaction under distillation conditions whilst adding one of the reagents. The product distills off as it forms in case of oxidation of an alcohol to an aldehyde.

Question 33

solvent extraction

Answer 33

A method for separating a compound from a mixture by causing it to move to another solvent.

Question 34

fractional distillation

Answer 34

a distillation that utilises a fractionating column (packed glass beads that provide a surface for the vapour to condense and evaporate again). Used to separate liquids of similar boiling points.