Types Of Reactions In Organic Chemistry (chpt. 23)

Question 1

Substitution reaction

Answer 1

A chemical reaction in which an atom or group of atoms in a molecule is replaced by another atom or group of atoms

Question 2

Mechanism

Answer 2

The mechanism of a reaction is the detailed step-by-step description of the overall reaction occurs occurs

Question 3

Chain reaction

Answer 3

A reaction that continues on and on because a product from one step of the reaction is a reactant for another step of the reaction

Question 4

Evidence for the reaction of mono chlorination of methane

Answer 4

• takes place when exposed to UV light (free radicals involved)
• ethane is found in products (methyl free radicals present and react together to form ethane)
• tetramethyl lead speeds up reaction (only a mechanism involving free radicals would be affected by adding free radicals)
• thousands of chloromethane molecules are formed for every photon of light absorbed (chain reaction)

Question 5

Addition reaction

Answer 5

One in which two or more molecules react together to form a single molecule

Question 6

Hydrogenation reaction

Answer 6

Involves hydrogen reacting with unsaturated substances ( C double / treble bonds )

Question 7

Polymers

Answer 7

Long-chain molecules made by joining together many small molecules

Question 8

Repeating unit of a polymer

Answer 8

The part of the polymer whose repetition completes the complete polymer chain except for the end groups

Question 9

Elimination reaction

Answer 9

One in which a small molecule is removed from a larger molecule to leave a double bond in the larger molecule
E.g removal of water from an alcohol to form an alkene

Question 10

Example of an oxidising agent

Answer 10

KMnO4

Question 11

What element and catalyst are commonly used in reduction reactions

Answer 11

Hydrogen & nickel catalyst

Question 12

Explain the acidic nature of carboxylic acid groups

Answer 12

• Inductive effect → C=O has the effect of drawing electrons away from the -OH and this facilitates the ionisation of the H in the OH
• Stability of carboxylate ion → so stable that carboxylic acid loses a proton

Question 13

Organic synthesis

Answer 13

The process of making organic compounds from simpler starting materials
↳ involves bond breaking & making
↳ forms useful products e.g aspirin, paracetamol

Question 14

Recrystallisation

Answer 14

The process of repeated crystallisation in order to purify a solid or obtain more satisfactory crystals of a solid that is already pure

Question 15

Chromatography

Answer 15

A separation technique in which a mobile phase carrying a mixture moves in contact with a selectively adsorbent stationary phase

Question 16

What is chromatography used for?

Answer 16

Separate different substances in a mixture
Identifying & measuring amounts of these substances

Question 17

Principle of chromatography

Answer 17

Separation of a mixture of components occurs as a result of selective adsorbance of the components of the mixture on a stationary phase while carried by a mobile phase

Question 18

Principle of infra-red spectrometry

Answer 18

Organic compounds absorb infra-red radiation of certain frequencies
The combinations of frequencies that are absorbed depend on the bonding within the molecule and are unique to that particular molecule

Question 19

Principle of ultraviolet absorption spectrometry

Answer 19

Absorbance is directly proportional to the concentration of a substance