Organic Chemistry 1 - Homologous Series and Reactions

Question 1

Substitution Reaction

Answer 1

One functional group is substituted for another (eg -Cl for -OH, or -H for -Br). Two reactants and two products.

Question 2

Conditions for substitution reaction between an alkane and a hydrogen halide

Answer 2

UV light

Question 3

Substitution Reaction - Synthesis of Alcohols

Answer 3

Haloalkane passed through sodium hydroxide (NaOH) or potassium hydroxide (KOH) to produce an alcohol.

Question 4

Why can alkenes undergo addition reactions?

Answer 4

Presence of a double bond

Question 5

Reactants for the hydrogenation of alkenes (Addition)

Answer 5

alkene + hydrogen gas

Question 6

Conditions for the hydrogenation of alkenes (Addition)

Answer 6

Ni catalyst and 150 degrees C temperature

Question 7

What is produced when an alkene reacts with a hydrogen halide?

Answer 7

A haloalkane (eg a chloroalkane when an alkene reacts with HCl)

Question 8

Conditions for reaction between an alkene and a hydrogen halide

Answer 8

room temperature (standard lab conditions)

Question 9

Describe what happens when an alkene is bubbled through bromine water.

Answer 9

The alkene reacts with bromine to produce a dibromoalkane (bromine atom added to either side of the double bond)

Question 10

Conditions for the Halogenation of Alkenes (Addition)

Answer 10

room temperature (standard lab conditions)

Question 11

Conditions for the hydration of alkenes to form an alcohol

Answer 11

Phosphoric acid catalyst, 300 degrees C and 60-70 atm pressure

Question 12

Describe the hydration of ethene (reactants and products)

Answer 12

Ethene reacts with steam to produce ethanol

Question 13

What happens when an ester is hydrolysed in acidic conditions?

Answer 13

Ester link is broken and water is added, producing a carboxylic acid and an alcohol

Question 14

Conditions required for hydrolysis of an ester

Answer 14

Aqueous acid (H+) or strong alkali (OH-)

Question 15

Green Chemistry Principles

Answer 15

The Green Chemistry approach strives to achieve sustainability at the molecular level.

Question 16

Homologous series

Answer 16

A series of organic compounds that have a similar chemical structure and chemical properties

Question 17

Organic compounds

Answer 17

Compounds consisting of carbon atoms most commonly covalently bonded to hydrogen, nitrogen, phosphorus or oxygen atoms

Question 18

Functional group

Answer 18

Specific groups of atoms within a compound that affect the properties of the compound.

Question 19

Alkane General Formula

Answer 19

CnH2n+2

Question 20

Alkene General Formula

Answer 20

CnH2n

Question 21

Haloalkane General Formula

Answer 21

CnH2n+1 X

Question 22

Isomers

Answer 22

Are organic molecules having the same molecular formula but a different structural formula.

Question 23

Why do the longer hydrocarbon chains take more heat energy to change state from solid to liquid or liquid to gas?

Answer 23

The longer the chain, the more intermolecular forces there are between the molecules, and require more energy to break.

Question 24

When the hydrocarbon goes through a state change of liquid to gas, which bonds are broke?

Answer 24

Weak intermolecular forces are broken when the hydrocarbon reaches its boiling point and transitions from liquid to a gas. The covalent bonds between the atoms do not beak. This would required a higher amount of energy.

Question 25

What is cracking

Answer 25

Cracking is an example of a thermal decomposition reaction, where large organic molecules (usually alkanes) are broken down into smaller molecules (usually a smaller alkane and an alkene) using heat and a catalyst.

Question 26

Compare complete and incomplete combustion (of hydrocarbons, alcohols or esters)

Answer 26

In complete combustion a fuel is burned in excess oxygen:
fuel + oxygen → carbon dioxide + water
In incomplete combustion the fuel is burned in limited oxygen
fuel + oxygen → carbon monoxide + water or
fuel + oxygen → carbon + water

Question 27

Substitution reaction

Answer 27

Oneatom(or functional group) is swapped with another atom (or functional group).
Alkanesundergo asubstitution reactionwithhalogensin the presence of light.

Question 28

Addition reaction

Answer 28

Double bond breaks and atoms are added to either side

Question 29

Bromine water test (including equation, including conditions)

Answer 29

A test to determine whether a solution or gas contains alkenes. Performed at room temperature with bromine water (Br2(aq))
Bromine water goes from orange or brown to colourless (decolourises) when it is mixed with an alkene. There is no change upon mixing with alkanes.
Br2 + CH2CH2 → CH2BrCH2Br

Question 30

Hydrogenation (addition reaction with H2) equation and conditions

Answer 30

Alkene + hydrogen (150degreesC and Ni catalyst)→ alkane

Question 31

Hydration (addition reaction with H2O) equation and conditions

Answer 31

Alkene + water (steam) (phosphoric acid catalyst, 60-70 atm + 300degrees C) → alcohol

Question 32

Ethanol production (including advantages and disadvantages) Fermentation of glucose

Answer 32

Fermentation of glucose:
C6H12O6 (yeast catalyst) → C2H5OH + CO2
Advantages: Simple method and uses renewable resources (glucose from sugar cane or sugar beet)
Disadvantages: Not a continuous process, slow reaction and produces low purity ethanol that requires purification

Question 33

Ethanol production (including advantages and disadvantages) Hydration

Answer 33

Ethene + steam
C2H4 + H2O (g) → C2H5OH
Advantages: Continuous process, reaction is fast and produces high purity ethanol
Disadvantages: Uses non-renewable resources, equipment is expensive

Question 34

Alcohol Homologous Series

Answer 34

Organic compounds containing a hydroxyl (R-OH) group are called alcohols

Question 35

Carboxylic acid functional group and naming conventions

Answer 35

Functional group is R-COOH, name ends in -oic acid. Carbon in functional group is designated carbon number 1 in all cases

Question 36

Alkyl Halides

Answer 36

Organic compounds containing halogens are called alkyl halides. The halo group is added as a prefix to the name.

Question 37

Ester functional group and naming conventions

Answer 37

Functional group is R1-COO-R2. The carbon double bonded to oxygen is designated carbon number 1 in the main chain (the -oate, eg methanoate). The other carbon chain is designated as an alkyl group (eg methyl) and named as a prefix.

Question 38

Can methyl methanal exist?

Answer 38

No - the methyl group would be an extension to the main chain so this would be ethanal

Question 39

Can 2-ethylbutane exist?

Answer 39

No - the ethyl group would be classed as an extension of the main chain. This would be 3-methylpentane (draw it out!).

Question 40

Differences between ketones and aldehydes

Answer 40

Ketones have the C=O group in the middle of the carbon chain, whereas aldehydes have the C=O group at either end. Aldehydes can be oxidised to form carboxylic acids, whereas ketones cannot be oxidised.

Question 41

Designation of alcohols as primary, secondary or tertiary

Answer 41

Primary alcohols have zero or one carbon bonded to the carbon containing the functional group. Secondary alcohols have two carbons bonded to the carbon containing the functional group. Tertiary alcohols have three carbons bonded to the carbon containing the functional group.

Question 42

Differences in oxidation of primary, secondary or tertiary alcohols

Answer 42

Primary alcohols can be oxidised partially to form aldehydes, or completely to form carboxylic acids. Secondary alcohols can be oxidised to form ketones but no further. Tertiary alcohols cannot be oxidised.