Homologous Series

Question 1

What is a homologous series?

Answer 1

A family of compounds with similar chemical properties and the same general formula.

A homologous series includes alkanes, alkenes, and cycloalkanes.

Question 2

What is the general formula for alkanes?

Answer 2

CₙH₂ₙ₊₂

Alkanes are saturated hydrocarbons.

Question 3

What is the general formula for alkenes?

Answer 3

CₙH₂ₙ

Alkenes are unsaturated hydrocarbons.

Question 4

What is the general formula for cycloalkanes?

Answer 4

CₙH₂ₙ

Cycloalkanes are also saturated hydrocarbons.

Question 5

What type of molecule are alkanes described as?

Answer 5

Saturated molecules.

Alkanes contain only single carbon-to-carbon bonds.

Question 6

What type of molecule are alkenes described as?

Answer 6

Unsaturated molecules.

Alkenes contain at least one carbon-to-carbon double bond.

Question 7

What is a functional group?

Answer 7

A part of a molecule responsible for its characteristic chemical properties.

In alkenes, the functional group is the carbon-to-carbon double bond.

Question 8

What is the test for unsaturated hydrocarbons?

Answer 8

Decolourisation of bromine solution.

Alkenes will decolourise bromine solution instantly.

Question 9

What is the name of the reaction where alkenes react with hydrogen?

Answer 9

Hydrogenation.

This reaction produces the corresponding alkane.

Question 10

What is the name of the reaction where alkenes react with water?

Answer 10

Hydration.

This reaction produces alcohols.

Question 11

What are isomers?

Answer 11

Molecules with the same molecular formula but different structures.

Examples include pentane, dimethylpropane, and methylbutane.

Question 12

What happens to melting and boiling points as the number of carbon atoms in hydrocarbons increases?

Answer 12

They increase.

This is due to increased London dispersion forces.

Question 13

What type of intermolecular force is primarily responsible for the physical properties of alcohols?

Answer 13

Hydrogen bonds.

Alcohols have higher boiling points due to hydrogen bonding.

Question 14

What is the general formula for alcohols?

Answer 14

CₙH₂ₙ₊₁OH

Alcohols contain a hydroxyl functional group.

Question 15

What are the three types of alcohols?

Answer 15

Primary, secondary, and tertiary.

The classification depends on the number of carbon atoms bonded to the carbon with the hydroxyl group.

Question 16

What is a diol?

Answer 16

An alcohol with two hydroxyl groups.

Example: Ethylene glycol.

Question 17

What is a triol?

Answer 17

An alcohol with three hydroxyl groups.

Example: Glycerol.

Question 18

What is the functional group in carboxylic acids?

Answer 18

Carboxyl group (–COOH).

Carboxylic acids are also known as alkanoic acids.

Question 19

What is the general formula for carboxylic acids?

Answer 19

CₙH₂ₙO₂

This formula reflects the presence of the carboxyl group.

Question 20

True or False: Alkanes can decolourise bromine solution.

Answer 20

False.

Alkanes do not react with bromine solution.

Question 21

What functional group is characteristic of carboxylic acids?

Answer 21

–COOH

The carboxyl group.

Question 22

What is the general formula for alkanoic acids?

Answer 22

CnH2n+1COOH

Question 23

Identify the example carboxylic acid: CH3CH(CH3)CH2CH(CH3)COOH.

Answer 23

2-methylbutanoic acid

Question 24

As the carbon chain length increases, what happens to the melting and boiling points of carboxylic acids?

Answer 24

They increase

Question 25

As the carbon chain length increases, what happens to the volatility of carboxylic acids?

Answer 25

It decreases

Question 26

What intermolecular forces increase as the carbon chain length increases?

Answer 26

London dispersion forces

Question 27

Hydrogen bonds are ________ than pd-pd interactions.

Answer 27

stronger

Question 28

What is required to break hydrogen bonds in order to boil propanoic acid?

Answer 28

more energy

Question 29

What is the general equation for the reaction of carboxylic acids with metal oxides?

Answer 29

acid + metal oxide → salt + water

Question 30

What is the name of a salt made from a carboxylic acid?

Answer 30

It ends in ‘-oate’

Question 31

What is the general equation for the reaction of carboxylic acids with metal hydroxides?

Answer 31

acid + metal hydroxide → salt + water

Question 32

What is the balanced formula equation for propanoic acid reacting with sodium hydroxide?

Answer 32

CH3CH2COOH + NaOH → sodium propanoate + H2O

Question 33

What is the general equation for the reaction of carboxylic acids with metal carbonates?

Answer 33

acid + metal carbonate → salt + carbon dioxide + water

Question 34

What happens to the hydrogen from the carboxyl group when forming salts from carboxylic acids?

Answer 34

It is replaced by a metal ion

Question 35

What is the product of oxidizing primary alcohols?

Answer 35

aldehydes

Question 36

What is the product of oxidizing secondary alcohols?

Answer 36

ketones

Question 37

Tertiary alcohols ________ readily oxidise.

Answer 37

do not

Question 38

What color change occurs when acidified potassium dichromate is reduced?

Answer 38

orange to green

Question 39

In aldehydes, the carbonyl group is found ________ in the carbon chain.

Answer 39

at the end

Question 40

What is the name ending for aldehydes?

Answer 40

–al

Question 41

What is the carbonyl functional group sequence for aldehydes?

Answer 41

—CHO

Question 42

In ketones, the carbonyl group is found ________ in the carbon chain.

Answer 42

in the middle

Question 43

What is the name ending for ketones?

Answer 43

–one

Question 44

What is the carbonyl functional group sequence for ketones?

Answer 44

—COC—

Question 45

Name an oxidising agent that can distinguish between aldehydes and ketones.

Answer 45

Fehling's solution

Question 46

What color precipitate forms when Fehling's solution reacts with an aldehyde?

Answer 46

brick red

Question 47

What color change occurs with Tollens' reagent when reacting with aldehydes?

Answer 47

colourless to silver mirror

Question 48

What is the oxidation result of ketones when using Fehling's solution?

Answer 48

no reaction

Question 49

In summary, what happens with acidified dichromate solution when an aldehyde is present?

Answer 49

orange turns green

Question 50

What type of alcohol can be oxidised to produce 2-methylpropanal?

Answer 50

Primary

Question 51

What is the color change observed when acidified dichromate is used to oxidise an alcohol?

Answer 51

orange to green

Question 52

What colour change is observed when 2-methylpropan-1-ol is oxidised with acidified dichromate solution?

Answer 52

Orange to green

Question 53

What colour change occurs when 2-methylpropan-1-ol is oxidised with hot copper(II) oxide?

Answer 53

Black to brown

Question 54

What are sulphites commonly found in?

Answer 54

Wine and beer

Question 55

What do sulphites help prevent in alcoholic drinks?

Answer 55

Oxidation of ethanol

Question 56

Write the ion-electron equation for the oxidation of sulphite ions, SO3^2-.

Answer 56

SO3^2-(aq) + H2O(ℓ) → SO4^2-(aq) + 2H+(aq) + 2e-

Question 57

Name two substances produced if ethanol in alcoholic drinks were to be oxidised instead of sulphites.

Answer 57

Ethanal and ethanoic acid

Question 58

Why does the oxidation of propan-2-ol only result in the formation of one product?

Answer 58

It can only be oxidised to propanone (a ketone)

Question 59

Which property decreases in ketones as the carbon chain length increases?

Answer 59

Solubility in water

Question 60

Identify the functional group represented by the carbonyl group.

Answer 60

Carbonyl group

Question 61

What is the name of the molecule with the molecular formula C6H12O2?

Answer 61

Hexanoic acid

Question 62

What is the product formed first when propan-2-ol is oxidised?

Answer 62

Ethanal

Question 63

What type of reaction is represented by the term 'reduction'?

Answer 63

Reaction 3

Question 64

What is the structural feature of the compound where a Br atom is bonded to a carbon atom that is also bonded to two other carbon atoms?

Answer 64

Br atom bonded to a carbon atom with two other carbon atoms