alcohols

Question 1

what is the definition of biofuel?

Answer 1

a fuel produced from plants or other living matter

Question 2

what is the definition of carbon neutral?

Answer 2

an activity that has no net annual carbon emissions to the atmosphere

Question 3

what is the definition of oxidation?

Answer 3

loss of electrons, gain of oxygen, loss of hydrogen

Question 4

what is the definition of oxidising agent?

Answer 4

a substance which is reduced so another substance can be oxidised

Question 5

position isomer

Answer 5

structural isomers that differ by having the functional group in a different position

Question 6

what is the definition of reduction

Answer 6

gain of electrons, loss of oxygen, gain of hydrogen

Question 7

what is the definition of reducing agent

Answer 7

a substance which is oxidised so that another substance can be reduced

Question 8

what is the definition of reflux?

Answer 8

heating a reaction mixture while continually cooling the vapour produced back into the liquid form using a condenser

Question 9

what is stereoisomer?

Answer 9

molecules with the same molecular and structural formulae but a different spatial arrangement of atoms

Question 10

what is structural isomer

Answer 10

molecules with the same molecular formular but different structures

Question 11

what is the definition of unsaturated

Answer 11

molecule containing double bonds

Question 12

What is the general formula for alcohols?

Answer 12

CnH2n+1 OH

Question 13

How can the formula for alcohols be shortened?

Answer 13

ROH

Question 14

What is the first step in naming alcohols?

Answer 14

Identify the parent alkane

Question 15

What should you find when identifying the parent alkane?

Answer 15

The longest continuous carbon chain containing the hydroxyl group (-OH)

Question 16

What is the second step in naming alcohols?

Answer 16

Replace the ‘-e’ ending of the parent alkane name with ‘-ol’

Question 17

If the parent alkane is ‘propane’, what is the name of the corresponding alcohol?

Answer 17

Propanol

Question 18

What is the third step in naming alcohols?

Answer 18

Number the carbon atoms in the chain

Question 19

Why is it important to number the carbon atoms in the alcohol chain?

Answer 19

So that the hydroxyl group (-OH) has the lowest possible number

Question 20

What do alcohol groups have priority over in naming?

Answer 20

Carbonyl groups

Question 21

How do you indicate the position of the hydroxyl group in the alcohol name?

Answer 21

Use a number to indicate the position of the hydroxyl group

Question 22

If the hydroxyl group is on the second carbon, how would you name the alcohol?

Answer 22

Propan-2-ol

Question 23

What should you do if there are other substituents on the carbon chain?

Answer 23

Name them as usual and include their positions using numbers

Question 24

How should substituents be ordered in the naming of alcohols?

Answer 24

List substituents in alphabetical order

Question 25

What prefixes are used to indicate the number of hydroxyl groups in a compound?

Answer 25

Di, tri, tetra ## Footnote These prefixes indicate two, three, and four hydroxyl groups, respectively.

Question 26

What is the bond angle in alcohols?

Answer 26

105° ## Footnote This angle is due to the arrangement of bonding and lone pairs around the oxygen atom.

Question 27

Why is the bond angle in alcohols reduced from the ideal tetrahedral angle?

Answer 27

Lone pairs repel more than bonding pairs ## Footnote This leads to a position of minimum repulsion, resulting in a smaller bond angle.

Question 28

What defines a primary alcohol (1º)?

Answer 28

The carbon atom bonded to the -OH group is attached to one other carbon atom ## Footnote Primary alcohols have the general formula R-CH2OH.

Question 29

How is a secondary alcohol (2º) characterized?

Answer 29

The carbon atom bonded to the -OH group is attached to two other carbon atoms ## Footnote Secondary alcohols have the general formula R-CHOH-R'.

Question 30

What distinguishes a tertiary alcohol (3º)?

Answer 30

The carbon atom bonded to the -OH group is attached to three other carbon atoms ## Footnote Tertiary alcohols have the general formula R-COH(R')2.

Question 31

What type of molecules are alcohols?

Answer 31

Polar molecules ## Footnote Alcohols have a -OH group which contributes to their polarity.

Question 32

What causes the partial positive charge in alcohols?

Answer 32

The highly electronegative O atom in the -OH group pulls electron density away from adjacent H and C atoms ## Footnote This results in a polar bond.

Question 33

What type of bonds can form between alcohol molecules?

Answer 33

Hydrogen bonds ## Footnote These bonds lead to higher melting and boiling points compared to alkanes.

Question 34

How does the presence of the alcohol group affect solubility in water?

Answer 34

It makes short-chain alcohols like methanol and ethanol soluble in water ## Footnote The ability to form hydrogen bonds with water contributes to this solubility.

Question 35

What interactions do alkyl chains form?

Answer 35

Weak instantaneous temporary dipole-dipole interactions ## Footnote Alkyl chains are non-polar and do not form hydrogen bonds.

Question 36

What happens to the effects of the alcohol group as the chain length increases?

Answer 36

The unique effects of the alcohol group become less prominent ## Footnote Longer carbon chains lead to decreased solubility in water.

Question 37

What is the state of ethane at room temperature?

Answer 37

Gas ## Footnote Ethane cannot form hydrogen bonds like ethanol.

Question 38

What is the state of ethanol at room temperature?

Answer 38

Liquid ## Footnote Ethanol forms hydrogen bonds which require more energy to overcome.

Question 39

What type of interactions exist in ethane compared to ethanol?

Answer 39

Instantaneous temporary dipole-dipole interactions ## Footnote These are weaker than hydrogen bonds in ethanol.

Question 40

Why does ethanol have a higher boiling point than ethane?

Answer 40

Ethanol requires more energy to overcome hydrogen bonds ## Footnote Higher thermal energy is needed due to stronger intermolecular forces.

Question 41

Fill in the blank: Alcohols form _______ with other alcohol molecules.

Answer 41

Hydrogen bonds

Question 42

What do alcohols produce when they undergo complete combustion?

Answer 42

Carbon dioxide and water ## Footnote The reaction is represented as: alcohol + oxygen → carbon dioxide + water.

Question 43

What type of flame do smaller alcohols burn with?

Answer 43

An almost invisible flame

Question 44

How can ethanol be produced sustainably?

Answer 44

By the fermentation of sugars

Question 45

What is the energy density of ethanol compared to petrol?

Answer 45

Lower than petrol

Question 46

What must cars running on ethanol have due to its lower energy density?

Answer 46

A larger fuel tank or fill up more often

Question 47

What is the benefit of blending ethanol with petrol or diesel?

Answer 47

Increases energy density and makes flames easier to see

Question 48

What socio-economic concern is associated with using large quantities of farmland for ethanol production?

Answer 48

It could be better used for food production

Question 49

Fill in the blank: Alcohols react with oxygen in the air when ignited and undergo complete combustion to form _______.

Answer 49

carbon dioxide and water

Question 50

True or False: The combustion of alcohols produces heat.

Answer 50

True

Question 51

What happens to alcohols during oxidation?

Answer 51

They can be oxidised to other products depending upon the type of the alcohol.

Question 52

What is an oxidising agent?

Answer 52

A substance that oxidises another.

Question 53

How is oxidation shown in an equation?

Answer 53

By using [O].

Question 54

What is a common oxidising agent used in oxidation reactions?

Answer 54

Acidified dichromate (VI) ions, H+/Cr2O7^2-.

Question 55

What is the typical form in which acidified dichromate (VI) ions are provided?

Answer 55

In the form of sulphuric acid mixed with potassium dichromate solution.

Question 56

What color are potassium dichromate (VI) ions?

Answer 56

Orange.

Question 57

To what color are dichromate (VI) ions reduced?

Answer 57

Green chromium (III) ions (Cr3+).

Question 58

What does the reduction of dichromate (VI) ions indicate?

Answer 58

They are acting as oxidising agents.

Question 59

What is the color of acidified potassium manganate(VII)?

Answer 59

Purple.

Question 60

What is required for the reduction of potassium manganate(VII) to take place?

Answer 60

An acidic medium.

Question 61

What happens to the purple manganate ions during alcohol oxidation?

Answer 61

They are reduced to colourless Mn^2+ ions.

Question 62

What can primary alcohols be oxidised to form?

Answer 62

Aldehydes ## Footnote Aldehydes can undergo further oxidation to form carboxylic acids.

Question 63

What do secondary alcohols oxidise to form?

Answer 63

Ketones only

Question 64

Do tertiary alcohols undergo oxidation?

Answer 64

No

Question 65

What is the first step in the oxidation of primary alcohols?

Answer 65

The primary alcohol is added to the oxidising agent and warmed

Question 66

What happens to the boiling points of aldehydes compared to primary alcohols?

Answer 66

The aldehyde product has a lower boiling point than the alcohol reactant

Question 67

What occurs if the aldehyde is not distilled off during oxidation?

Answer 67

Further refluxing with excess oxidising agent will oxidise it to a carboxylic acid

Question 68

What must be done with the ketone product after it has been formed?

Answer 68

It does not need to be distilled off straight away

Question 69

Fill in the blank: Tertiary alcohols do not undergo _______.

Answer 69

Oxidation

Question 70

True or False: Aldehydes can be further oxidised to form carboxylic acids.

Answer 70

True

Question 71

True or False: Secondary alcohols can be oxidised to form carboxylic acids directly.

Answer 71

False