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Chemistry Unit 2 > Alcohols > Flashcards

Alcohols Flashcards

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1
Q

What type of bonding allows alcohols to be soluble in water?

A

Hydrogen bonds

Alcohols form hydrogen bonds with water, unlike alkanes.

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2
Q

How does the solubility of alcohols in water change with the carbon chain length?

A

Decreases as the carbon chain increases

Only the first 3 alcohols are soluble in water.

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3
Q

What is the preparation method for alcohols from halogenoalkanes?

A

Alkaline hydrolysis

This involves the substitution of a halogen with a hydroxide ion.

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4
Q

What is the general equation for the alkaline hydrolysis of a bromoalkane?

A

RBr + OH → ROH + Br

R represents the hydrocarbon chain.

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5
Q

What is the product formed when 1-bromobutane reacts with aqueous sodium hydroxide?

A

Butan-1-ol

The reaction follows an SN2 mechanism.

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6
Q

What is the mechanism involved in the reaction of 1-bromobutane with hydroxide ion?

A

SN2

This is a nucleophilic substitution mechanism.

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7
Q

How can butan-2-ol be prepared?

A

By refluxing chlorobutane with aqueous sodium hydroxide

This involves a similar hydrolysis process.

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8
Q

What is the general equation for the alkaline hydrolysis of a chloroalkane?

A

RCI + OH → ROH + CI

R represents the hydrocarbon chain.

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9
Q

What does the term ‘steric hindrance’ refer to in the context of alcohol preparation?

A

Interference caused by larger groups that affect nucleophilic substitution

This can influence the reaction pathway and product formation.

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10
Q

Fill in the blank: Alcohols are prepared from the corresponding _______ by nucleophilic substitution.

A

halogenoalkanes

This includes bromoalkanes, chloroalkanes, and iodoalkanes.

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11
Q

True or False: The hydrocarbon chain of alcohols contributes to their solubility in water.

A

False

The hydrocarbon chain does not form hydrogen bonds.

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12
Q

What percentage of petrol can ethanol make up?

A

10%

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13
Q

What does the addition of ethanol to petrol do to its octane rating?

A

It gives it a higher octane rating

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14
Q

What are the products of complete combustion of alcohols in a plentiful supply of oxygen?

A

Carbon dioxide and water

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15
Q

What is formed when alcohols are burned in a limited supply of oxygen?

A

Carbon monoxide

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16
Q

Write the balanced combustion equation for ethanol.

A

C2H5OH + 3O2 → 2CO2 + 3H2O

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17
Q

What is the state symbol used to indicate a solution in alcohol?

A

(alc)

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18
Q

What type of bond does the O-H group in alcohols have?

A

It behaves like the O-H bonds in water

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19
Q

What is the reaction of sodium with water?

A

2H2O + 2Na → 2NaOH + H2

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20
Q

What is the reaction of sodium with ethanol?

A

2C2H5OH + 2Na → 2C2H5ONa + H2

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21
Q

What is sodium ethoxide?

A

The product formed from the reaction of sodium with ethanol

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22
Q

What is the nature of the reaction between sodium and ethanol?

A

Exothermic

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23
Q

What does sodium ethoxide react with to form a strongly alkaline solution?

A

Water

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24
Q

Fill in the blank: The reaction of sodium with ethanol produces _______.

A

Sodium ethoxide

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25
True or False: The combustion of alcohols only produces carbon dioxide.
False
26
What does the term halogenation refer to?
A reaction in which one or more halogen atoms add to a compound or replace atoms in the compound.
27
What is produced when an alcohol reacts with a hydrogen halide?
The corresponding halogenoalkane (RX) and water (H2O).
28
What is replaced in the alcohol during the halogenation process?
The hydroxyl (OH) group is replaced by a halogen (X).
29
What reagents can be used for halogenation of alcohols?
Different reagents can be used, including hydrogen halides.
30
Fill in the blank: The reaction of an alcohol (ROH) with a hydrogen halide (HX) produces _______.
halogenoalkane (RX)
31
True or False: Halogenation of alcohols only involves chlorine and bromine halides.
False
32
How is the hydrogen halide (HX) prepared for the reaction?
By reacting the corresponding sodium salt with concentrated sulfuric acid.
33
What is the general reaction formula for the halogenation of an alcohol?
ROH + HX → RX + H2O
34
What is produced when refluxing butan-2-ol, sodium bromide, and concentrated sulfuric acid?
The corresponding bromoalkane ## Footnote Specifically, this process produces 2-bromobutane from secondary butan-2-ol.
35
What is the chemical equation for the reaction of sodium bromide with concentrated sulfuric acid?
NaBr + H₂SO₄ → NaHSO₄ + HBr ## Footnote This reaction is part of the process that leads to the formation of bromoalkanes.
36
What type of alcohol is butan-2-ol?
Secondary ## Footnote Secondary alcohols have the hydroxyl group (-OH) attached to a carbon that is connected to two other carbons.
37
What is the role of steric hindrance in the reaction of butan-2-ol?
It affects the reactivity of the alcohol ## Footnote Steric hindrance occurs due to the size of the R groups, influencing nucleophilic substitution reactions.
38
What is phosphorus pentachloride's chemical formula?
PCl₅ ## Footnote Phosphorus pentachloride is a white solid used in chlorination reactions.
39
What type of reaction occurs when phosphorus pentachloride reacts with alcohols?
Chlorination ## Footnote This reaction produces chloroalkanes and is exothermic.
40
What is the product formed when phosphorus pentachloride reacts with propan-1-ol?
1-chloropropane ## Footnote The reaction also produces HCl gas and POCl₃.
41
What is the chemical equation for the reaction of propan-1-ol with phosphorus pentachloride?
C₃H₇OH + PCl₅ → C₃H₇Cl + HCl + POCl₃ ## Footnote This equation illustrates the conversion of alcohol to chloroalkane.
42
What type of gas is produced during the reaction of phosphorus pentachloride with alcohol?
HCl ## Footnote HCl is a colorless, pungent-smelling gas that is released during the reaction.
43
What safety precaution should be taken when reacting phosphorus pentachloride with alcohol?
Carry out the reaction in a fume cupboard ## Footnote This is necessary due to the release of HCl gas.
44
How can the presence of alcohol be tested using phosphorus pentachloride?
The HCl gas turns damp blue litmus paper red ## Footnote Additionally, it produces white fumes when contacting concentrated ammonia.
45
What solution is used to oxidise alcohols?
Acidified potassium dichromate solution ## Footnote This solution is a mixture of concentrated sulfuric acid (H₂SO₄) and potassium dichromate (K₂Cr₂O₇).
46
What color is the acidified potassium dichromate solution?
Orange ## Footnote The orange color is due to the Cr⁶⁺ ions in K₂Cr₂O₇.
47
What happens to the color of the solution when oxidation occurs?
Turns green ## Footnote The green solution is due to Cr³⁺ ions.
48
What types of alcohols can be oxidised?
Primary and secondary alcohols ## Footnote Tertiary alcohols cannot be oxidised.
49
What is the product when primary alcohols are oxidised?
Aldehyde ## Footnote This occurs when primary alcohols are gently heated with acidified potassium dichromate in excess alcohol.
50
What is the oxidation reaction for Cr⁶⁺ ions?
Cr⁶⁺ (aq) + 3e⁻ → Cr³⁺ (aq) ## Footnote This reaction illustrates the reduction of chromium ions during oxidation of alcohols.
51
Fill in the blank: Tertiary alcohols _______ be oxidised.
cannot ## Footnote This is a key distinction in the oxidation of alcohols.
52
What occurs during the gentle heating of primary alcohols with potassium dichromate?
Formation of aldehyde ## Footnote This reaction requires the presence of alcohol in excess.
53
What is formed at the end of the oxidation of propan-1-ol?
An aldehyde is formed ## Footnote Specifically, propanal is formed.
54
What happens to the OH group during the oxidation process?
The OH is removed with a hydrogen on that carbon, leaving a C=O ## Footnote This transformation is a key step in forming the aldehyde.
55
What is the oxidising agent used in the oxidation of propan-1-ol to propanal?
K2Cr2O7/H2SO4 ## Footnote This combination is commonly used in organic chemistry for oxidation reactions.
56
What is the purpose of distillation in the oxidation of propan-1-ol?
To distill off the aldehyde as it forms ## Footnote This prevents further oxidation of the aldehyde to a carboxylic acid.
57
What is the product when propan-1-ol is oxidised with excess oxidising agent?
Carboxylic acid ## Footnote Specifically, propanoic acid is formed when the reaction goes to completion.
58
Fill in the blank: The reaction of propan-1-ol with K2Cr2O7/H2SO4 under reflux conditions leads to the formation of _______.
Propanoic acid
59
What stage does propan-1-ol pass through during complete oxidation?
The aldehyde stage ## Footnote This refers to the intermediate formation of propanal before it is further oxidised to propanoic acid.
60
True or False: The aldehyde formed during the oxidation of propan-1-ol can be oxidised further.
True ## Footnote This is why it is distilled off immediately after formation.
61
What is the role of the cold water inlet in the distillation setup?
To cool the condenser ## Footnote This helps in condensing the vapors back into liquid form.
62
What is the function of the distilling flask in the oxidation process?
To contain the mixture for distillation ## Footnote This allows for the controlled heating and separation of components.
63
What is the purpose of a thermometer in distillation?
To measure the temperature of the boiling liquid.
64
What is the function of the water outlet in a distillation setup?
To remove water that has been used for cooling.
65
Fill in the blank: The _______ prevents volatile liquids from evaporating off during refluxing.
condenser
66
What is the role of refluxing in distillation?
To heat/boil volatile liquids for an extended period.
67
What does distillation do?
Evaporates and condenses liquids at different temperatures.
68
Fill in the blank: When collecting liquid in distillation, it should be around its _______.
boiling point
69
What happens to the aldehyde when making carboxylic acid?
It is oxidized during refluxing.
70
True or False: Secondary alcohols can be oxidized to form ketones.
True
71
What reagent is used to oxidize secondary alcohols?
Acidified potassium dichromate
72
What is formed when a secondary alcohol is oxidized?
A ketone
73
What is a carbonyl group?
A functional group characterized by a C=O bond.
74
Fill in the blank: In the oxidation of secondary alcohols, the OH is removed with a _______ on that carbon.
hydrogen
75
What type of compound is produced at the end of the oxidation of a secondary alcohol?
Ketone
76
What is the structure of Pentant 2-one?
H - C-C-C-C-C-H with a C=O group positioned on the second carbon.
77
What is the oxidation product of a primary alcohol?
Aldehyde → Carboxylic acid ## Footnote The reaction involves distillation with excess oxidizing agent.
78
What is the oxidation product of a secondary alcohol?
Ketone ## Footnote The reaction is carried out using reflux to ensure complete conversion.
79
What happens to tertiary alcohols during oxidation?
No reaction ## Footnote Tertiary alcohols cannot be oxidized due to the absence of a hydrogen atom on the carbon with the OH group.
80
What is the reagent used for oxidizing alcohols?
K2Cr2O7 / H2SO4 ## Footnote This is a common oxidizing agent used in alcohol oxidation reactions.
81
What is the role of heat in the oxidation of alcohols?
Facilitates the reaction ## Footnote Heat is used to ensure the reaction proceeds effectively.
82
What does [O] represent in alcohol oxidation?
Oxidizing agent ## Footnote It indicates the presence of an oxidizing agent in the reaction mechanism.
83
In the oxidation of butan-2-ol, what is the final product?
Butanone ## Footnote Butan-2-ol is oxidized to form butanone.
84
What is the structure of propanal?
CH3-CH2-CHO ## Footnote Propanal is the aldehyde formed from the oxidation of a primary alcohol.
85
What is the structure of propanoic acid?
CH3-CH2-COOH ## Footnote Propanoic acid is the carboxylic acid formed from the further oxidation of propanal.
86
What does reflux mean in the context of alcohol oxidation?
Heating with continuous condensation ## Footnote Reflux ensures that volatile components are condensed back into the reaction mixture.
87
Fill in the blank: Tertiary alcohols cannot be ______.
oxidised ## Footnote This is due to the lack of a hydrogen atom on the carbon with the OH group.
88
What is the general outcome when a primary alcohol is oxidized?
Conversion to carboxylic acid ## Footnote The process typically involves an aldehyde intermediate.

Chemistry Unit 2 (11 decks)

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