alcohols

Question 1

What functional group do alcohols have?

Answer 1

-OH (hydroxyl group)

Alcohols contain the hydroxyl functional group, which defines their chemical properties.

Question 2

What is a primary alcohol?

Answer 2

An alcohol where the hydroxyl group is attached to a carbon that is only connected to one other carbon

Example: Butan-1-ol.

Question 3

What is a secondary alcohol?

Answer 3

An alcohol where the hydroxyl group is attached to a carbon that is connected to two other carbons

Example: Butan-2-ol.

Question 4

What is a tertiary alcohol?

Answer 4

An alcohol where the hydroxyl group is attached to a carbon that is connected to three other carbons

Example: 2-methylpropane-2-ol.

Question 5

What is the general formula for alcohols?

Answer 5

C_nH_(2n+1)OH

This formula indicates the structure of alcohols based on the number of carbon atoms.

Question 6

What is the bond angle of the C-O-H in alcohols?

Answer 6

105°

This angle contributes to the molecular geometry of alcohols.

Question 7

What type of molecule is alcohol considered?

Answer 7

A polar molecule

The polarity affects its solubility and interactions with other substances.

Question 8

What happens when alcohols undergo dehydration?

Answer 8

They produce alkenes

This process can be done sustainably using alcohols made from fermentation of glucose.

Question 9

What is the primary source of alkenes when using alcohols from fermentation?

Answer 9

Plants

This method is considered more sustainable compared to using crude oil.

Question 10

What is the role of acid catalysts in the dehydration of alcohols?

Answer 10

They facilitate the elimination of water to form alkenes

Common acid catalysts include H2SO4 (sulfuric acid) and H3PO4 (phosphoric acid).

Question 11

True or False: Longer alcohol chains are more soluble in water.

Answer 11

False

As the carbon chain length increases, the solubility in water decreases.

Question 12

What are alkenes primarily used to make?

Answer 12

Polymers (plastics)

Alkenes are a key raw material in the production of various plastics.

Question 13

What is the primary method used for the dehydration of alkenes?

Answer 13

Distillation

Distillation is used to separate chemicals based on their boiling points.

Question 14

What is the result of dehydrating alkenes?

Answer 14

Impure product

The dehydration of alkenes often leads to the formation of impure products.

Question 15

Which chemical is used in the distillation process of cyclohexanol?

Answer 15

Concentrated H2SO4 and H3PO4

These acids are added to facilitate the dehydration process.

Question 16

What temperature should be maintained while heating the reactants in the distillation of cyclohexanol?

Answer 16

83°C

This is the boiling point of cyclohexanol.

Question 17

What happens to chemicals with boiling points less than 83°C during distillation?

Answer 17

They evaporate and enter the condenser

These chemicals cool down and condense back into liquid form.

Question 18

Why should a Bunsen burner not be used in this distillation process?

Answer 18

It is flammable

Safety concerns dictate avoiding open flames in this setup.

Question 19

What is the purpose of adding anti-bumping granules to the distillation flask?

Answer 19

To allow a smooth boiling process

Anti-bumping granules help prevent sudden boiling and bumps.

Question 20

What is the first step in the purification of cyclohexene after distillation?

Answer 20

Separation using a separating funnel

This step involves adding water to dissolve soluble impurities.

Question 21

What forms after the solution settles in the separating funnel?

Answer 21

Layers will form

The top layer contains impure cyclohexene, and the bottom layer contains water soluble impurities.

Question 22

What is collected after the separation process?

Answer 22

Impure cyclohexene

The top layer from the separation funnel is collected for further purification.

Question 23

Fill in the blank: The distillation process separates chemicals based on their _______.

Answer 23

boiling points

Question 24

What is the main impurity in the collected cyclohexene product?

Answer 24

Water soluble impurities

These impurities are removed in the separation step.

Question 25

What is the first step in the purification process of cyclohexane?

Answer 25

Take the impure cyclohexane from step 2 and add it to a round bottomed flask. ## Footnote The process aims to remove impurities from the cyclohexane.

Question 26

What is added to the round bottomed flask to act as a dehydrating agent?

Answer 26

Anhydrous calcium sulfate. ## Footnote This agent helps to remove any remaining water.

Question 27

How long should the flask be inverted for during the purification process?

Answer 27

20-30 minutes. ## Footnote This time allows water to be absorbed effectively.

Question 28

What indicates that water has been removed from the sample?

Answer 28

Keep adding calcium sulfate until it doesn't clump. ## Footnote Clumping indicates the presence of water.

Question 29

What is the raw material used for the production of ethanol?

Answer 29

Crude oil. ## Footnote Crude oil is a non-renewable resource.

Question 30

What type of process is used for producing ethanol?

Answer 30

Continuous process. ## Footnote This allows for a rapid reaction rate.

Question 31

What is the purity level of ethanol produced?

Answer 31

Very pure. ## Footnote High purity is essential for various applications.

Question 32

What is one of the labor costs associated with ethanol production?

Answer 32

Longer labor cost. ## Footnote This can impact the overall production expenses.

Question 33

What process produces alcohols from alkenes?

Answer 33

Hydration of alkenes. ## Footnote This is a chemical reaction involving water.

Question 34

What is the catalyst used in the hydration of alkenes?

Answer 34

Concentrated H3PO4. ## Footnote This acid catalyst facilitates the reaction.

Question 35

What are the conditions for the hydration reaction in terms of temperature?

Answer 35

300 °C. ## Footnote The temperature is critical for the reaction efficiency.

Question 36

What is the pressure condition for the hydration of alkenes?

Answer 36

70 atmospheres. ## Footnote High pressure is necessary to drive the reaction forward.

Question 37

Fill in the blank: Ethanol can be produced from steam and _______.

Answer 37

C2H4. ## Footnote Ethylene (C2H4) is the alkene used in this process.

Question 38

What is the process of making ethanol via fermentation using glucose from plants called?

Answer 38

Fermentation

Question 39

What is the chemical equation for the fermentation of glucose?

Answer 39

glucose → 2C2H5OH + 2CO2

Question 40

What organism is primarily used in the fermentation process?

Answer 40

Yeast

Question 41

What type of conditions does fermentation occur under?

Answer 41

Anaerobic conditions

Question 42

What is the role of enzymes in fermentation?

Answer 42

Catalyst that converts glucose into ethanol and carbon dioxide

Question 43

What is the optimum temperature for the enzymes involved in fermentation?

Answer 43

35°C

Question 44

What method is used to obtain pure ethanol after fermentation?

Answer 44

Fractional distillation

Question 45

What are some raw materials used for fermentation?

Answer 45

* Sugar cane * Sugar beet * Corn * Rice * Maize

Question 46

What type of process is fermentation considered?

Answer 46

Exothermic process

Question 47

What are the advantages of biofuels compared to crude oil?

Answer 47

* Renewable * More sustainable * Carbon neutral

Question 48

What is a disadvantage of converting existing petrol engines to use biofuels?

Answer 48

Expensive conversion costs

Question 49

What is one consequence of growing crops for biofuels?

Answer 49

Land for food is taken to grow fuel, leading to food shortages

Question 50

What is a significant environmental concern regarding biofuel production?

Answer 50

Fossil fuels are still used throughout the biofuel production chain

Question 51

What is the overall carbon neutrality equation for glucose during fermentation?

Answer 51

6CO2 + 6H2O → C6H12O6

Question 52

What is the equation for the production of ethanol from glucose?

Answer 52

C6H12O6 → 2C2H5OH + 2CO2

Question 53

What is the equation for burning ethanol to produce energy?

Answer 53

2C2H5OH + 6O2 → 4CO2 + 6H2O

Question 54

Fill in the blank: Fermentation is a _______ process that converts glucose into ethanol.

Answer 54

biochemical

Question 55

What can alconos be oxidised to?

Answer 55

Aldehydes, ketones, and carboxylic acids ## Footnote Alconos undergo oxidation to form these compounds.

Question 56

What is the oxidising agent used for oxidising alconos?

Answer 56

Acidified potassium dichromate (K2Cr2O7) ## Footnote This agent changes from orange (Cr2O7^2-) to green (Cr^3+).

Question 57

Which type of alconos cannot be oxidised using dichromate?

Answer 57

Tertiary alconos ## Footnote Only primary and secondary alconos can be oxidised.

Question 58

What is used in the oxidation of alconos?

Answer 58

Distillation and reflux ## Footnote These techniques help in controlling the reaction and the products formed.

Question 59

What happens to primary alconos during oxidation?

Answer 59

They are oxidised to aldehydes and then to carboxylic acids ## Footnote This reflects the stepwise oxidation process.

Question 60

What is the functional group present in aldehydes?

Answer 60

C=O and C-H ## Footnote Aldehydes have a carbonyl group at the end of the carbon chain.

Question 61

What type of alconos are oxidised into ketones?

Answer 61

Secondary alconos ## Footnote Ketones have a carbonyl group on an inner carbon.

Question 62

What should be done to remove the aldehyde from the oxidising agent?

Answer 62

Remove it when it forms strain to prevent further reaction ## Footnote This helps avoid conversion to carboxylic acids.

Question 63

What is the boiling point relationship between aldehydes and alconos?

Answer 63

Aldehydes have a lower boiling point than alconos ## Footnote This property aids in their separation during distillation.

Question 64

What conditions are used to make carboxylic acids from alconos?

Answer 64

Reflux and excess oxidising agent ## Footnote Reflux allows for strong heating while retaining volatile reactants and products.

Question 65

What happens to aldehydes during reflux?

Answer 65

They evaporate, condense, and fall back into the flask ## Footnote This ensures that the reaction continues effectively.

Question 66

What are secondary alcohols oxidised to?

Answer 66

Ketones ## Footnote Secondary alcohols undergo oxidation to form ketones.

Question 67

What is the reagent used in reflux to make ketones?

Answer 67

[O] ## Footnote The oxidation process involves the addition of oxidizing agents.

Question 68

What does K2Cr2O7 oxidise propan-2-ol to?

Answer 68

Propanone ## Footnote K2Cr2O7 is a strong oxidizing agent used in organic chemistry.

Question 69

Which solutions can distinguish between aldehydes and ketones?

Answer 69

Fehling's solution and Tollens' reagent ## Footnote These are both oxidizing agents that react differently with aldehydes and ketones.

Question 70

True or False: Fehling's solution oxidises ketones.

Answer 70

False ## Footnote Fehling's solution oxidises aldehydes but not ketones.

Question 71

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

Answer 71

Brick red precipitate (Cu2O) ## Footnote This indicates the presence of aldehydes in the solution.

Question 72

What happens when Tollens' reagent is added to aldehydes?

Answer 72

Silver coats the inside of the flask ## Footnote This reduction indicates the presence of aldehydes.

Question 73

What is the result of adding Tollens' reagent to ketones?

Answer 73

No silver precipitate formed ## Footnote Ketones do not reduce Tollens' reagent.

Question 74

Fill in the blank: Secondary alcohols are oxidised to _______.

Answer 74

ketones

Question 75

What is a common characteristic of aldehydes in reactions with oxidising agents?

Answer 75

They are oxidised to carboxylic acids ## Footnote Aldehydes can be further oxidised to form carboxylic acids.