Alcohols 2.6 Flashcards
(42 cards)
What are alcohols?
Alcohols are a family of saturated aliphatic compounds in which one hydrogen atom has been replaced by an -OH group.
What is the -OH group in alcohols called?
The -OH group is known as the hydroxyl group and is the alcohol functional group.
What roles do alcohols perform in nature?
Alcohols occur widely in nature performing a variety of different roles.
What is the structure of a primary alcohol?
A primary alcohol has 1 carbon atom bonded to a carbon atom which is bonded to an OH group.
What is the structure of a secondary alcohol?
A secondary alcohol has 2 carbon atoms bonded to a carbon atom which is bonded to an OH group.
What is the structure of a tertiary alcohol?
A tertiary alcohol has 3 carbon atoms bonded to a carbon atom which is bonded to an OH group.
What is the boiling point comparison between alcohol and alkane?
The boiling point of a particular alcohol is higher than the corresponding alkane with the same number of carbon atoms.
What causes the higher boiling point of alcohols compared to alkanes?
This is due to the ability of an alcohol to exhibit hydrogen bonding, which is a stronger intermolecular force.
What are the intermolecular forces present in alcohols?
Alcohols exhibit hydrogen bonding in addition to van der Waals’ forces.
What is the miscibility of short chain alcohols with water?
Short chain alcohols are miscible with water as they can hydrogen bond with water molecules.
How does the miscibility of longer chain alcohols with water differ from short chain alcohols?
With longer chain alcohols, the ability to hydrogen bond is suppressed by the hydrophobic nature of the hydrocarbon chain.
What are miscible liquids?
Miscible liquids are liquids which mix in all proportions, i.e. form a single layer.
How is ethanol manufactured industrially?
Ethanol is manufactured by fermentation of plant carbohydrates such as starch using enzymes.
What is the process of breaking down starch into ethanol?
Starch is broken down into glucose by yeast under anaerobic conditions, which is then converted into ethanol and carbon dioxide.
C6H12O6 → 2C2H5OH + 2CO2
What method produces ethanol for alcoholic drinks?
Ethanol is produced via fermentation of grapes.
How are alcohols often produced in the laboratory?
Alcohols are produced via nucleophilic substitution of halogenoalkanes by aqueous alkali.
What are the benefits of using ethanol as a biofuel?
Ethanol is renewable and has high enthalpies of combustion.
What is the combustion reaction of ethanol?
The combustion of ethanol produces carbon dioxide and water.
2C2H5OH + 6O2 → 4CO2 + 6H2O
What is a carbon-neutral process?
A carbon-neutral process has no net annual carbon emissions to the atmosphere.
What are the main chemical processes involved in ethanol production?
- Photosynthesis in plants uses carbon dioxide to produce sugars.
- Fermentation produces ethanol and carbon dioxide from sugars.
- Combustion of ethanol produces carbon dioxide and water.
What is the overall equation when combining the three main processes of ethanol production?
The overall equation cancels out carbon dioxide on either side.
6CO2 → 6CO2
What makes alcohols reactive?
The C-O and O-H bonds in an alcohol are polar, allowing either bond to be broken.
How do alcohols behave during combustion?
Alcohols have high enthalpies of combustion; more carbon atoms result in a more orange and sooty flame.
With which substances do alcohols react?
Alcohols react with sodium, hydrogen bromide, and phosphorus pentachloride.
