What are alcohols?
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What are alcohols?
Alcohols are colorless liquids that dissolve in water to form neutral solutions.
What are the first four alcohols commonly used for?
The first four alcohols are commonly used as fuels. Methanol and ethanol are also used extensively as solvents.
Why are methanol and ethanol good solvents?
Methanol and ethanol can dissolve many substances that water cannot, such as fats and oils, but can also dissolve most substances that water can dissolve.
How are alcohols named?
Alcohols are named using the same system as alkanes and alkenes, with the final 'e' being replaced with 'ol'.
Give the name and formula of the first alcohol.
The name and formula of the first alcohol is methanol, CH3OH.
Define the term alcohol.
An organic compound containing a hydroxyl (-OH) group attached to a carbon atom.
Define the term functional group.
A functional group is the specific group of atoms responsible for the characteristic chemical reactions of a compound.
Define the term hydroxyl group.
A hydroxyl group is the functional group -OH, consisting of an oxygen atom bonded to a hydrogen atom.
True or False?
It is standard practice to write the functional group at the end when naming alcohols.
True.
It is standard practice to write the functional group on the end when naming alcohols, e.g., CH3OH for methanol.
What are the three ways in which ethanol can undergo oxidation?
Three ways in which ethanol can undergo oxidation:
1) Combustion,
2) Aerobic oxidation,
3) Treatment with an oxidising agent.
What is the equation for the complete combustion of ethanol?
The equation for the complete combustion of ethanol is:
C2H5OH + 3O2 → 2CO2 + 3H2O
Explain what is meant by the aerobic oxidation of ethanol.
Bacteria in the air (acetobacter) use atmospheric oxygen to oxidise ethanol to ethanoic acid and water:
C2H5OH + O2 → CH3COOH + H2O
What happens when ethanol is treated with an oxidising agent like acidified potassium dichromate(VI)?
When ethanol is treated with an oxidising agent, ethanol undergoes oxidation to produce ethanoic acid:
CH3CH2OH + [O] → CH3COOH + H2O
What is observed during the oxidation of ethanol with potassium dichromate?
During the oxidation of ethanol with potassium dichromate, the potassium dichromate solution turns from orange to green during the reaction.
What is meant by the term oxidation?
A chemical reaction in which an element or compound loses electrons, increasing its oxidation state.
What is meant by the term combustion?
Combustion involves a chemical reaction in which a substance reacts with oxygen to release heat and light.
Explain the meaning of the term aerobic.
The term aerobic refers to a process or organism that requires the presence of oxygen.
State the meaning of oxidising agent.
An oxidising agent is a substance that has the ability to oxidise other substances by accepting electrons.
True or False?
Ethanol can be oxidised to produce ethanoic acid (vinegar).
True.
Ethanol can be oxidised to produce ethanoic acid, which is the main component of vinegar.
How can ethanol be synthesised industrially?
Ethanol can be synthesised by the hydration of ethene.
What are the conditions for the hydration of ethene to produce ethanol?
The conditions required for the hydration of ethene are a temperature of around 300°C, pressure of 60-70 atm, and a concentrated phosphoric acid catalyst.
How are ethanol and water separated from the reaction mixture after hydration?
Ethene is separated first due to its much lower boiling point, then ethanol and water are separated by fractional distillation.
What is the equation for the hydration of ethene to produce ethanol?
The equation for the hydration of ethene is:
CH2=CH2 + H2O → CH3CH2OH
How is ethanol produced by fermentation?
Ethanol is produced by fermentation through yeast enzymes breaking down sugar or starch in the absence of oxygen to produce ethanol and carbon dioxide:
C6H12O6 → 2CO2 + 2C2H5OH
State the meaning of hydration.
A chemical reaction in which a water molecule is added to a compound.
Define the term catalyst.
A substance that increases the rate of a chemical reaction without being consumed in the process.
Explain what is meant by the term fractional distillation.
A method of separating a mixture of liquids based on their different boiling points.
Explain what is meant by fermentation.
A process in which yeast or bacteria convert carbohydrates into alcohol or acids in the absence of oxygen.
True or False?
Fermentation is an aerobic process.
False.
Fermentation is an anaerobic process that does not require oxygen for ethanol to be produced.