Alcohol

Alcohols

What are alcohols?

• Alcohols are a homologous series of organic compounds with the general formula C_nH_2n+1OH and names ending –ol.

• The functional group in alcohols is the hydroxyl group: –OH.

Naming alcohols

Naming alcohols

• Alcohols with three or more carbon atoms display positional isomerism. The number of the carbon to which the hydroxyl groups is attached is written before the –ol.

Multiple Choice

What is the general formula of alcohols?

• C_nH_2nOH

• C_nH_2n+1

• C_nH_2n+1OH

• C_nH_2n+2OH

Multiple Choice

What is the chemical formula of an eight-carbon atom alcohol?

• C₈H₁₆OH

• C₈H₁₇OH

• C₈H₁₈OH

• C₈H₁₉OH

Multiple Choice

What is the name of the alcohol?

• propanal

• ethanol

• propanol

• ethanal

Multiple Choice

How many positional isomers does a five-carbon atom alcohol has?

• 1

• 2

• 3

• 4

Alcohols and hydrogen bonding

• The presence of the hydroxyl group with its electronegative oxygen atom means that alcohols are polar. They can therefore take part in hydrogen bonding.

• Hydrogen bonding between alcohol molecules means that an alcohol’s boiling point is higher than that of an alkane of similar molecular mass.

Alcohols and hydrogen bonding

• For example, methanol (Mr = 32) boils at 64.7 °C but ethane (Mr = 30) boils at -88.6 °C.

• Alcohols can mix with water because their molecules can form hydrogen bonds with water molecules.

Making wine and cider

• Alcohol has been produced by fermentation of sugars for thousands of years.

• Sugar from fruit or grains such as wheat and barley is mixed with yeast and water, which produces ethanol and other compounds.

Industrial fermentation

• Industrially, sugar cane, molasses (a product of refining sugar cane) or starch (from potatoes or corn) can be used for fermentation.

• The product is a mixture of water and about 15% ethanol by volume.

• No more alcohol is produced because the yeast is denatured by the alcohol.

Industrial fermentation

• Distillation can be used to remove most of the water from the ethanol.

Multiple Choice

What makes alcohols polar compounds?

• the presence of hydrogen atoms

• the presence of hydroxyl group

• the presence of oxygen atoms

• the presence of the alkyl group

Multiple Choice

What is the intermolecular force between alcohol molecules?

• London dispersion

• Van der Waals force

• Hydrogen bond

• Covalent bond

Multiple Choice

What makes alcohols to have higher boiling points compared to alkanes with the same molecular mass?

• The presence of hydrogen atoms

• The presence of the alkyl group

• The presence of hydrogen bonding

• The strong covalent bonds

Multiple Choice

What process produces alcohols from sugars?

• Alcoholization

• Fermentation

• Distillation

• Sugarization

Multiple Choice

What is the process used to separate water from alcohol?

• Fermentation

• Alcoholization

• Fractional distillation

• Distillation

Open Ended

Explain why there is only a maximum of 15% alcohol by volume produced in fermentation.

Production of ethanol from ethene

Multiple Choice

What process is used to make ethanol from ethene?

• Dehydration

• Electrophilic addition

• Hydration

• Nucleophilic substitution

Multiple Choice

Which condition is NOT needed for the formation of ethanol from ethene?

• 60 atm

• catalyst

• 70 MPa

• 297 ^oC

Multiple Choice

What is the catalyst used in the conversion of ethene to ethanol?

• Nickel

• Iron

• Phosphoric (V) acid

• Platinum

Multiple Choice

Which acts as an electrophile?

• One of the hydrogen atoms in phosphoric (V) acid

• One of the carbon atoms in ethene

• One of the carbon atoms in ethanol

• Phosphorus atom in the

Multiple Choice

What is formed after one hydrogen atom is bonded with one of the carbon atoms in ethene?

• alcohol

• carbocation

• electrophile

• nucleophile

Multiple Choice

What is the role of the water molecule in the process of ethanol formation from ethene?

• Acts as nucleophile

• Acts as electrophile

• Donates hydrogen atom

• Donates oxygen atom

Open Ended

Explain how phosphoric (V) acid is regenerate in the hydration of ethene?

Poll

I am confident that I have understood the lesson today.

• Strongly agree

• Agree

• Neither agree or disagree

• Disagree

• Strongly disagree