Chapter 22: Some Families of Organic Compounds

Question 1

Chloroalkane

Answer 1

A chloroalkane is a compound in which one or more of the hydrogen atoms in an alkane molecule have been replaced by chlorine atoms.

Question 2

Functional group

Answer 2

is an atom or group of atoms which is responsible for the characteristic properties of an organic compound or a series of organic compounds.

Question 3

Primary alcohol

Answer 3

A primary alcohol is one where the carbon atom joined to the -OH group is attached to only one other carbon atom. EG ethanol.

Question 4

Secondary alcohol

Answer 4

A secondary alcohol is one where the carbon atom joined to the -OH group is attached to two other carbon atoms. EG propan-2-ol.

Question 5

Tertiary alcohol

Answer 5

A tertiary alcohol is one where the carbon atom joined to the -OH group is attached to three other carbon atoms. EG 2-methylpropan-2-ol

Question 6

Uses of ethanol

Answer 6

1. Fuel
2. Solvent
3. Alcoholic drinks

Question 7

Uses of chloroalkanes

Answer 7

As a solvent; for removing oil and grease from machinery and the dry cleaning of clothes.

Question 8

Physical properties of chloroalkanes

Answer 8

1. They readily dissolve in non-polar solvents such as cyclohexane and methylbenzene.
2. Liquids at room temp.

Question 9

Functional group in alcohols

Answer 9

-OH group (hydroxyl group)

Question 10

General formula of alcohols

Answer 10

Cn H2n+1 OH

Question 11

Physical properties of alcohols

Answer 11

1. Boiling point; Alcohols have higher boiling points that the corresponding alkanes. The higher boiling points are due to the fact that the highly polar -OH group gives rise to hydrogen bonding between the alcohol molecules. Because of this hydrogen bonding, extra energy must be supplied to break these bonds.
2. Solubility in water; Methanol, ethanol and propan-1-ol are infinitely soluble in water because of hydrogen bonding between the alcohol molecule and water molecules.

Question 12

Why are chloroalkanes liquid at room temperature but the corresponding alkanes are gases?

Answer 12

The polarity of the carbon-chlorine bond gives rise to intermolecular forces.

Question 13

Fermentation

Answer 13

• Ethanol for alcoholic drinks is produced by fermentation.
• Fruits such as grapes contain glucose.
• When yeast is added glucose forms a solution of ethanol and carbon dioxide.
  C6H12O6——-} 2C2H5OH + 2CO2

Question 14

Why is methanol added to industrial alcohol ?

Answer 14

Methanol is added as a denaturing agent. It prevents people from drinking it. Mixture is then called methylated spirits.