Fuels and Other compounds: MCQ 5

15 Questions

What is the functional group present in aldehydes?

CHO

What is the purpose of the safety tube in the steam distillation apparatus?

To prevent a buildup of pressure and potential explosion

Why do short-chained aldehydes have higher boiling points than comparable alkanes?

Due to dipole-dipole interactions between molecules

What is the name of the compound extracted from cloves using steam distillation?

Eugenol

What is the reason for the solubility of short-chained aldehydes in water?

Due to the formation of hydrogen bonds between water and aldehyde molecules

What is the purpose of the Liebeg condenser in the steam distillation apparatus?

To condense the steam and mixture

What is a common use of ketones?

As a solvent

What happens to the polarity of longer-chained aldehydes?

It decreases

What is the purpose of adding an organic solvent, such as cyclohexane, to the emulsion?

To separate the eugenol from the water

What happens to the cyclohexane after it is used to separate the eugenol from the water?

It is evaporated off, leaving the pure eugenol behind

What is a characteristic of lower carboxylic acids?

They are liquids at room temperature with a sharp acidic smell.

What is the functional group present in all esters?

Carbonyl group

What is the main component of vinegar?

Ethanoic acid

What is the purpose of steam distillation in organic natural compounds?

To extract natural products from plant material.

What is a characteristic of aromatic compounds?

They are non-polar and soluble in cyclohexane.

Study Notes

Aldehydes

Contain the functional group CHO and end in "al"
Examples: Methanal (HCHO), Butanal (CH₃CH₂CH₂CHO)
Molecular formulas end in CHO
Short-chained aldehydes are polar due to the C=O bond, leading to higher boiling points and solubility in water
Longer chained aldehydes become less polar and are soluble in cyclohexane

Uses of Aldehydes

Found in nature (e.g., Benzaldehyde in almond kernels)
Produced when the body breaks down alcohol
Used in cooking as almond essence

Ketones

Contain the functional group C=O and end in "-one"
Examples: Propanone (Acetone), Butanone
Properties similar to aldehydes due to the carbonyl group
Liquids at room temperature, with lower ketones soluble in water and longer ketones soluble in cyclohexane
Uses: often found in nature (e.g., Testosterone, Progesterone), used as solvents (e.g., Propanone as a nail varnish remover)

Carboxylic Acids

Contain the carboxyl group and end in "-oic acid"
Examples: Methanoic acid (HCOOH), Butanoic acid (CH₃CH₂CH₂COOH)
Molecular formulas end in COOH
Lower carboxylic acids are liquids at room temperature with a sharp acidic smell
Higher carboxylic acids become less polar and are soluble in cyclohexane
Soluble in water due to hydrogen bonding

Uses of Carboxylic Acids

Used in food preservation (e.g., Propanoic acid)
Main component of vinegar (Ethanoic acid)
Emitted by nettles and ants (Methanoic acid)

Esters

Contain the functional group COO and end in "-oate"
Examples: Methyl ethanoate, Methyl propanoate
Made by combining carboxylic acids and alcohols
Properties similar to aldehydes and ketones
Esters with up to 5 carbons are water-soluble, while longer esters are soluble in cyclohexane

Uses of Esters

Have strong, pleasant, fruity smells (e.g., bananas, pears, mangos)
Used as solvents (e.g., Ethyl ethanoate)
Fats are naturally occurring esters made from long-chained carboxylic acids

Aromatic Compounds

Contain a benzene ring with delocalized double bonds
Non-polar and soluble in cyclohexane
Examples: Methylbenzene, Phenolphthalein, Aspirin
Uses: pharmaceuticals, insecticides, and indicators

Organic Natural Compounds

Found in nature (e.g., caffeine, nicotine, cocaine, aspirin)
Extracted using steam distillation
Steam distillation: a separation technique used to extract natural products from plant material
Example: Clove oil extraction using steam distillation