Fuels and Other compounds: MCQ 5
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Questions and Answers

What is the functional group present in aldehydes?

  • OH
  • CO
  • CHO (correct)
  • COH

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

  • To collect condensed steam
  • To separate the eugenol from the water
  • To add organic solvents to the mixture
  • To prevent a buildup of pressure and potential explosion (correct)

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

  • Due to Van der Waals forces between molecules
  • Due to their non-polar nature
  • Due to dipole-dipole interactions between molecules (correct)
  • Due to hydrogen bonding between molecules

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

    <p>Eugenol</p> Signup and view all the answers

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

    <p>Due to the formation of hydrogen bonds between water and aldehyde molecules</p> Signup and view all the answers

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

    <p>To condense the steam and mixture</p> Signup and view all the answers

    What is a common use of ketones?

    <p>As a solvent</p> Signup and view all the answers

    What happens to the polarity of longer-chained aldehydes?

    <p>It decreases</p> Signup and view all the answers

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

    <p>To separate the eugenol from the water</p> Signup and view all the answers

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

    <p>It is evaporated off, leaving the pure eugenol behind</p> Signup and view all the answers

    What is a characteristic of lower carboxylic acids?

    <p>They are liquids at room temperature with a sharp acidic smell.</p> Signup and view all the answers

    What is the functional group present in all esters?

    <p>Carbonyl group</p> Signup and view all the answers

    What is the main component of vinegar?

    <p>Ethanoic acid</p> Signup and view all the answers

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

    <p>To extract natural products from plant material.</p> Signup and view all the answers

    What is a characteristic of aromatic compounds?

    <p>They are non-polar and soluble in cyclohexane.</p> Signup and view all the answers

    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

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    Description

    Learn about the structure and properties of aldehydes, including their functional group, molecular formulas, and solubility and boiling points.

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