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Explain why alcohols and ethers of compa...

Explain why alcohols and ethers of comparable molecular mass have different boiling points?

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Alcohols undergo intermolecular H-bonding and hence exist as associated moelcules. Ethers, on the other hand, do not have H atom on the O-atom and hence do not form H-bonds. As a result, ethers exist as dicrete molecules which are held only by weak dipole-dipole attractions. since lesser energy is required to break weak dipole-dipole attactions than to break H-bonds in associated molecules of alcohols, therefore, boiling points of alcohols are much higher than those of ethers of comparable molecular mass.
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Give plausible explanation for each of the following . (i) Why are amines less acidic than alcohols of comparable molecular masses ? (ii) Why have primary amines higher boiling points than tertiary amines. (iii) Why are aliphatic amines stronger bases than aromatic amines ?

Assertion: Alcohols have higher boiling points than ethers of comparable molecular masses. Reason: Alcohols and ethers are isomerism in nature.

Knowledge Check

  • Assertion: Alcohols have higher boiling points than ethers of comparable molecular masses. Reason: Alcohols and ethers are isomeric in nature.

    A
    If both assertion and reason are true, and reason is the true explanation of the assertion.
    B
    If both assertion and reason are true, but reason is not the true explanation o the assertion.
    C
    if assertion is true, but reason is false.
    D
    If both assertion and reason are false.

  • Assertion : Alcohols have higher boiling points than ethers of comparable moleucular masses. Reason : Alcohols and ethers are isomeric in nature.

    A
    Both A and B are true and R is the correct explanation of A.
    B
    A is true but R is False.
    C
    A is False but R is True.
    D
    Both A and R are false.

    • Similar Questions

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    Alcohols are phenols consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are chiefly due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. The boiling points of alcuhols and phenols increase with increase in the number of carbun atoms (increase in van der Waals forces). In alcohols, the builing points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area). The - OH group in alcohols and phenols is involved in intermolecular hydrogen bonding. It is interesting to note that boiling points of alcohols and phenols are higher in compariscn to other classes of compounds, namely hydrocarbons, ethers, haloalkanes and heloarenes of comparable molecular masses. For example, ethanol and propane have comparable molecular masses but their boiling points differ widely. The boiling point of methoxymethane is intermediate of the two boiling points. The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons. Why do branched alcohols show a smaller boiling points than straight chain alcohols ?

    Alcohols are phenols consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are chiefly due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. The boiling points of alcuhols and phenols increase with increase in the number of carbun atoms (increase in van der Waals forces). In alcohols, the builing points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area). The - OH group in alcohols and phenols is involved in intermolecular hydrogen bonding. It is interesting to note that boiling points of alcohols and phenols are higher in compariscn to other classes of compounds, namely hydrocarbons, ethers, haloalkanes and heloarenes of comparable molecular masses. For example, ethanol and propane have comparable molecular masses but their boiling points differ widely. The boiling point of methoxymethane is intermediate of the two boiling points. The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons. Out of ethanol and propan-1-ol, which has the higher boiling point ?

    Alcohols are phenols consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are chiefly due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. The boiling points of alcuhols and phenols increase with increase in the number of carbun atoms (increase in van der Waals forces). In alcohols, the builing points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area). The - OH group in alcohols and phenols is involved in intermolecular hydrogen bonding. It is interesting to note that boiling points of alcohols and phenols are higher in compariscn to other classes of compounds, namely hydrocarbons, ethers, haloalkanes and heloarenes of comparable molecular masses. For example, ethanol and propane have comparable molecular masses but their boiling points differ widely. The boiling point of methoxymethane is intermediate of the two boiling points. The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons. Arrange methoxymethane, ethanol and propane in increase order of their boiling points.

    Alcohols are phenols consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are chiefly due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. The boiling points of alcuhols and phenols increase with increase in the number of carbun atoms (increase in van der Waals forces). In alcohols, the builing points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area). The - OH group in alcohols and phenols is involved in intermolecular hydrogen bonding. It is interesting to note that boiling points of alcohols and phenols are higher in compariscn to other classes of compounds, namely hydrocarbons, ethers, haloalkanes and heloarenes of comparable molecular masses. For example, ethanol and propane have comparable molecular masses but their boiling points differ widely. The boiling point of methoxymethane is intermediate of the two boiling points. The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons. Which part in alcohols and phenols mainly determines their properties ?

    Alcohols are phenols consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are chiefly due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. The boiling points of alcuhols and phenols increase with increase in the number of carbun atoms (increase in van der Waals forces). In alcohols, the builing points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area). The - OH group in alcohols and phenols is involved in intermolecular hydrogen bonding. It is interesting to note that boiling points of alcohols and phenols are higher in compariscn to other classes of compounds, namely hydrocarbons, ethers, haloalkanes and heloarenes of comparable molecular masses. For example, ethanol and propane have comparable molecular masses but their boiling points differ widely. The boiling point of methoxymethane is intermediate of the two boiling points. The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is lacking in ethers and hydrocarbons. Which kind of hydrogen bonding is involved in alcohols ?

    Give plausible explanation for each of the following : (i) Why are amines less acidic than alcohols of comparable molecular masses ? (ii). Why do primary amines have higher boiling poings han tertiary amines ? iii. Why are aliphatic amines stroner bases than aromatic amines ?

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