Alcohols

Alcohols are the organic compounds containing the –OH group. They are regarded as derivatives of alkanes. The names of alcohols are obtained by replacing the ‘e’ of the alkene with ‘ol’. Ethyl alcohol or Ethanol is the most important of all the alcohols. It is a second member of aliphatic alcohol series. Its common name is grain alcohol or drinking alcohol. It is a clear, colourless liquid with pleasant smell. Ethanol can be prepared in laboratory by the hydrolysis of alkyl halides. In industry, it is prepared either by the hydration of an alkene or by fermentation. Ethanol is a colourless, inflammable liquid. It dissolves in water in all proportions. It has spirituous odor and burning taste. Ethanol and other alcohols are neutral to litmus. Alcohols burn readily in air to produce carbon dioxide and water vapours. Ethanol burns with a pale blue, non-luminous flame. Alcohols react with oxidizing agents like potassium dichromate and potassium permanganate in the presence of an acid. They react with acetic acid (and other organic acids) to form esters. It is called as esterification reaction. Alcohols get dehydrated on heating with concentrated sulphuric acid at 170 ºC. Ethyl alcohol that is 95% pure and is obtained by fractional distillation is called absolute alcohol. Methylated spirit or denatured alcohol is ethyl alcohol with 5% of methyl alcohol, a colured dye and some pyridine. Spurious alcohol is illicit liquor made by improper distillation. It contains large proportions of methanol in a mixture of alcohols. Ethanol is used in alcoholic drinks like whisky, wine and beer. It is also used as fuel.

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  • Q1

    Marks:1
    Answer:

    X= aq. KOH and Y= PCl3

    Explanation:

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  • Q2

    Ethyl alcohol kept in laboratories is referred to as denatured alcohol. This is because it contains

    Marks:1
    Answer:

    methyl alcohol, pyridine and a coloured dye.

    Explanation:

    Ethyl alcohol used in laboratories is mixed with some methyl alcohol (poisonous), pyridine and a coloured dye in order to make it unsuitable for drinking purpose. That’s why it is called denatured alcohol.

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  • Q3

    Marks:1
    Answer:

    Ethanoic acid

    Explanation:

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  • Q4

    Pick the name which is not another name of ethanol.

    Marks:1
    Answer:

    wood spirit

    Explanation:

    Wood spirit is the name given to methanol. Ethyl alcohol, drinking alcohol and grain alcohol are the other names given to ethanol.

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  • Q5

    Fermentation of sugar is used to obtain:

    Marks:1
    Answer:

    Ethanol.

    Explanation:

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