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An alcohol (A) gives Lucas test within 5...

An alcohol (A) gives Lucas test within 5 min. 7.4 g of alcohol when treated with sodium metal liberates 1120 mL of `H_2` at STP. What will be alcohol (A)?

A

`CH_(CH_2)_3OH`

B

`CH_3CH(OH)CH_2CH_3`

C

`(CH_3)_3OH`

D

`CH_3CH(OH) CH_2CH_2CH_3`

Text Solution

Verified by Experts

The correct Answer is:
B
`ROH+Na rarr RONa+1//2H_(2)uarr`
We have to get molecular mass of alcohol corresponding to half mole of `H_(2)` only.
No .of moles of `H_(2)` =No.of moles of alcohol
`1120/11200=7.4/(MM) rArr MM=74`
`C_(n)H_(2n+1) OH=rarr C_(n)H_(2n+1)=74-17=57`
`rArr C_(n)H_(2n)=57-1=56``i.e.12n+2n=14n=56`
`rArr n=56//14=14` Thus molecular formula of (A) is `C_(4)H_(9)OH`. As (A) gives Lucas test within 5 min, thus `2^@`alcohol corresponding to molecular formula `C_(4)H_(9)OH` is `CH_(3)CH(OH)CH_(2)CH_(3)` (butan -2-ol).
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Knowledge Check

  • 23 g of sodium will react with methyl alcohol to give :

    A
    one mole of oxygen
    B
    `22.4 "dm"^3` of hydrogen gas at NTP
    C
    1 mole of `H_2`
    D
    11.2 L of hydrogen gas at NTP

  • Which of the following gives two isomers of 3^(@) alcohol, when treated with phenyl magnesium bromide ?

    A
    B
    C
    D

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    A
    74
    B
    88
    C
    60
    D
    102