Home
Class 12
CHEMISTRY
The freezing point of a solution contain...

The freezing point of a solution containing 5g of benzoic acid `(M=122 g mol^(-1))` in 35g of benzene is depressed by 2.94 K. What is the percentage association of benzoic acid if it forms a dimer in solution. [`K_(f)` for benzene = 4.9 K kg `mol^(-1)` ]

Text Solution

Verified by Experts

Number of moles of benzoic acid `=(5)/(122)`
Molality of benzoic acid solution `= (5)/(122) xx (1000)/(35) =1.17`
Apply the relation
`Delta T_(f) =i K_(f) m`, where i is van.t Hofff factor
`2.94 K=ixx4.8 Kg mol^(-1) xx 1.17 mol kg^(-1)`,
or `i=(2.94)/(4.9 xx 1.17)" "....(i)`
`(C_(6) H_(5) COOH)_(2) to (C_(6) H_(5) COOH)_(2)`
Total number of moles `=1-x (x//2) =1 - (x//2)`
`i= (1-(x)/(2))/(1)" "...(ii)`
From (i) and (ii), we have
`1-(x)/(2) = (2.94)/(4.9 xx 1.17)=0.5128`
or `(x)/(2) =1-0.5128=0.4872` or `x=0.9744` or `97.44%`
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • CBSE EXAMINATION PAPER 2020 (CODE No.56/4/1)

    U-LIKE SERIES|Exercise SECTION -D|3 Videos

  • CBSE EXAMINATION PAPER 2020 (CODE No.56/4/1)

    U-LIKE SERIES|Exercise SECTION -B|7 Videos

  • CBSE EXAMINATION PAPER 2020

    U-LIKE SERIES|Exercise SECTION D|6 Videos

  • CHEMICAL KINETICS

    U-LIKE SERIES|Exercise SELF ASSESSMENT TEST (SECTION D)|1 Videos

Similar Questions

Explore conceptually related problems

Phenol associates in benzene to from dimer (C_(6)H_(5)OH)_(2) . The freezing point of a solution containing 5g of phenol in 250 g of benzene is lowered by 0.70^(@)C . Calculate the degree of association of phenol in benzene .( k_(f) for benzene = 5.12 Km^(-1) )

The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g of benzene is lowered by 0.45^@C . Calculate the degree of association of acetic acid in benzene. K_f(C_6H_6) = 5.12 K "mol"^(-1) kg

Knowledge Check

  • The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45^@C . The degree of association of acetic acid in benzene is (Assume acetic acid dimerises in benzene and K_f for benzene = 5.12 K kg "mol"^(-1) ) ?

    A
    `94.6%`
    B
    `54.9%`
    C
    `78.2%`
    D
    `100%`

  • The depression in freezing point of benzene is 0.45^(@)C when 0.2 g of acetic acid is added to 20 g of benzene. If acetic acid associates to form a dimer in benzene, the percentage association of acetic acid in benzene will be ( K_(f) for benzene =5.12K kg mol^(-1) )

    A
    `80.4%`
    B
    `74.6%`
    C
    `94.6%`
    D
    `64.6%`

  • The freezing point of benzene decreases by 0.45^(@)C when 0.2 g of acetic acid is added to 20 g of benzene. IF acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be (K_(f) "for benzene" = 5.12 K kg mol^(-1))

    A
    `64.6%`
    B
    `80/4%`
    C
    `74.6%`
    D
    `94.6%`

    • Similar Questions

    Explore conceptually related problems

    The freezing point of solution containing 0.2 g of acetic acid in 20.0 g of benzene is lowered by 0.45^(@)C . Calculate the degree of association of acetic acid in benzene. (K_(f)=5.12 K^(@) mol^(-1) kg^(-1))

    Phenol associaes in bensen to a certain extent to from a dimer. A solution containing 2.0xx10^(-2) kg of phenol in 1.0 kg of benzene has a greezing point decreased by 0.69 K. What is the degree of association of phenol ? ( K_(f) for benzene=5.12 K kg mol^(-1) ).

    The freezing point of a solution contaning 0.3 g of acetic acid in 43 g of benzene reduces by 0.3^(@) . Calculate the Van's Hoff factor "( K_(f) for benzene = 5.12 K kg mol^(-1) )"

    Phenol associates in benzene to a certain extent to form a dimer. A solution containing 20xx10^(-1) kg phenol in 1 kg of benzene has its freezing pint depressed by 0.69 K. Calculate the fraction of phenol that has dimerised. "K"_("f")" for benzene"=5.12" kg mol"^(-1)"k" .

    The freezing point of benzene decreases by 0.45^(@)C when 0.2 g of acetic acid is added to 20 g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be ( K_(f) for benzene = 5.12 K kg "mol"^(-1) )

    Home
    Profile