A certain mass of substance- when dissolved in 100 g C6H6- lowers the freezing point by 1-28-C- The same mass of solute dissolved in 100 g water lowers the freezing point by 1-40-C- If the substance has normal molecular weight in benzene and is completely ionized in water- into how many ions does it dissociate in water- Kf for H2O and C6H6O are 1-86 and 5-12 K kg mol-1-

The correct option is C 3 ions Δ T_f= iK_fm For benzene 1.28 = 1 × 5.12 ×x100 ⇒ x= 25 mol For water #160; 1.40= i × 1.86 ×25100 ...

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Byju's Answer

Standard XII

Chemistry

Depression in Freezing Point

A certain mas...

Question

A certain mass of substance, when dissolved in 100 g $C_{6} H_{6},$ lowers the freezing point by ${1.28}^{\circ} C .$ The same mass of solute dissolved in 100 g water lowers the freezing point by ${1.40}^{\circ} C .$ If the substance has normal molecular weight in benzene and is completely ionized in water, into how many ions does it dissociate in water? $K_{f}$ for $H_{2} O$ and $C_{6} H_{6} O$ are 1.86 and 5.12 K kg $m o l^{- 1} .$

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Solution

The correct option is C $3$ ions
$Δ T_{f} = i K_{f} m$

For benzene
$1.28 = 1 \times 5.12 \times \frac{x}{100}$
$\Rightarrow x = 25 m o l$

For water
$1.40 = i \times 1.86 \times \frac{25}{100}$
$\Rightarrow i = 3$

The substance dissociates into three ions in water.

Hence, the correct option is $B$

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Similar questions

Q. A certain mass of a substance, when dissolved in

100

g C

_{6}

_{6}

, lowers the freezing point by 1.28

^{o}

C. The same mass of solute dissolved in

100

g water lowers the freezing point by

1.40

^{o}

C. If the substance has a normal molecular weight in benzene and is completely ionized in water, thus, how many ions does it dissociate in water?

[

K

_{f}

for H

_{2}

O and C

_{6}

_{6}

are

1.86

and

5.12

K kg mol

^{- 1}

]

Q. A certain mass of a substance, when dissolved in 100 g of

C_{6} H_{6}

, lowers the freezing point by

{1.28}^{o} C

.The same mass of solute dissolved in 100 g of water lowers the freezing point by

{1.40}^{o} C

.If the substance has normal molecular weight in benzene and is completely dissociated in water, into how many ions does it dissociate in water?

K_{f}

for

H_{2} O

and

C_{6} H_{6}

is 1.86 and

5.12 K {m o l}^{- 1} k g

, respectively:

0.440 g

of a substance dissolved in

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of benzene lowered the freezing point of benzene by

{0.567}^{\circ} C

. The molecular mass of the substance (

K_{f} = {5.12}^{\circ} C k g m o l

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Q. When

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dissolved in

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is dissolved in

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K_{f} = 1.86 m o l^{- 1} K k g

. Will either of these dissociate into ions in an aqueous solution?

40

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The correct option is C 3 ionsΔTf=iKfmFor benzene1.28=1×5.12×x100⇒x=25 molFor water 1.40=i×1.86×25100⇒i=3The substance dissociates into three ions in water. Hence, the correct option is B