The addition of 3 g of a substance to 100 g CCl 4 M = 154 g mol - 1 raises the boiling point of CCl 4 by 0 . 60 ° C . If K b CCl 4 is 5 K mol - 1 kg , calculate the freezing point depression. Given : K f CCl 4 = 32 . 0 K kg mol - 1 .

Given: weight of solute = 3 g , ∆ T b = 5 . 03 K Kg mole - 1 , K f = 32 . 0 K Kg mole - 1 The depression in freezing point ∆ T f = K f × m The elevation in boiling point ∆ T b = K b × m where K f = molal depression constant K b = molal elevation constant m = molality thus, ΔT f ΔT b = K f K b ⇒ ΔT f = 32 5 . 03 × 0 . 6 ⇒ ∆ T f = 3 . 793 ˚ C Hence, the freezing point depression is 3 . 793 ˚ C

A solution containing 0 . 011 kg of barium nitrate Ba NO 3 2 in 0 . 1 kg of water boils at 100 . 46 ° C . Calculate the degree of ionization of the salt. K b (water) = 0 . 52 K kg mol - 1 . Ba = 137

Given: Weight of barium nitrate = 0 . 011 kg , the boiling point of water = 100 . 46 ° C , K b = = 0 . 52 K kg mol - 1 Elevation in boiling point = 100 . 46 ° C - 100 ° C = 0 . 46 ° C But ∆ T b = iK b m Where m = molality m = moles of solute wt . of solvent Kg m = 0 . 011 × 10 3 261 0 . 1 ⇒ 0 . 46 = i × 0 . 52 × 0 . 011 × 10 3 0 . 1 × 261 ⇒ i = 2 . 098 Degree of ionization α = i - 1 n - 1 n = 3 for Ba NO 3 2 ⇒ α = 2 . 098 - 1 3 - 1 ⇒ α = 0 . 55 Hence, the degree of ionization of the salt is 0 . 55

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Acetone and carbon disulphide form binary liquid solution showing positive deviation from Raoult law. The normal boiling point $(T_{b})$ of pure acetone is less than that of pure ${CS}_{2}$ . Pick out the incorrect statements among the following.

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 16

The freezing point of ether was lowered by

0.60 ° C

on dissolving

2.0 g

of phenol in

100 g

of ether. Calculate the molar mass of phenol and comment on the result. Given :

K_{f}

(ether)

= 5.12 K kg {mol}^{- 1}

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 17

The addition of

3 g

of a substance to

100 g {CCl}_{4} (M = 154 g {mol}^{- 1})

raises the boiling point of

{CCl}_{4}

0.60 ° C

. If

K_{b} ({CCl}_{4})

5 K {mol}^{- 1} kg

, calculate the freezing point depression.
Given :

K_{f} ({CCl}_{4}) = 32.0 K kg {mol}^{- 1}

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 18

500 gm

of water

3.0 \times 10^{- 3} kg

of acetic acid is added. If

23 %

of acetic acid is dissociated, what will be the depression of freezing point?

K_{f} = 1.86 K kg {mol}^{- 1}

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 19

0.01 m

aqueous solution of

K_{3} [Fe {(CN)}_{6}]

freezes at

- 0.062 ° C .

What is the apparent percentage of dissociation ? (

K_{f}

for water

= 1.86 K kg {mol}^{- 1}

)

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 20

A solution containing

0.011 kg

of barium nitrate

[Ba {({NO}_{3})}_{2}]

0.1 kg

of water boils at

100.46 ° C

. Calculate the degree of ionization of the salt.

K_{b}

(water)

= 0.52 K kg {mol}^{- 1}

[Ba = 137]

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 24

A certain mass of a substance, when dissolved in

100 g C_{6} H_{6}

, 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?

K_{f}

for

H_{2} O

and

C_{6} H_{6}

are

1.86

and

5.12 K kg {mol}^{- 1}

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 25

300 K

, two solutions of glucose in water of concentration

0.01 M

and

0.001 M

are separated by semipermeable membrane. Pressure needs to be applied on a solution, to prevent osmosis? Calculate the magnitude of this applied pressure in atm?

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Beta Question Bank for Engineering: Chemistry>Chapter 8 - Solutions>EXERCISE-3>Q 26

The vapour pressure of ethanol and methanol are

44.0 mm

and

88.0 mm Hg

respectively. An ideal solution is prepared at the same temperature by mixing

69 g

of ethanol with

40 g

of methanol. Calculate total vapour pressure of the solution.

Acetone and carbon disulphide form binary liquid solution showing positive deviation from Raoult law. The normal boiling point Tb of pure acetone is less than that of pure CS2. Pick out the incorrect statements among the following.

Important Questions on Solutions

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Acetone and carbon disulphide form binary liquid solution showing positive deviation from Raoult law. The normal boiling point $(T_{b})$ of pure acetone is less than that of pure ${CS}_{2}$ . Pick out the incorrect statements among the following.