Molality is defined as the number of moles of the solute particles which dissolved in unit weight of the solvent. It can be represented by the symbol m . m = Number of moles of solute Mass of the solvent ( in kg ) m = n B W A ( kg ) ∵ n B = W B M B m = W B M B × 1000 W A Where W B and W A are the mass of solute and solvent, respectively.

What is freezing point of a liquid? The freezing point of pure benzene is 278.4 K. Calculate the freezing point of the solution when 2.0 g of a solute having molecular weight 100 g mol - 1 is added to 100 g of benzene. (Kf of benzene = 5 . 12 K kg mol - 1 .)

The Freezing point is the temperature of a liquid at which it changes its state from liquid to solid at atmospheric pressure. We know, ∆ T f = 1000 K f W 2 M 2 W 1 ∆ T f = 1000 × 5 . 12 × 4 100 × 200 = 1 . 024 K T f = T f ∘ - ∆ T f = 278 . 4 - 1 . 024 = 277 . 376 K

Derive van’t Hoff general solution equation for ‘n’ moles of solute.

Consider a dilute solution of a volume V (in dm3) containing W grams of a substance having molecular weight M at an absolute temperature T. Then, concentration of the solution, C=n/V and No. of moles of the substance, n=W/M. By Boyle's law, at a constant temperature, the osmotic pressure of a solution is directly proportional to its molar concentration or inversely proportional to the volume of the solution. Thus, π α C (when temperature is constant) Charle's law at the constant concentration the osmotic pressure of a dilute solution is directly proportional to the absolute temperature(T) i.e. π α C π α CT v = CRT . The equation is called Van't Hoff general solution equation. R is constant of proportionality, also called general solution constant or gas constant.

Molality is defined as the number of moles of the solute particles which dissolved in unit weight of the solvent. It can be represented by the symbol m . m = Number of moles of solute Mass of the solvent ( in kg ) m = n B W A ( kg ) ∵ n B = W B M B m = W B M B × 1000 W A Where W B and W A are the mass of solute and solvent, respectively.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2019>Q 5

HARD

12th Maharashtra Board

IMPORTANT

Earn 100

Derive van’t Hoff general solution equation.

Important Questions on Solutions and Colligative Properties

EASY

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2019>Q 6

Define the following term:

Isotonic solution

EASY

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2019>Q 7

Define the following term:

Hypertonic solution

EASY

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2019>Q 8

Define the following term:

Hypotonic solution

EASY

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2020>Q 9

What is the concentration of dissolved oxygen at

50 ° C

under pressure of one atmosphere if partial pressure of oxygen at

50 ° C

is

0.14 atm

.

(

Henry’s law constant for oxygen

= 1.3 \times 10^{- 3} mol {dm}^{- 3} {atm}^{- 1}

)

EASY

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2020>Q 10

Define: Molality

EASY

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2020>Q 11

Define: Osmotic pressure

HARD

12th Maharashtra Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter 2 - Solutions and Colligative Properties>Maharashtra Board-2020>Q 12

Derive the mathematical expression between molar mass of a non-volatile solute and elevation of boiling point.
State and explain van’t Hoff-Avogardo’s law.

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