Van't Hoff Factor

Q.

The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

Q.

A solution containing 30 g of non-volatile solute exactly in 90 g of water has a

vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to

the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate:

1. molar mass of the solute

2. vapour pressure of water at 298 K.

Q.

Vapour pressure of pure water at 298 K is 23.8 mm Hg. 50 g of urea (NH₂CONH₂) is dissolved in 850 g of water. Calculate the vapour pressure of water for this solution and its relative lowering.

Q.

An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?

Q. The $pH$ of the solution containing $50\text{mL}$ each of $0.10$ sodium acetate and $0.01\text{M}$ acetic acid is
[Given $p{K}_a$ of $C{H}_{3}COOH=4.57$]

Q.

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185, 000 in 450 mL of water at 37°C.

Q.

What is the degree of dissociation?

Q.

number of moles of KMnO₄ that is needed to react with one mole of FeC₂O₄ in acidic medium is-

a) 2/5 b)3/5 c)4/5 d)(y-x)

Q.

QUESTION 2.33

19.5 g of $C{H}_{2}FCOOH$ is dissolved in 500g of water. The depression in the freezing point of water observed in 1.0 C. Calculate the van't Hoff factor and dissociation constant of fluoroacetic acid.
$K_f=1.86Kkgmo{l}^{-1}$

Q.

Determine the amount of CaCl2 (i = 2.47) dissolved in 2.5 litre of water such that its osmotic pressure is 0.75 atm at 27°C.

Q.

Define molal elevation constant and molal depression constant?

Q. The mole fraction of glucose in aqueous solution is 0.2 , then molality will be

Q.

The van’ t Hoff factor (i) for a dilute aqueous solution of the strong electrolyte barium hydroxide is

1. 2

2. 3

3. 0

4. 1

Q.

Equal volumes of 0.1M AgNO₃ and 0.2M NaCl are mixed. The concentration of NO^-₃ ions in the mixture will be

Q. When mercuric iodide is added to the aqueous solution of $KI$ then :

1. Freezing point is raised
2. Freezing point does not change
3. Freezing point is lowered
4. Boiling point does not change

Q.

Calculate the concentration of nitric acid in mole per litre in a sample that has a density $1.41g/mL$ and the mass percentage is 69%.

Q. A crystalline salt when heated becomes anhydrous and loses 51.2% of its weight. The anhydrous salt on analysis gave the percentage composition as Mg-20.0% S-26.66% and O-53.33% Calculate the molecular formula of the anhydrous salt and the crystalline salt. Molecular mass of anhydrous salt is 120

Q. The molecular weight of benzoic acid in benzene as determined by depression in the freezing point method corresponds to

1. Ionization of benzoic acid
2. Dimerization of benzoic acid
3. Trimerization of benzoic acid
4. Solvation of benzoic acid

Q.

Which one of the following pairs of solution can we expect to be isotonic at the same temperature

1. 0.1 M urea and 0.1 M NaCl

2. 0.1 M urea and 0.2 M MgCl2

3. 0.1 M NaCl and 0.1M Na2SO4

4. 0.1 M Ca(NO3)2 and 0.1 M Na2SO4

Q. The correct option representing a Freundlich adsorption isotherm is

1. $\frac{x}{m}=k{p}^{0.3}$
2. $\frac{x}{m}=k{p}^{2.5}$
3. $\frac{x}{m}=k{p}^{-0.5}$
4. $\frac{x}{m}=k{p}^{-1}$

Q. A solution containing 10g per dm3 of urea(molecular mass = 60g mol-1) is isotonic with a 5%solution of a nonvolatile solute. The molecular massof this nonvolatile solute is(1) 250g mol-1(3) 350g mol-1(2) 300g mol-1(4) 200g mol-1

Q. How much amount of water can be decomposedthrough electrolysis by passing a current of 4 Ae1.93 x 10^° seconds?2.5 moles of water (2) 3 moles of water(4) 4 moles of water(3) 3.5 moles of water

Q.

Ethylene glycol (molar mass$=62\mathrm{g}{\mathrm{mol}}^{-1}$) is a common automobile antifreeze. calculate the freezing point of a solution containing $12.4\mathrm{g}$ of this substance in $100\mathrm{g}$of water. would it be advisable to keep this substance in the car radiator during summer?

Given: ${\mathrm{k}}_{\mathrm{f}}$ for water $=1.86\mathrm{K}\mathrm{kg}{\mathrm{mol}}^{-1}$, ${\mathrm{k}}_{\mathrm{b}}$ for water $=0.512\mathrm{K}\mathrm{kg}{\mathrm{mol}}^{-1}$

Q. a crystaline solid AB adopts soduim chloride type structure with edge length of unit cell as 745pm and formula mass of 74.5a.m.u the density of crystallie compound is

Q.

An antifreeze solution is prepared from 222.6 g of ethylene glycol (C₂H₆O₂) and 200 g of water. Calculate the molality of the solution. If the density of the solution is 1.072 g mL⁻¹, then what shall be the molarity of the solution?

Q. The degree of dissociation $\left(\alpha \right)$ of a weak electrolyte, $A_x{B}_y$ is related to the van ’t Hoff factor (i) by the expression:

1. $\alpha =\frac{i-1}{(x+y-1)}$
2. $\alpha =\frac{i-1}{(x+y+1)}$
3. $\alpha =\frac{x+y-1}{i-1}$
4. $\alpha =\frac{(x+y+1)}{i-1}$

Q. Van't Hoff factor of centimolal solution of $K_3\left[Fe{\left(CN\right)}_6\right]$ is $\mathrm{3.333.}$ Calculate the percent dissociation of $K_3\left[Fe{\left(CN\right)}_6\right]$(Round off to the nearest integer).

Q.

Question 20
We have three aqueous solutions of NaCl labelled as 'A', 'B' and 'C' with concentrations 0.1 M, 0.01 M and 0.001 M, respectively. The value of van't Hoff factor for these solutions will be in the order ........... .
(a) $i_A<i_B<i_C$ (b) $i_A>i_B>i_C$ (c) $i_A=i_B=i_C$ (d) $i_A<i_B>i_C$

Q. Measuring zeta potential is useful in determining which property of colloidal solution?

1. Viscosity
2. Solubility
3. Stability of the colloidal particles
4. Size of the colloidal particle

Q. The value of van ’t Hoff factor (i) for a solution of ethanoic acid in benzene is:

1. 2
2. 0.5
3. 1
4. 1.5