Abnormal Colligative Properties

Q.

Calcium carbonate reacts with aqueous $\mathrm{HCl}$to give ${\mathrm{CaCl}}_2$ and ${\mathrm{CO}}_2$according to the reaction given below

$\underset{\mathrm{Calcium}\mathrm{Carbonate}}{{\mathrm{CaCO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}⟶\underset{\mathrm{Calcium}\mathrm{Chloride}}{{\mathrm{CaCl}}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

What mass of ${\mathrm{CaCO}}_3$ is required to react completely with 25 mL of 0.75 M HCl?

1) 0.6844

2) 0.9375

3) 0.4265

4) 0.2785

Q. 224 mL of $S{O}_{2\left(g\right)}$ at 298 K and 1 atm is passed through 100 mL of 0.1 M NaOH solution . The non - volatile solute produced is dissolved in 36 g of water . The lowering of vapour pressure of solution ( assuming the solution is dilute ) ($P_{\left(H_{2}O\right)}=24mmofHg$) is $x\times {10}^{-2}$ mm of Hg , the value of x is (Integer answer )

Q.

Which Of the following 0.2m aqueous solutions will exhibit the largest freezing point depression. 1) glucose 2) sucrose 3)urea 4)nacl

Q. Give reasons for the following :

(a) Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.

(b) Aquatic animals are more comfortable in cold water than in warm water.

(c) Elevation of boiling point of 1 M KCI solution is nearly double than that of 1 M sugar solution.

Q.

Calculate the mass of ascorbic acid (Vitamin C, C₆H₈O₆) to be dissolved in
75 g of acetic acid to lower its melting point by 1.5°C. K_f = 3.9 K kg mol⁻¹.

Q.

In the aquous solution of Sulphuric acid the Mole fraction of water is 0.85 the molality of solution is?

Q. Which one of the following 0.06 M aqueous solution has lowest freezing point?

1. $C_6{H}_{12}{O}_6$
2. $K_{2}S{O}_4$
3. $A{l}_2(S{O}_4{)}_3$
4. $KI$

Q.

Mole fraction in benzene of iodine is 0.2 than what is the molality of benzene ?

A)2.35 B)3.20 C)2.75 D)3.6

Q.

The freezing point of equimolal aqueous solution will be highest for

1. C₆H₅NH₃Cl (aniline hydrochloride)
2. Ca(NO₃)₂
3. La(NO₃)₂
4. C₆H₁₂O₆ (glucose)

Q. The vapour pressure of a solution having 2.0 g of solute X (gram atomic mass=32 g/mol) in 100 g of CS2 (vapour pressure =854torr) is 848.9 torr.The molecular formula of solute 1) X 2)X2 3)X4 4)X8

Q. The freezing point of benzene decreases by ${0.45}^{\circ }C$ when 0.2g of acetic acid is added to 20g 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 = 5.12K kg $mo{l}^{-1}$)

1. 64.6%
2. 94.6%
3. 80.4%
4. 74.6%

Q.

The osmotic pressure of equimolar solutions of ${\mathrm{BaCl}}_2$, $\mathrm{NaCl}$ and glucose will be in the order:

1. ${\text{Glucose > NaCl > BaCl}}_{\text{2}}$

2. ${\text{BaCl}}_2>\text{NaCl > Glucose}$

3. $\mathrm{NaCl}>{\mathrm{BaCl}}_2>\mathrm{Glucose}$

4. $\mathrm{NaCl}>\mathrm{Glucose}>\mathrm{Ba}$

Q. The van ’t Hoff factor of $H{g}_{2}C{l}_2$ in its aqueous solution will be $(H{g}_{2}C{l}_2$ is 80% ionized in the solution):

1. 1.6
2. 2.6
3. 3.6
4. 4.6

Q. What will be the elevation in boiling point for $13.44g$ of $CuC{l}_2$ dissolved in $1kg$ of water as solvent if $CuC{l}_2$ is fully ionised?
($K_b=0.52Kkgmo{l}^{-1}$
Molar mass of $CuC{l}_2=134.4g/mol$)

1. 0.05
2. 0.10
3. 0.16
4. 0.20

Q.

The density of 3M aqueous solution of sodium thiosulphate is 1.25g/ml. Calculate (1) mole fraction of sodium thiosulphte (2) molalities of Na^+ and S2O3^-2 ions.

Q. $5\%\left(w/v\right)$ solution of glucose is isotonic with $2\%\left(w/v\right)$ solution of a non-volatile non electrolyte substance at same ‘T’. The molecular mass of the substance will be:
[0.77 Mark]

1. $36\text{g}$
2. $72\text{g}$
3. $78\text{g}$
4. $90\text{g}$

Q. A compound X undergoes tetramerisation in a given organic solvent. The van ’t Hoff factor ‘i’ is calculated as 0.05y. Find y. (Assuming 100% association)

Q.

Pure water freezes at 273 K and 1 bar. The addition of 34.5g of ethanol to 500g of water changes the freezing point of the solution. Use the freezing point depression constant of water as 2K kg $mo{l}^{-1}$. The figures shown below represent plots of vapour pressure (V.P.) versus temperature (T). [Molecular weight of ethanol is 46g $mo{l}^{-1}$]

Among the following, the option representing change in the freezing point is

1. 
2. 
3. 
4. 

Q. why benzoic acid is more acidic than acetic aci

Q.

The molarity of Cl^- in an aqueous solution which has w/v 2% NaCl, 4% CaCl₂ and 6% NH₄Cl will be

a) 0.342

b) 0.721

c) 1.12

d) 2.18

Q. A certain substance 'A' tetramerises in water to the extent of 80%. A solution of $2.5g$ of A in $100g$ of water lowers the freezing point by ${0.3}^{\circ }C.$ The molar mass of A in (g/mol) is:
(Molal depression constant of A is $1.86Kkgmo{l}^{-1}$)

1. 122
2. 31
3. 244
4. 62

Q. $40g$ of glucose (Molar mass $=180)$ is mixed with $200mL$ of water. The freezing point of solution is ________$K$. (Nearest integer)
$\text{[Given}:K_f=1.86Kmo{l}^{-1}\text{Density of water}=1.00gc{m}^{-3};\text{Freezing point water}=273.15K]$

Q.

A welding fuel gas combines carbon and Hydrogen only. On burning it gives 3.38g of CO2 and 0.690g of water and no other products. A volume of 10L (STP) of this gas found to weigh 11.6g. Calculate empirical formula.

Q. In a solvent 50% benzoic acid dimerises while rest ionises, determine molar mass of acid is observed and also its vant Hoff factor

Q.

The degree of dissociation of $Ca(N{O}_3{)}_2$ in a dilute aqueous solution containing 7 g of salt in 100 g of water at ${100}^{\circ }C$ is $70\%$. The vapour pressure of solution is:

1. 746.27 mm of Hg
2. 745.27 mm of Hg
3. 744.27 mm of Hg
4. 743.27 mm of Hg

Q. The boiling point of a solution containing 0.61 g of benzoic acid in 50 g of carbon disulphide assuming $84\%$ dimerization of the acid, where boiling point and Kb of $C{S}_2$ being ${46.2}^{\circ }C$ and $2.3Kkgmo{l}^{-1}$ is :

1. ${46.3444}^{\circ }C$
2. ${46.3434}^{\circ }C$
3. ${46.3344}^{\circ }C$
4. ${46.3334}^{\circ }C$

Q. If $5g$ of $N{a}_{2}S{O}_4$ is dissolved in $45g$ of $H_{2}O$, the freezing point is changed by ${3.72}^{\circ }C$. Calculate the van't Hoff factor for $N{a}_{2}S{O}_4$.
Given: Freezing point depression constant for water is ${1.86}^{\circ }Ckgmo{l}^{-1}$

1. 1.85
2. 2.56
3. 3.11
4. 3.8

Q.

An aqueous solution of a weak monobasic acid containing 0.1 g in 21.7g of water freezes at 272.813 K. If the value of K_f for water is 1.86 K/m, what is the molecular mass of the monobasic acid?

1. 50 g/mole

2. 46 g/mole

3. 55 g/mole]y60 g/mole

Q.

10ml of concentrated H₂SO₄ (18M) is diluted to one litre. The approximate strength of the dilute acid is

(1)18 M (2)180 M (3)0.18 M (4)1.8M

Q.

Calculate the mole fraction of ethylene glycol. In the solution containing 20% by mass.