Elevation in Boiling Point

Q.

The boiling point of benzene is 353.23 K. When 1.80 g of a non-volatile solute was dissolved in 90 g benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of the solute. $\left(K_{b}forbenzeneis2.53Kkgmo{l}^{-1}\right)$

1. $58.0gmo{l}^{-1}$

2. $68.0gmo{l}^{-1}$

3. $78.0gmo{l}^{-1}$

4. $48.0gmo{l}^{-1}$

Q. All the process of calculation of volume - strength of H2O2

Q.

Molarity of the concentrated HCl if the density is 1.17g/ml

Q. 1 g of non-electrolyte solute dissolved in 50g of benzene lowered the freezing point of benzene by 0.40K. The freezing point depression constant of benzene is 5.12 K kg/mol. Find the molar mass of the solute.

Q.

18g of glucose $\left(C_6{H}_{12}{O}_6\right)$ is dissolved in 1 kg of water in a saucepan. At what temperature will the water boil (at 1 atm)? $K_b$ for water is $0.52Kkgmo{l}^{-1}$.

1. 373.202K

2. 365.202K

3. 370.202K

4. 473.202K

Q.

What is the concentration of NO3- ions when equal volume of 0.1M AgNO3 and 0.1M NaCl are mixed together?

Q. molality of aqueous solution is 11.11.what is the mole fraction of solute in the solution

Q.

A $1$ molal $K_{4}Fe{\left(CN\right)}_6$ solution has a degree of dissociation of $0.4$. Its boiling point is equal to that of another solution which contains $18.1$ weight per cent of a nonelectrolyte solute $A$. The molar mass of $A$ is ________ $\mathrm{g}/\mathrm{mol}$. (Round off to the Nearest Integer).

Q.

Which of the following solutions will have the highest boiling point?

1. 1% sucrose

2. 1% glucose

3. 1% NaCl

4. 1% CaCl₂

Q.

The boiling point of water (100°C) becomes 100.52°C, if 3 grams of a non-volatile solute is dissolved in 200ml of water. The molecular weight of

solute is

1. 15.4 g mol

2. 
   

3. 17.3 g mol^-1

4. 20.4 g mol

Q. Calculatethe mole fraction of toluene in the vapour phase which is in equilibrium with a solution of benzene and toluene having a mole fraction of toluene 0.5. (The vapour pressure of pure benzene is 119 torr and that of toluene is 37 torr at the same temperature)

Q.

If 0.15g of a solute dissolved in 15g of solvent is boiled at a temperature higher by 0.216⁰C than that of the pure solvent, then the molecular weight of the

substance is (molal elevation constant for the solvent is 2.16):

1. 1.01

2. 10

3. 10.1

4. 100

Q. $200\text{mL}$ of an aqueous solution of a protein contains its $1.26\text{g}$. The osmotic pressure of this solution at $300\text{K}$ is found to be $2.52\times {10}^{-3}$ bar. The molar mass of protein will be
$(R=0.08{\text{L bar mol}}^{-1}{\text{K}}^{-1})$

1. $51022{\text{g mol}}^{-1}$
2. $122044{\text{g mol}}^{-1}$
3. $31011{\text{g mol}}^{-1}$
4. $60000{\text{g mol}}^{-1}$

Q. Which colligative property is preferred for the molar mass determination of macromolecules?

Q.

For a dilute solution containing 2.5 g of a non-volatile non-electrolyte solute in 100 g of water, the elevation in boiling point at 1 atm pressure is $2^{\circ }C$. Assuming concentration of solute is much lower than the concentration of solvent, the vapour pressure (mm of Hg) of the solution is (take $K_b$=0.76K kg $mo{l}^{-1}$).

1. 740

2. 724

3. 718

4. 736

Q. What would be the freezing point of aqueous solution containing 17 g of $C_2{H}_{5}OH$ in 1000 g of water. $K_{fwater}=1.86K{m}^{-1}$.

1. $-{0.69}^{\circ }C$
2. $-{0.34}^{\circ }C$
3. ${0.0}^{\circ }C$
4. ${0.34}^{\circ }C$

Q.

A 0.2 molal aqueous solution of a weak acid (HX) is 20% ionised. The freezing point of this solution is (Given for water)

1. - 0.31° C

2. - 0.53°C

3. - 0.90°C

4. - 0.45°C

Q.

Mole fraction of methanol in its aqueous solution is 0.5. the concentration of solution in terms of percent by mass of methanol is :

A 36

B 50

C 64

D 72

Q.

Pressure cooker reduces cooking time for food because:

1. Cooking involves chemical changes helped by a rise in temperature
2. Heat is more evenly distributed in the cooking space
3. Boiling point of water involved in cooking is increased
4. The higher pressure inside the cooker crushes the food material

Q.

Density of water is 1g/mL. The concentration of water in mol/litre is:

1. 1000

2. 0.018

3. 55.5

4. 18

Q. A solution containing $2.5\times {10}^{-3}kg$ of a solute dissolved in $75\times {10}^{-3}kg$ of water boils at $373.535K.$ The molar mass of the solute is _____ $gmo{l}^{-1}$. [nearest integer] (Given : $K_b\left(H_{2}O\right)=0.52Kkgmo{l}^{–1}$ and boiling point of water $=373.15K)$

Q.

The boiling point of a solution of 0.105 gm of a substance in 15.84 gram of ether was found to be 100°C higher than that of pure ether. What is the molecular weight of the substance [Molecular elevation constant of ether per 100 g = 21.6]

1. 144.50

2. 146.66

3. 143.18

4. 140.28

Q.

Normal boiling point of water is 373 K (at 760mm). Vapour pressure of water at 298 K is 23 mm. If the enthalpy of evaporation is 40.656 kJ/mole, the boiling point of water at 23 mm pressure will be

1. 250 K

2. 12.5 K

3. 294 K

4. 51.6 K

Q.

Which of the following will have the highest boiling point at 1 atm pressure:

1. 0.1 M sucrose

2. 0.1 M NaCl

3. 0.1 M BaCl₂

4. 0.1 M glucose

Q.

Lowering of vapour pressure is highest for

1. 0.1M BaCl₂

2. 0.1M Urea

3. 0.1M MgSO₄

4. 0.1M Ethanol

Q. The boiling point of a solution made by dissolving 12.0 g of glucose in 100 g of water is ${100.34}^{\circ }C$. Calculate the molecular weight of glucose; $K_b$ for water $={0.52}^{\circ }C/m$.

1. $183.5gmo{l}^{-}1$
2. $283.5gmo{l}^{-}1$
3. $383.5gmo{l}^{-}1$
4. $73.5gmo{l}^{-}1$

Q. The elevation in boiling point for 1 molal solution of non-volatile solute $A$ is $3K$. The depression in freezing point for 2 molal solution of A in the same solvent is $6K$. The ratio of $K_b$ and $K_f$ i.e., $\frac{K_b}{K_f}$ is $1:X$. The value of $X$ is [nearest integer]

Q. Explain mixed melting point

Q. Calculate the boiling point of a $1M$ aqueous solution (Density - $1.04g$ $m{L}^{-1}$) of potassium chloride.
$K_b$ for water = $0.52Kkgmo{l}^{-1}$.
Atomic mass of $K=39g/mol$
Atomic mass of $Cl=35.5g/mol$

1. a. $374.07K$
2. b. $274.11K$
3. c. $378.11K$
4. d. $473.11K$

Q. In a 0.2 molal aqueous solution of a weak acid HX, the degree of ionization is 0.3 at room temperature. Taking $K_f$ for water as $1.85{}^{o}C{m}^{-1}$, the freezing point of the solution will be nearest to

1. $-0.481{}^{\circ }C$
2. $-0.360{}^{\circ }C$
3. $-0.260{}^{\circ }C$
4. $-0.150{}^{\circ }C$