Which one of the following aqueous solutions will exhibit highest boiling point?
Show Hint
The greater the value of van't Holf factor, the higher will be the elevation in boiling point
0.01 M Na2SO4
0.01 M KNO3
0.015 M urea
0.015 M glucose
The Correct Option is A
Approach Solution - 1
The greater the value of van't Holf factor, the higher will be the elevation in boiling point and therefore higher will be the boiling point of the solution.
| Solution | Van't Hoff Factor |
|---|---|
| 0.01 M Na2SO4 | 3 |
| 0.01 M KNO3 | 2 |
| 0.015 M urea | 2 |
| 0.015 M glucose | 2 |
Hence, 1.0 M Na2SO4 has the highest value of boiling point.
Therefore, of the following aqueous solutions, 1.0 M Na2SO4 will exhibit the highest boiling point
Approach Solution -2
Elevation in boiling point is the colligative property which entirely depends upon the number of solute particles.
In the solution, the greater the number of solute particles, the higher the extent of elevation in the boiling point.
Na2SO4 → 2Na+ + SO42-
Therefore, option A) is the correct answer.
Approach Solution -3
The Correct option is (A)
The elevation in boiling point is a colligative property of the solution.
Hence the elevation in boiling point ∝ concentration of solute particles
In, the dissociation of Sodium sulfate:
Na2SO4 → 2Na+ + SO42-
Concentration of ions in 0.01M Na2SO4 solution = 3 x 0.01 = 0.03M
- Options C and D are incorrect as Urea and Glucose are covalent molecules that do not undergo dissociation.
- Thus, the concentration of solute particles in these solutions is 0.015 M.
In the dissociation of KNO3:
KNO3 → K+ + NO3-
Concentration of ions in 0.1 M KNO3 solution = 2 x 0.01 = 0.02 M
Therefore, the highest number of solute particles is in 0.01M Na2SO4 solution.
Thus, 0.01M Na2SO4 will show the highest boiling point.
Top Questions on Colligative Properties
- Mass of glucose (\(C_6H_{12}O_6\)) required to be dissolved to prepare one litre of its solution which is isotonic with \(15 \, \text{g L}^{-1}\) solution of urea (\(NH_2CONH_2\)) is:
{Given:} Molar mass in \(\text{g mol}^{-1}\): \[ C : 12, \, H : 1, \, O : 16, \, N : 14 \]- NEET (UG) - 2024
- Chemistry
- Colligative Properties
- An artificial cell is made by encapsulating \(0.2 \, \text{M}\) glucose solution within a semipermeable membrane. The osmotic pressure developed when the artificial cell is placed within a \(0.05 \, \text{M}\) solution of NaCl at 300 K is ______ \( \times 10^{-1} \, \text{bar} \). (Nearest Integer)
Given: \(R = 0.083 \, \text{L bar mol}^{-1} \text{K}^{-1}\)
Assume complete dissociation of NaCl.- JEE Main - 2024
- Chemistry
- Colligative Properties
- Consider the dissociation of the weak acid HX as given below:
\[\text{HX(aq)} \rightleftharpoons \text{H}^+(\text{aq}) + \text{X}^-(\text{aq}), \, K_a = 1.2 \times 10^{-5}\]
\([K_a: \text{dissociation constant}]\)
The osmotic pressure of \(0.03 \, \text{M}\) aqueous solution of HX at 300 K is ______ \( \times 10^{-2} \, \text{bar} \) (nearest integer).
Given: \(R = 0.083 \, \text{L bar mol}^{-1} \text{K}^{-1}\)- JEE Main - 2024
- Chemistry
- Colligative Properties
- Considering acetic acid dissociates in water, its dissociation constant is $6.25 \times 10^{-5}$. If 5 mL of acetic acid is dissolved in 1 litre water, the solution will freeze at $-x \times 10^{-1}$ °C, provided pure water freezes at 0 °C. $x = $ _____ (Nearest integer)
Given: $(K_f)_{water} = 1.86$ K kg mol$^{-1}$
density of acetic acid is 1.2 g mol$^{-1}$
molar mass of water = 18 g mol$^{-1}$
molar mass of acetic acid = 60 g mol$^{-1}$
density of water = 1 g cm$^{-3}$
Acetic acid dissociates as CH$_3$COOH $\rightleftharpoons$ CH$_3$COO$^-$ + H$^+$- JEE Main - 2024
- Chemistry
- Colligative Properties
- A solution containing \(10 \, \text{g}\) of an electrolyte \(AB_2\) in \(100 \, \text{g}\) of water boils at \(100.52^\circ \text{C}\). The degree of ionization of the electrolyte (\(\alpha\)) is _____ \(\times 10^{-1}\). (nearest integer)
\([ \text{Given: Molar mass of } AB_2 = 200 \, \text{g mol}^{-1}, \, K_b \, (\text{molal boiling point elevation const. of water}) = 0.52 \, \text{K kg mol}^{-1}, \text{ boiling point of water} = 100^\circ \text{C}; \, AB_2 \text{ ionises as } AB_2 \rightarrow A^{2+} + 2B^- ]\)- JEE Main - 2024
- Chemistry
- Colligative Properties
Questions Asked in JCECE exam
- In the figure, the ball P is released from rest, when the spring is at its natural length. For the block Q of mass $ 2{{m}_{0}} $ to leave contact with ground at some stage, the minimum mass of P must be
- JCECE - 2015
- Conservation of energy
- The effective resistance across the points P and Q is
- JCECE - 2015
- Current electricity
- A $ 50\,\Omega $ galvanometer is shunted by a resistance of $ 5\,\Omega . $ The percentage of the total current, which passes through the galvanometer is
- JCECE - 2015
- Current electricity
- A disc of radius a and mass m is pivoted at the rim and is set in small oscillation. If a simple pendulum have the same period as that of the disc, then the length of the simple pendulum should be
- JCECE - 2015
- Oscillations
- An elliptically shaped ring of dimensions shown in figure just touches, the horizontal surface of a liquid of surface tension S. The force required to pull the ring away from the liquid surface is
- JCECE - 2015
- Surface tension
Concepts Used:
Colligative Properties
Colligative Property of any substance is entirely dependent on the ratio of the number of solute particles to the total number of solvent particles but does not depend on the nature of particles. There are four colligative properties: vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.
Examples of Colligative Properties
We can notice the colligative properties of arrangements by going through the accompanying examples:
- On the off chance that we add a spot of salt to a glass full of water, its freezing temperature is brought down impressively than its normal temperature. On the other hand, the boiling temperature is likewise increased and the arrangement will have a lower vapor pressure. There are also changes observed in its osmotic pressure.
- In the same way, if we add alcohol to water, the solution’s freezing point goes down below the normal temperature that is usually observed for either pure alcohol or water.
Types of Colligative Properties
- Freezing point depression: ΔTf =1000 x kf x m2 /(M2 x m1)
- Boiling point elevation: ΔTb = kb m
- Osmotic pressure: π = (n2/V) RT
- Relative lowering of vapor pressure: (Po - Ps)/Po