Question:
Pure benzene freezes at $5.3^{\circ} C$. A solution of $0.223 \,g$ of phenylacetic acid $(C_6H_5CH_2COOH)$ in $4.4\, g$ of benzene $(h_f = 5.12\,kg\,mol^{-1})$ freezes at $4.47^{\circ} C$. From this observation, one can conclude that
Pure benzene freezes at $5.3^{\circ} C$. A solution of $0.223 \,g$ of phenylacetic acid $(C_6H_5CH_2COOH)$ in $4.4\, g$ of benzene $(h_f = 5.12\,kg\,mol^{-1})$ freezes at $4.47^{\circ} C$. From this observation, one can conclude that
Updated On: Jul 28, 2022
- phenylacetic acid exists as such in benzene
- phenylacetic acid undergoes partial ionisation in benzene
- phenylacetic acid undergoes complete ionisation in benzene
- phenylacetic acid dimerises in benzene
Hide Solution
Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Depression in freezing point, $\Delta T_{f}=k_{f} m$
(where $m=$ molality)
$=5.12 \times \frac{0.223 \times 1000}{4.4 \times 136}$
$=5.12 \times 0.372$
$=1.91^{\circ} C$
$\therefore$ Theoretical $\Delta T_{f}=1.91$
Actual $\Delta T_{f}=5.3^{\circ} C -4.47^{\circ} C$
$=0.83^{\circ} C$
$\therefore i=\frac{0.83}{1.91}=0.43$
$\because i < 1 $
$ \therefore $ Association will take place.
Thus, it can be said that phenylacetic acid dimerises in benzene.
Was this answer helpful?
0
0
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
View More Questions
Questions Asked in AFMC exam
- 1200 ml of air remaining in lungs even after forceful expiration is
- AFMC - 2012
- Exchange Of Gases
- A dicot plant in which scattered vascular bundles are present in stem is
- AFMC - 2012
- Anatomy of Flowering Plants
- Which plays an important role in the dispersal of spores in Funaria?
- AFMC - 2012
- Kingdom Plant
- Sexual reproduction in eubacteria takes place by
- AFMC - 2012
- Kingdom Monera
- Which of the following acid is also a vitamin?
- AFMC - 2012
- Digestion and absorption
View More Questions
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