Question

50 ⓟⓞⓘⓝⓣⓢ

ⓟⓛⓩ ⓓⓞⓝⓣ ⓢⓟⓐⓜ ❤

class-12____sub-chemistry
_______chapter-Solutions​

Answer 1

$\textsf{\underline {\Large{SOLUTIONS}}}$ :

$\textsf{\underline {\large{Deviation of real solutions from Raoult's law}}}$ :

Real solutions can show either positive or negative deviation from Raoult's law.

$\textsf{\underline {\large{Positive Deviation}}}$ :

1 ). Deviation will be called positive when partial pressure of each component and resultant total pressure is greater than the pressure expected on the basis of Raoult's law.

$\mathsf{P_T\:>\:P_A\:+\:P_B}$

$\mathsf{P_A\:>\:{P_A} ^{\circ} {\chi{_A}}}$ and $\mathsf{P_B\:>\:{P_B} ^{\circ} {\chi{_B}}}$

2. In such cases, intermolecular forces between solvent - solute molecules ($\mathsf{F_{A-B}}$) are weaker than those between solvent - solvent and solute - solute molecules.

$\mathsf{F_{A-B}}$ < $\mathsf{F_{A-A}}$ / $\mathsf{F_{B-B}}$

3. This shows that molecules of A or B will escape more easily from surface of the solution.

$\textsf{\underline {\large{Characteristics of +ve deviation}}}$

1. $\mathsf{P_A\:>\:{P_A} ^{\circ} {\chi{_A}}}$ or $\mathsf{P_B\:>\:{P_B} ^{\circ} {\chi{_B}}}$

2. $\mathsf{\Delta{_{mix}} H\:>\:0}$ i. e. Positive.

3. $\mathsf{\Delta{_{mix}} V\:>\:0}$ i. e. Positive.

Example :

↪️Ethyl Alcohol in water.

↪️Acetone in ($\mathsf{CS_2}$).

↪️$\mathsf{CCl_4}$ in Benzene.


$\textsf{\underline {\large{Negative Deviation}}}$ :

1. If partial pressure of each component of A and B and resultant total vapour pressure are less than pressure expected on the basis of Raoult's law.

$\mathsf{P_T\:<\:P_A\:+\:P_B}$

$\mathsf{P_A\:<\:{P_A} ^{\circ} {\chi{_A}}}$

$\mathsf{P_B\:<\:{P_B} ^{\circ} {\chi{_B}}}$

2. In such cases, intermolecular forces between solvent - solute molecules ($\mathsf{F_{A-B}}$) is greater than those between solvent - solvent and solute - solute molecules.

$\mathsf{F_{A-B}}$ > $\mathsf{F_{A-A}}$ / $\mathsf{F_{B-B}}$

3. This shows that molecules of A or B will escape less easily from surface of the solution.

$\textsf{\underline {\large{Characteristics of -ve deviation}}}$

1. $\mathsf{P_A\:<\:{P_A} ^{\circ} {\chi{_A}}}$ or $\mathsf{P_B\:<\:{P_B} ^{\circ} {\chi{_B}}}$

2. $\mathsf{\Delta{_{mix}} H\:<\:0}$ i. e. Negative.

3. $\mathsf{\Delta{_{mix}} V\:<\:0}$ i. e. Negative.

Example :

↪️ $\mathsf{HNO_3}$ in $\mathsf{H_{2}O}$

↪️ Chloroform in acetone.

↪️ Acetic acid in Pyridine.

↪️HCl in $\mathsf{H_{2}O}$.

Answer 2

$\Large\frak{\underline{\underline{Question:}}}$

Explain deviations of real solutions from Rault's law..

$\rule{200}3$

$\Large\frak{\underline{\underline{Answer:}}}$

$\textsf{\underline {\large{Deviation of real solutions from Raoult's law}}}$

Real solutions can show either positive or negative deviation from Raoult's law.

$\textsf{\underline {\large{Positive Deviation}}}$

1 ). Deviation will be called positive when partial pressure of each component and resultant total pressure is greater than the pressure expected on the basis of Raoult's law.

$\mathsf{P_T\:>\:P_A\:+\:P_B}$

$\mathsf{P_A\:>\:{P_A} ^{\circ} {\chi{_A}}}$

$\rule{200}3$

#own composition ✔