Write Raoult's Law for Non-Volatile solute and volatile solvent a… - Vidyadip

Question

Write Raoult's Law for Non-Volatile solute and volatile solvent and derive it's formula.

✓

Answer

→ The vapour pressure of a solvent in solution is less than that of the pure solvent.
→ Raoult established that the lowering of vapour pressure depends only on the concentration of the solute particles and it is independent of their identity.
→ A relation between vapour pressure of the solution, mole fraction and vapour pressure of the solvent,
$p_1=p_1^0 \cdot x_1$
→ The reduction in the vapour pressure of solvent $\left(\Delta p_1\right)$ is given as :
$
\begin{aligned}
\Delta p_1 & =p_1^0-p_1 \\
\therefore \Delta p_1 & =p_1^0-p_1^0 \cdot x_1 \\
\therefore \Delta p_1 & =p_1^0\left(1-x_1\right) \\
\therefore \Delta p_1 & =p_1^0 x_2
\end{aligned}
$
→ The lowering of the vapour pressure is directly proportional to mole-Fraction of solute.
$\begin{aligned} \therefore \frac{\Delta p_1}{p_1^0} & =x_2 \\ \therefore \frac{p_1^0-p_1}{p_1^0} & =x_2 \\ \therefore \frac{p_1^0-p_1}{p_1^0} & =\frac{n_2}{n_1+n_2} \quad\left(\because x_2=\frac{n_2}{n_1+n_2}\right)\end{aligned}$
Where, $n_1=$ Moles of solvent
$n_2=$ Moles of solute
→ For dilute solutions $n _2 \ll n _1$
$\begin{aligned} \frac{p_1^0-p_1}{p_1^0} & =\frac{n_2}{n_1} \\ \therefore \frac{p_1^0-p_1}{p_1^0} & =\frac{ W _2 \times M _1}{ M _2 \times W _1}\end{aligned}$
Where, $\begin{aligned} W _1 & =\text { Weight of solvent } \\ W _2 & =\text { Weight of solute } \\ M _1 & =\text { Molar mass of solvent } \\ M _2 & =\text { Molar mass of solute } \\ p_1^0 & =\text { Vapour pressure of pure solvent } \\ p_1 & =\text { Vapour pressure of solution }\end{aligned}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "4 Marks Questions" from Solutions→Solutions — all question types→Chemistry STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

Explain Raoult's Law for volatile solute and Volatile solvent and derive formula for total vapour pressure with graph.

The product formed by the reaction of ethyl alcohol with conc. $H _2 SO _4$ depends on the reaction conditions. Explain this fact using different equations.

What are enzymes?

Write one chemical equation to illustrate the following reactions :
(i) Aldol condensation,
(ii) Cannizzaro's reaction.

Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law, with $t_{1 / 2}$ = 3.00 hours. What fraction of sample of surcrose after 8 hours?

Read the following text carefully and answer the questions that follow:
$KMnO _4$ and $K _2 Cr _2 O _7$ are most important chemicals which are used as oxidising agents and disinfectants. $K _2 MnO _4$ is prepared by fusing $MnO _2$ with KOH in presence of $O _2 \cdot K_2 MnO _4$ is electrolysed to get purple coloured $KMnO _4 \cdot Na _2 CrO _4$ is prepared by heating chromite ore with $Na _2 CO _3$ in presence of $O _2 \cdot Na _2 CrO _4$ is converted into $Na _2 Cr _2 O _7$ by reacting with concentrated $H _2 SO _4 \cdot Na _2 Cr _2 O _7$ is reacted with KCl to get $K _2 Cr _2 O _7$, orange coloured solid, soluble in water, changes to yellow coloured $CrO _4^{2-}$ in basic medium, $KMnO _4$ acts as oxidising agent in acidic, neutral as well basic medium. In acidic medium, it converts $Fe ^{2+}$ to $Fe ^{3+}, Sn ^{2+}$ to $Sn ^{4+}, COO ^{-}$to $CO ^2$. In basic medium it converts $I ^{-}$to $IO ^{3-} . K _2 Cr _2 O _7$ acts as oxidising agent only in acidic medium, converts $H _2 S$ to $S , SO _2$ to $SO ^{2-}, I ^{-}$to $I _2$. Lanthanoids and actinoids belong to f-block elements with general electronic configuration $(n-2) f^1$ to $14(n-1) d^{0-2} n s^2$. All actinoids are radioactive. Both show contraction in atomic and ionic radii but actinoid contraction is more than lanthanoid contraction. Lanthanoid show +3 oxidation state, few elements show +2 and +4 oxidation states also. Actinoids show $+3,+4,+5,+6,+7$ oxidation states.
i. Which lanthanoid shows +4 oxidation state and why?
ii. Give two similarities between lanthanoids and actinoids.
iii. Complete the equation and balance:
$
Cr_2 O_7^{2-}+Fe^{2+}+H^{+} \rightarrow ?
$
OR
iii. Convert sodium chromate to sodium dichromate. Give chemical equation.
$2 Na _2 CrO _4+ H _2 SO _4$ (conc.) $\rightarrow$ ?

Read the following text carefully and answer the questions that follow:
Many chemical and biological processes depend on osmosis, the selective passage of solvent molecules through the porous membrane from a dilute solution to a more concentrated one. The osmotic pressure $\pi$ depends on molar concentration of the solution ($\pi$ = CRT). If two solutions are of equal solute concentration and, hence, have the same osmotic pressure, they are said to be isotonic. If two solutions are of unequal osmotic pressures, the more concentrated solution is said to be hypertonic and the more diluted solution is described as hypotonic. Osmosis is the major mechanism, for transporting water upward in the plants. Transpiration is the leaves supports the transport mechanism of water. The osmotic pressure of seawater is about 30 atm; this is the pressure that must be applied to the seawater (separated from pure water using a semi-permeable membrane) to get drinking water.
i. What will happen if a plant cell kept in a hypertonic solution?
ii. Blood cells are isotonic with 0.9% sodium chloride solution. What happens if we place blood cells in a solution containing in 1.2% sodium chloride solution?
iii. What happens when the external pressure applied becomes more than the osmotic pressure of solution?

The rate constant for the first order decomposition of $H_{2}O_{2}$ is given by the following equation: $log~k=14.2-\frac{1.0\times10^{4}K}{T}$. Calculate $E_a$ for this reaction and rate constant k if its half-life period be 200 minute.
( given $R =8.314 J K ^{-1} mol^{-1}$)

What can be inferred from the magnetic moment values of the following complex species?

Example	Magnetic Moment (BM)
$K _4\left[ Mn ( CN )_6\right]$	2.2
$\left[ Fe \left( H _2 O \right)_6\right]^{2+}$	5.3
$K _2\left[ MnCl _4\right]$	5.9

Explain classification of Monohalogen compounds on the basis of $sp^3 (CX)$ bonds.