Factors Affecting Vapour Pressure

Q. $p_A$ and $p_B$ are the vapour pressures of pure liquid components, $A$ and $B$, respectively of an ideal binary solution. If $x_A$ represents the mole fraction of component $A$, the total pressure $\left(P\right)$ of the solution will be:

1. $p_A+x_A(p_B-p_A)$
2. $p_A+x_A(p_B-p_A)$
3. $p_B+x_A(p_B-p_A)$
4. $p_B+x_A(p_A-p_B)$

Q. The vapour pressure of a solvent $A$ is $0.80atm$. When a non-volatile substance $B$ is added to this solvent its vapour pressure drops to $0.6atm$, the mole fraction of $B$ in the solution is

1. 0.5
2. 0.25
3. 0.75
4. 0.9

Q. Vapour pressure of solution containing $6\text{g}$ of a non-volatile solute in $180\text{g}$ of water is $20\text{torr}$. If $1$ mole water is further added, then vapour pressure increases by $0.02\text{torr}$. Which of the following is not correct?

1. The molecular weight of solute is $55{\text{g mol}}^{-1}$
2. The vapour pressure of pure water is $20.22\text{torr}$
3. Addition of more water in the solution will further raise the vapour pressure of the solution
4. The vapour pressure of pure water is $22.22\text{torr}$

Q. If vapour pressure of pure liquid $A$ is $100\text{mm Hg}$ and Vapour pressure of pure liquid $B$ is $150\text{mm Hg}$. $2$ mole of liquid $A$ and $3$ mole of liquid $B$ are mixed to form an ideal solution. The vapour pressure of solution will be:

1. $135\text{mm}$
2. $130\text{mm}$
3. $140\text{mm}$
4. $145\text{mm}$

Q.

How can the boiling point of a liquid be raised, without adding any impurity?

Q.

Ethyl alcohol has a higher boiling point than water.

1. True
2. False

Q.

The vapour pressure of the water depends upon?

Q. $P_A$ and $P_B$ are the vapour pressures of pure liquid components, $A$ and $B$, respectively of an ideal binary solution. If $x_A$ represents the mole fraction of component $A$, the total pressure of the solution will be:
[1 mark]

1. $P_A+x_A(P_B-P_A)$
2. $P_A+x_A(P_A-P_B)$
3. $P_B+x_A(P_B-P_A)$
4. $P_B+x_A(P_A-P_B)$

Q. What is the relation between osmotic pressure and elevation in boiling point

Q. Two liquids $A$ and $B$ have vapour pressure in the ratio $P_A^{\circ }:P_B^{\circ }=1:3$ at a certain temperature. Assume $A$ and $B$ form an ideal solution and the ratio of mole fractions of $A$ to $B$ in the vapour phase is $4:3$. Then the mole fraction of $B$ in the solution at the same temperature is:

1. $\frac{1}{5}$
2. $\frac{2}{3}$
3. $\frac{4}{5}$
4. $\frac{1}{4}$

Q. The order of volatility of liquids A, B, C, D is A > C > B > D. The order of their vapour pressure is:

1. A
2. B
3. C
4. D

Q. For a binary ideal solution of two volatile liquids A and B (assuming B is more volatile), correct option which may be observed during mixing of these two liquids A and B (symbols hold their usual meaning)

1. $P_{total}<P_A^0$
2. Mole fraction of A in vapour state will increase with increase in $X_A$
3. $P_B$ decreases with increase in $X_B$
4. $P_A$ increases with increase in $X_B$

Q. When temperature increases, intermolecular forces decreases.

1. True
2. False

Q. $P_A^0$ and $P_B^0$ are the vapour pressure of pure liquid components, $A$ and $B$, respectively of an ideal binary solution. If $X_A$ represents the mole fraction of component $A$, the total pressure of the solution will be:

1. $P_B^0+X_A(P_B^0-P_A^0)$
2. $P_B^0+X_A(P_A^0-P_B^0)$
3. $P_A^0+X_A(P_B^0-P_A^0)$
4. $P_A^0+X_A(P_A^0-P_B^0)$

Q. ntat normal temp and pressure 0.24 g volatile subs produces 43ml vapour , . then vapour density of subs will be [demsity of hydrogen =0.000089g/mln

Q. A liquid is transferred from a smaller vessel to a bigger vessel (with bigger surface area) at the same temperature. What will be the effect on vapour pressure?

1. \N
2. Decreases
3. Increases
4. Remains same

Q. Mixture of volatile components of A and B has total vapour presssure (in torr) P=254-119Xa, where Xa is the mole fraction of component A in mixture . hence pure vapour pressure of A and B (in torr)

Q. Paragraph for below question
नीचे दिए गए प्रश्न के लिए अनुच्छेद

The vapour pressure of two pure liquids A and B which forms an ideal solution are 400 torr and 800 torr respectively at 300 K. A liquid solution of A and B with mole fraction of 0.5 each is contained in a cylinder closed by a piston on which the pressure can be varied. The solution is slowly vaporized at 300 K by decreasing the applied pressure.

300 K पर आदर्श विलयन बनाने वाले दो शुद्ध द्रवों A तथा B के वाष्प दाब क्रमशः 400 टोर तथा 800 टोर हैं। A तथा B प्रत्येक के 0.5 मोल प्रभाज वाले द्रव विलयन को पिस्टन से बंद किए गए सिलेण्डर में भरा गया है जिस पर दाब परिवर्तित हो सकता है। 300 K पर प्रयुक्त दाब घटाने पर विलयन धीरे-धीरे वाष्पीकृत होता है।

Q. The composition of vapour when first bubble of gas is formed. [Y_A and Y_B are mole fraction of A and B in gaseous phase]

प्रश्न - जब गैस का प्रथम बुलबुला बनता है, तो वाष्प का संघटन है [Y_A तथा Y_B गैसीय प्रावस्था में A तथा B के मोल प्रभाज हैं]

1. $Y_A=\frac{1}{3}$ and $Y_B=\frac{2}{3}$
   
   $Y_A=\frac{1}{3}$ तथा $Y_B=\frac{2}{3}$
2. Y_A = 0.5 and Y_B = 0.5
   
   Y_A = 0.5 तथा Y_B = 0.5
3. $Y_A=\frac{2}{3}$ and $Y_B=\frac{1}{3}$
   
   $Y_A=\frac{2}{3}$ तथा $Y_B=\frac{1}{3}$
4. $Y_A=\frac{1}{4}$ and $Y_B=\frac{3}{4}$
   
   $Y_A=\frac{1}{4}$ तथा $Y_B=\frac{3}{4}$

Q.

Does vapour pressure change with temperature?

Q. When a bottle of cold drink is opened, the gas comes out with a fizze due to :

1. decrease in temperature
2. increase in pressure
3. decrease in pressure suddenly which results in decrease of solubility of $C{O}_2$ gas in water
4. none

Q. The vapour pressure of a solution of a non- volatile solute $B$ in a solvent $A$ is $95\%$ of the vapour pressure of the pure solvent at the same temparature. If the molecular weight of the solvent is $0.3$ times the molecular weight of the solute, what is the ratio of the weight of solvent to solute?

1. $0.15$
2. $5.7$
3. $0.2$
4. None of these

Q. The modified barometer which is used to measure pressure exerted by a gas is called:

1. Spyrobarometer
2. Manometer
3. Spyrometer
4. Cathetometer

Q. The vapour pressure of pure liquid solvent A is 0.80 atm. When a nonvolatile substance B is added to the solvent its vapour pressure drops to 0.60 atm. What is the mole fraction of component B in the solution?( If your answer is $x$, then write $x\times 100$).

Q. Temperatures of liquids A, B, C, D are 25, 50, 75, 90 (${}^{0}C$) respectively. Order of their vapour pressures is:

1. A
2. B
3. C
4. D

Q. Molecular mass of a volatile organic solid can be determined by :

1. Silver chloride method
2. Platinic chloride method
3. Victor Mayers method
4. Kjeldahls method

Q. What does the following statement mean? "A liquid having weaker interparticle forces has higher vapour pressure."

Q. At 363 K , the vapour pressure of A is $21kPa$ and that of b is $18kPa$. 1 mol of A and 2 moles of B are mixed . Assuming that this solution is ideal , the vapour pressure of the mixture in $kPa$ rounded off to the Nearest Integer is

Q. Liquid M and liquid N form an ideal solution. The vapour
pressures of pure liquids M and N are 450 and 700 mmHg,
respectively, at the same temperature. Then correct statement
is:
$x_M$ = mole fraction of M in solution;
$x_N$ = mole fraction of N in solution;
$y_M$ = mole fraction of M in vapour phase;
$y_N$ = mole fraction of N in vapour phase

1. $\frac{x_M}{x_N}<\frac{y_M}{y_N}$
2. $(x_M-y_M)<(x_N-y_N)$
3. $\frac{x_M}{x_N}=\frac{y_M}{y_N}$
4. $\frac{x_M}{x_N}>\frac{y_M}{y_N}$

Q. 100 ml each of coconut oil and water are taken in two beakers and kept in the freezer.
a. What difference can be observed in their volumes during freezing?
b. What do you infer from the observation?
c. When water is frozen in glass bottles, it is advised not to fill the bottles completely. Explain the reason.

Q. The diffusion coefficient of an ideal gas is proportional to its mean free path and mean speed. The absolute temperature of an ideal gas is increased 4 times and its pressure is increased 2 times. As a result, the diffusion coefficient of this gas increases $x$ times. The value of $x$ is:___