Real Gases

Q.

What is the physical significance of van der Waals constant a and b?

Q. The value of vanderwaal’s constant ‘a’ for the gases $O_2,N_2,N{H}_{3}andC{H}_4$ are 1.360, 1.390, 4.170 and 2.253 $L^2$ atm $mo{l}^{-2}$ respectively. The gas which can most easily be liquefied is

1. $O_2$
2. $N_2$
3. $N{H}_3$
4. $C{H}_4$

Q. Potassium crystallizes in a body centred cubic lattice. What is the approximate number of unit cells in 4.0 g of potassium? Atomic mass of potassium = 39

Q.

Explain briefly how gases can be liquified?

Q.

What does A and B represent in Van der Waals?

Q.

Pressure versus volume graph for a real gas and an ideal gas are shown in figure. Answer the following question on the basis of this graph.

(i) Interpret the behaviour of real gas with respect to ideal gas at low pressure.

(ii) Interpret the bevaviour of real gas with respect to ideal gas at high pressure.

(iii) Mark the pressure and volume by drawing a line at the point where real gas behaves as an ideal gas.

Q.

A certain gas obeys $\mathrm{P}({\mathrm{V}}_{\mathrm{m}}-\mathrm{b})=\mathrm{RT}$. The value of${\left(\frac{\partial \mathrm{Z}}{\partial \mathrm{P}}\right)}_T$is $\frac{\mathrm{xb}}{\mathrm{RT}}$. The value of $\mathrm{x}$is_________.

Q.

State two conditions necessary to liquefy a gas.

Q. 2gm of $O_2$ at ${27}^{\circ }$C and 760mm of Hg pressure has volume

1. 2.8 lit.
2. 11.2 lit.
3. 22.4 lit.
4. 1.5 lit.

Q.

Why pressure of real gas is less than ideal gas?

Q. $50\text{ml}$ of a mixture of $N{H}_3$ and $H_2$ was completely decomposed by sparking into nitrogen and hydrogen. $40\text{ml}$ of oxygen was added and the mixture was sparked again. After cooling to the room temperature, the mixture was shaken with alkaline pyrogallol solution and a contraction of $6\text{ml}$ was observed. Calculate the % by volume of $N{H}_3$ in the original mixture.

1. 27%
2. 72%
3. 36%
4. 54%

Q.

Under what conditions gases can be liquefied?

Q. Dry air was successively passed through a solution of 5g solute in 80 g water and then through pure water. The loss in weight of solution was 2.5g and that of pure water was 0.04g. The mol. wt. of solute is

Q. The gases that show positive deviation at all pressures at 273 K from ideal gas equation among the following is/are

1. $H_2$
2. $N_2$
3. both a and b
4. $He$

Q.

London forces are also known as__________

Q.

For real gases the relation between, P, V and T is given by van der Waals' equation

$(P+\frac{a{n}^2}{V^2})(V-nb)=nRT$

where 'a' and 'b' are van der Waals' constants, 'nb' is approximately equal to the total volume of the molecules of a gas. 'a' is the measure of the magnitude of intermolecular attraction.

(i) Arrange the following gases in the increasing order of 'b' Give reason.

$O_2,C{O}_2,H_2,He$

(ii) Arrange the following gases in the descending order of magnitude of 'a'. Give reason.

$C{H}_4,O_2,H_2$

Q. A compound alloy of gold and copper crystallizes in a cubic lattice in which the gold atoms occupy the corners of a cube, and the copper atoms occupy the centers of each of the faces of the cube. The formula of this compound is:

1. $AuCu$
2. $AuC{u}_2$
3. $AuC{u}_3$
4. $A{u}_{3}Cu$

Q.

Explain the physical significance of Van der Waals parameters.

Q. Volume strength of perhydrol is

1. 30
2. 60
3. 100
4. 11.2

Q.

What is Most Important about Kinetic Molecular Theory?

Q. Silver (atomic weight = 108 g/mol) has a density of $5/\pi gc{m}^{-3}$. The number of silver atoms on a surface of area $1.35\times {10}^{-14}{m}^2$ can be expressed in scientific notation as $y\times {10}^x$. The value of $(x+y)$ is
(Take $N_A=6.0\times {10}^{23}$ and the value of $\pi =3$)

Q. 200 ml 0.1M K2SO4 is added with 300ml 0.2MKCl .determine molarconcentration of k+ in the solution.

Q. Which of the following gases will have density 1.8 g/L at 760 torr pressure and ${27}^{\circ }$C ?

1. $N{H}_3$
2. $O_2$
3. $C{O}_2$
4. $S{O}_2$

Q. The pair of isochoric processes among the transformation of states is

1. M to N and N to K
2. L to M and M to N
3. K to L and L to M
4. L to M and N to K

Q.

The relation between pressure exerted byan ideal gas $\left(p_{ideal}\right)$ and observed pressure $\left(p_{real}\right)$ is given by the equation,

$P_{ideal}=P_{real}+\frac{a{n}^2}{V^2}$

(i) If pressure is taken in $N{m}^{-2}$ , number of moles in mol and volume in $m^3$, calculate the unit of 'a'.

(ii) What will be unit of 'a' when pressure is in atmosphere and volume in$d{m}^3$?

Q.

The rate of cooling at $600K$, if the surrounding temperature is $300K$, is $H$. The rate of cooling at $900K$ is

1. $\frac{16}{3}H$

2. $2H$

3. $3H$

4. $\frac{2}{3}H$

Q. Assertion :Van der Waals' constant ${}^{\prime }{a}^{\prime }$ depends on the intermolecular force. Reason: Van der Waals' constant ${}^{\prime }{b}^{\prime }$ depends on the radius of gas molecule.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q.

The $8.9\mathrm{M}$ ${\mathrm{H}}_2{\mathrm{O}}_2$at $273\mathrm{K}$ and $1\mathrm{atm}$ its volume strength will be$—$$\left(\mathrm{R}=0.0821{\mathrm{LatmK}}^{-1}{\mathrm{mol}}^{-1}\right)$(Round it off to the nearest integer)

Q.

Under which of the following conditions applied together, a gas deviates most from the ideal hevaviour?

(a) Low pressure (b) High pressure

(c) Low temperature (d) High temperature

Q. Solubility order of csF lif kf naf rbf