Liquefaction of Gases and Critical Constants

Q.

What is STP in chemistry?

Q.

Why is $22.4$ liters called the molar volume of a gas?

Q.

A soft drink was bottled with a partial pressure of CO₂

A soft drink was bottled with a partial pressure of CO₂ of 3 bar over the liquid at room temperature. The partial pressure of CO₂ over the solution approaches a value of 30 bar when 44 g of CO₂ is dissolved in 1 kg of water at room temperature. The approximate pH of the soft drink is ______ × 10^–1

(First dissociation constant of H₂CO₃= 4.0 × 10^–7; log 2 = 0.3; density of the soft drink= 1 g mL^–1)

Q.

Critical temperature and critical pressure values of four gases are given

Gas	C. Temp(K)	C.pressure(atm)
P	5.1	2.2
Q	33	13
R	126	34
S	135	40

Which of the gas/gases cannot be liquefied at a temperature of 100 K and a pressure of 50 atmospheres?

1. P only
2. S only
3. R and S
4. P and Q

Q.

Critical temperature for carbon dioxide and methane are ${31.1}^{\circ }C$ and $–{81.9}^{\circ }C$ respectively. Which of these has stronger intermolecular forces and why?

Q. At 100^o C and 1 atm, if the density of liquid water is 1.0 g/cm³ and that of water vapour is 0.0006 g/m³ , then the volume occupied by water molecules in 1 litre of steam at that temperature is

1. 6 cm³
2. 0.6 cm³
3. 60 cm³
4. 0.06 cm³

Q. What is the correct increasing order of a gas being liquifiable?

1. $H_2<N_2<C{H}_4<C{O}_2$
2. $H_2<C{O}_2<C{H}_4<N_2$
3. $C{O}_2<C{H}_4<N_4<H_2$
4. $C{O}_2<C{H}_4<H_2<N_2$

Q. If the critical temperature of a gas is $27{}^{\circ }C$ then it's inversion temperature will be:

1. ${2252}^{}K$
2. $2752K$
3. $1752K$
4. ${2025}^{}K$

Q. Which of the following is correct for critical temperature?

1. It is the highest temperature at which liquid and vapour can
   co-exist.
2. Beyond this temperature, a gas cannot be liquefied by compression.
3. At this temperature, the surface tension of the system is zero.
4. At this temperature, the gas and the liquid phases have different critical densities.

Q.

Isotherms of carbon dioxide at various temperatures are represented in figure. Answer the following based on this figure.

(i) In which state will $C{O}_2$ exist between the points a and b at temperature $T_1$ ?

(ii) At what point will $C{O}_2$ start liquefying when temperature is $T_1$?

(iii) At what point will $C{O}_2$ be completely liquefied when temperature is (T_2\)

(iv) Will condensation take place when the temperature is $T_3$?

(v) What portion of the isotherm at $T_1$ represent liquid and gaseous $C{O}_2$ at equilibrium?

Q. The van der Waal gas constant 'a' is given by which of the following relations?

1. $\frac{V_c}{3}$
2. $\frac{R{T}_c}{8P_c}$
3. $9R{T}_c{V}_c$
4. $3P_c{V}_c^2$

Q.

The temperature above which gas cannot be liquefied by application of pressure alone is

1. Critical temperature

2. None of the above

3. Boyle temperature

4. Curie temperature

Q.

The critical temperature $\left(T_c\right)$ and critical pressure $p_c)$ of $C{O}_2$ are ${30.98}^{\circ }C$ and 73 atm respectively.Can $C{O}_2$ (g) be liquefied at ${32}^{\circ }C$ and 80 atm pressure?

Q. For a real gas the P-V curve was experimentally plotted and it had the following appearance. With respect to liquefaction. Choose the correct statement

1. At $T=500K$, $P=40atm$, the state will be liquid
2. At $T=300K$, $P=50atm$, the state will be gas
3. At $T<300K$, $P=20atm$, the state will be gas
4. At $300K<T<500K,P>50atm$, the state will be liquid

Q.

Isotherms of carbon dioxide gas are shown in figure. Mark a path for changing gas into liquid such that only one phase (i.e., either a gas or a liquid) exists at any time during the change. Explain how the temeprature, volume and pressure should be changed to carry out the change?

Q.

8. Tiny drops of water are called __________.

Q.

If $pv=81$, then $\frac{dp}{dv}$ at $v=9$ is equal to

1. $1$

2. $-1$

3. $2$

4. None of these

Q. van der Waals' constants of two gases $X$ and $Y$ are as given:
$\begin{array}{ccc}& a\left(L^{2}atm{\text{mol}}^{-2}\right)& b\left({\text{L mol}}^{-1}\right)\\ \text{Gas}X& 5.6& 0.065\\ \text{Gas}Y& 5.1& 0.012\end{array}$
Which option is true?

1. $T_c\left(X\right)>T_c\left(Y\right)$
2. $T_c\left(X\right)=T_c\left(Y\right)$
3. $V_c\left(X\right)>V_c\left(Y\right)$
4. $V_c\left(Y\right)>V_c\left(X\right)$

Q.

One of the assumptions of kinetic theory of gases states that "there is no force of attraction between the molecules of a gas." How far is this statement correct? Is it possible to liquefy an ideal gas? Explain.

Q. Assertion (A): Gases do not liquefy above their critical temperature, even on applying high pressure.
Reason (R): Above critical temperature, the molecular speed is high and intermolecular attractions cannot hold the molecules together because they escape because of high speed.

1. Both A and R are true and R is the correct expalanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Q.

In the following question a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below in each question.

Assertion (A) Gases do not liquefy above their critical temperature, even on applying high pressure.

Reason (R) Above critical temperature, the molecular speed is high and intermolecular attractions cannot hold the molecules together because they escape because of high speed.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

Q. The value of van der Waals' constant $a$ for various gases are given
$\begin{array}{cc}\text{Gas}& a\left(L^{2}atmmo{l}^{-2}\right)\\ N_2& 1.390\\ O_2& 1.360\\ N{H}_3& 4.170\\ C{H}_4& 2.253\end{array}$
The order of liquefaction of these gases is

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

Q.

$H_2$ gas is adsorbed on activated charcoal to a very little extent in comparison to easily liquefiable gases due to ____________.

1. very strong van der Waal’s interaction.

2. very high critical temperature.

3. very weak van der Waals forces.

4. very low critical temperature.

Q. The vander waals constant for gases $A,B$ and $C$ are as follows:

$\begin{array}{ccc}\text{Gas}& {\text{a/dm}}^6{\text{kPa mol}}^{-2}& {\text{b/dm}}^3{\text{mol}}^{-1}\\ A& 405.3& 0.027\\ B& 1215.9& 0.030\\ C& 607.95& 0.032\end{array}$

Which gas has highest critical temperature :

1. $B$
2. $C$
3. All have same critical temperature.
4. $A$

Q.

The critical temperatures of ${\mathrm{CO}}_2$ gas and ${\mathrm{N}}_2$ gas are ${31}^{\mathrm{o}}\mathrm{C}$and $-{147}^{\mathrm{o}}\mathrm{C}$, respectively. Which gas is liquefied easily and why?

Q.

The temperature at which a real gas obeys the ideal gas laws over a fairly wide range of pressure is _____.

1. Critical temperature

2. Inversion temperature

3. Boyle's temperature

4. Reduced temperature

Q. Chlorine is more easily liquefied than ethane because ("a” and "b" are van der waals constants for gases), a for $C{l}_2$ is a for $C_2{H}_6$ but b for $C{l}_2$ is a for $C_2{H}_6$

1. greater than
2. lesser than
3. equal to
4. equal to

Q.

Why chlorination is faster than bromination?

Q.

Give reason for the following:

The boiling point of tap water is above 100 °C.

Q. What is boyle temperature?