Entropy of Phase Change

Q. The entropy change involved in the conversion of 1 mole of liquid water at $373K$ to vapour will be:
Given: $△H_{vap}=2.257kJ/g$

1. $150J{K}^{-1}mo{l}^{-1}$
2. $130.6J{K}^{-1}mo{l}^{-1}$
3. $118.5J{K}^{-1}mo{l}^{-1}$
4. $108.9J{K}^{-1}mo{l}^{-1}$

Q.

The standard molar entropy of $H_{2}O$ (1) is 70 $J{K}^{-1}$ $mo{l}^{-1}$. Will the standard molar entropy of $H_{2}O$(s) be more, or less than 70 $J{K}^{-1}$ $mo{l}^{-1}$?

Q. Entropy change involved in conversion of one mole of liquid water at $373K$ to vapour at the same temperature (latent heat of vaporisation of water $=2.257kJ{g}^{-1})$.

1. $30.7J{K}^{-1}mo{l}^{-1}$
2. $60.3J{K}^{-1}mo{l}^{-1}$
3. $9.8J{K}^{-1}mo{l}^{-1}$
4. $108.9J{K}^{-1}mo{l}^{-1}$

Q. The free energy and entropy change in kJ per mole when liquid water boils at atmospheric pressure are respectively (latent heat of water = 2.0723 kJ $g^{-1}$)

1. 0, 0
2. 0.1, 0.1
3. 0.1, 0
4. 0, 0.1

Q. The enthalpy of vaporization of water at ${100}^{o}C$ is $40.63kJmo{l}^{-1}$. It's entropy change for the vaporization would be :

1. $406.3J{K}^{-1}mo{l}^{-1}$
2. $108.9J{K}^{-1}mo{l}^{-1}$
3. $108.9kJ{K}^{-1}mo{l}^{-1}$
4. $4063kJ{K}^{-1}mo{l}^{-1}$

Q. If $△H_{vaporisation}$ of substance $X\left(l\right)$ (molar mass : 30 g/mol) is 300 J/g at it's boiling point 300 K, then molar entropy change for reversible condensation process is

1. None of these
2. $30J/mol{K}^{-1}$
3. $-60J/mol{K}^{-1}$
4. $-30J/mol{K}^{-1}$

Q. Change in entropy $\left(\text{in J/K}\right)$ for freezing of $10\text{g}$ of $H_{2}O\left(l\right)$ (enthalpy of fusion is $80\text{cal/g}$) at $0^{\circ }\text{C}$ and $1\text{atm}$ is:
(Given: $1\text{cal}=4.2\text{J}$, Round the answer upto one decimal point)

1. $24.6\text{J/K}$
2. $12.3\text{J/K}$
3. $18.5\text{J/K}$
4. $9.2\text{J/K}$

Q.

Does Entropy increase with volume?

Q. Predict in how many of the following processes entropy change of the system is positive .
(i) $CaC{O}_3\left(s\right)\to CaO\left(s\right)+C{O}_2\left(g\right)$
(ii) $N_2\left(g\right)+3H_2\left(g\right)\to 2N{H}_3\left(g\right)$
(iii) $HCl\left(g\right)+N{H}_3\left(g\right)\to N{H}_{4}Cl\left(s\right)$
(iv) $2S{O}_2\left(g\right)+O_2\left(g\right)\to 2S{O}_3\left(g\right)$
(v) Cooling of $N_2\left(g\right)$ from ${20}^{o}Cto-{50}^{o}C$

1. 2
2. In all the processess
3. 3
4. 1

Q. Calculate the change in entropy when 1 mol of solid iodine at a temperature of 360 K is heated at constant pressure to produce liquid iodine at a temperature of 410 K. The constant pressure molar heat capacity of solid iodine is 54.44 J $K^{-1}$ $mo{l}^{-1}$ and liquid iodine is 80.67 J $K^{-1}$ $mo{l}^{-1}$.
The melting point of iodine is 387 K and molar enthalpy of fusion of iodine is 7.87 kJ/mol.

1. 8.6 $J{K}^{-1}$ $mo{l}^{-1}$
2. 28.9 $J{K}^{-1}$ $mo{l}^{-1}$
3. 20.3 $J{K}^{-1}$ $mo{l}^{-1}$
4. 11.7 $J{K}^{-1}$ $mo{l}^{-1}$

Q. At 373 K, steam and water are in equilibrium and ${△}_{vap}H=40.98kJmo{l}^{-1}.$ What will be entropy change for conversion of water into steam?
$H_2{O}_{\left(l\right)}\to H_2{O}_{\left(g\right)}$

1. $109.8J{K}^{-1}mo{l}^{-1}$
2. $31J{K}^{-1}mo{l}^{-1}$
3. $21.98J{K}^{-1}mo{l}^{-1}$
4. $326J{K}^{-1}mo{l}^{-1}$

Q. If latent heat of fusion of ice is $80\text{cal}$ per mole at $0{}^{\circ }C$, calculate molal depression constant for water.

1. $0.1863{\text{K kg mol}}^{-1}$
2. $1.863{\text{K kg mol}}^{-1}$
3. $186.3{\text{K kg mol}}^{-1}$
4. $18.63{\text{K kg mol}}^{-1}$

Q.

1. $+540.3$
2. $+727.3$
3. $-166.9$
4. $+9.8$

Q. Predict in how many of the following processes entropy change of the system is positive .
(i) $CaC{O}_3\left(s\right)\to CaO\left(s\right)+C{O}_2\left(g\right)$
(ii) $N_2\left(g\right)+3H_2\left(g\right)\to 2N{H}_3\left(g\right)$
(iii) $HCl\left(g\right)+N{H}_3\left(g\right)\to N{H}_{4}Cl\left(s\right)$
(iv) $2S{O}_2\left(g\right)+O_2\left(g\right)\to 2S{O}_3\left(g\right)$
(v) Cooling of $N_2\left(g\right)$ from ${20}^{o}Cto-{50}^{o}C$

1. In all the processess
2. 3
3. 1
4. 2

Q. Calculate the enthalpy of vaporisation (in $kJ/mol$) for ethanol. Given, entropy change for the process is $109J{K}^{-1}mo{l}^{-1}$ and boiling point of ethanol is $78.5{}^{o}C.$

Q. Entropy change involved in conversion of one mole of liquid water at $373K$ to vapour at the same temperature (latent heat of vaporisation of water $=2.257kJ{g}^{-1})$.

1. $30.7J{K}^{-1}mo{l}^{-1}$
2. $60.3J{K}^{-1}mo{l}^{-1}$
3. $9.8J{K}^{-1}mo{l}^{-1}$
4. $108.9J{K}^{-1}mo{l}^{-1}$

Q. At $0^{o}C$, if enthalpy of fusion of ice is 1365 kcal/mol, the molar entropy change for melting of ice at $0^{o}C$ is?

Q. Enthalpy of fusion of water is $6.01kJ{mol}^{-1}$. The entropy change of $1$ mole of ice at its melting point will be:

1. $44kJ{mol}^{-1}$
2. $22kJ{mol}^{-1}$
3. $109kJ{mol}^{-1}$
4. $11kJ{mol}^{-1}$

Q. The enthalpy of vaporisation of liquid diethyl ether $(C_2{H}_5{)}_{2}O$ is $26kJmo{l}^{-1}$ at its boiling point ${35}^{o}C.$ Calculate $△S^o$ for conversion of vapour to liquid (condensation) at ${35}^{o}C.$

1. $-84.41{\text{J K}}^{-1}{\text{mol}}^{-1}$
2. $+84.41{\text{J K}}^{-1}{\text{mol}}^{-1}$
3. $-48.41{\text{J K}}^{-1}{\text{mol}}^{-1}$
4. $+48.41{\text{J K}}^{-1}{\text{mol}}^{-1}$

Q. The enthalpy of vaporisation of liquid diethyl ether $(C_2{H}_5{)}_{2}O$ is $26{\text{kJ mol}}^{-1}$ at its boiling point $35{}^o\text{C}.$ Calculate $△S^o$ for conversion of vapour to liquid (condensation) at $35{}^o\text{C}.$

1. $-84.41{\text{J K}}^{-1}{\text{mol}}^{-1}$
2. $+84.41{\text{J K}}^{-1}{\text{mol}}^{-1}$
3. $-48.41{\text{J K}}^{-1}{\text{mol}}^{-1}$
4. $+48.41{\text{J K}}^{-1}{\text{mol}}^{-1}$

Q. Ethanol boils at ${78.4}^{o}C$ and the enthalpy of vaporisation of ethanol is $42.4kJmo{l}^{-1}$ . What will be the entropy of vaporisation of ethanol:

1. $101.5J{K}^{-1}mo{l}^{-1}$
2. $150J{K}^{-1}mo{l}^{-1}$
3. $120.66J{K}^{-1}mo{l}^{-1}$
4. $135J{K}^{-1}mo{l}^{-1}$

Q. Calculate the entropy change when 1 mol of ice $0^{\circ }C$ is converted into water at $0^{\circ }C$. The change in heat is 1436 cal per mol.

1. 
2. 

3. 

4. None of these

Q. Calculate the change in entropy for fusion of 1 mole of ice. The melting point of ice is 273 K and molar enthalpy of fusion for ice = 6.0 kJ $mol{e}^{-1}$

1. $△S_f$ =21.97 $J{K}^{-1}mo{l}^{-1}$
2. $△S_f$ =21.87 $J{K}^{-1}mo{l}^{-1}$
3. $△S_f$ =21.78 $J{K}^{-1}mo{l}^{-1}$
4. $△S_f$ =21.79 $J{K}^{-1}mo{l}^{-1}$

Q. If enthalpy of vaporisation of water is $186.5kJ/mol$, the entropy of its vaporisation will be:

1. $1.5$
2. $1.0$
3. $2.0$
4. $0.5$

Q. Entropy change involved in conversion of one mole of liquid water at $373K$ to vapour at the same temperature (latent heat of vaporisation of water $=2.257kJ{g}^{-1})$.

1. $30.7J{K}^{-1}mo{l}^{-1}$
2. $60.3J{K}^{-1}mo{l}^{-1}$
3. $9.8J{K}^{-1}mo{l}^{-1}$
4. $108.9J{K}^{-1}mo{l}^{-1}$

Q. At ${40}^{o}C$, the vapour pressure in torr of methanol and ethanol solution is $P=119x+135$. Here, $x$ is the mole fraction of methanol. Hence, _______________ .

1. vapour pressure of equimolar mixture of each is 127mm
2. mixture is completely immiscible
3. vapour pressure of pure ethanol is 135 torr
4. vapour pressure of pure methanol is 119 torr

Q. For a liquid, enthalpy of fusion is $1.435kcal{mol}^{-1}$ and molar entropy change is $5.26cal{mol}^{-1}{K}^{-1}$. The melting point of the liquid is:

1. ${-273}^{o}C$
2. ${173}^{o}K$
3. ${100}^{o}C$
4. $0^{o}C$

Q.

During which of the following processes, does Entropy decrease ?

$ \left(a\right)$ Freezing of water to ice at $ {0}^{°} c$

$ \left(b\right)$ Freezing of water to ice at $ -{10}^{° } C$

$ \left(c\right)$

$ \left(d\right)$ Adsorption of $ CO\left(g\right)$ on lead surface.

$ \left(e\right)$ Dissolution of $ NaCl$ in water

Q.

Calculate entropy change for vaporization of 1 mole of liquid water to steam at ${100}^{\circ }C$ if $\Delta H_v$=40.8 kJ $mo{l}^{-1}$.

1. $\Delta S_v=107.38J{K}^{-1}mo{l}^{-1}$

2. $\Delta S_v=109.48J{K}^{-1}mo{l}^{-1}$

3. $\Delta S_v=109.38J{K}^{-1}mo{l}^{-1}$

4. $\Delta S_v=107.38J{K}^{-1}mo{l}^{-1}$

Q. Calculate the change in entropy for fusion of 1 mole of ice. The melting point of ice is 273 K and molar enthalpy of fusion for ice = 6.0 kJ $mol{e}^{-1}$

1. $△S_f$ =21.97 $J{K}^{-1}mo{l}^{-1}$
2. $△S_f$ =21.87 $J{K}^{-1}mo{l}^{-1}$
3. $△S_f$ =21.78 $J{K}^{-1}mo{l}^{-1}$
4. $△S_f$ =21.79 $J{K}^{-1}mo{l}^{-1}$