Entropy

Q.

Entropy is a state function.

1. False

2. True

Q.

Calculate the change in entropy for the following reaction
$2CO\left(g\right)+O_2\left(g\right)\to 2C{O}_2\left(g\right)$.
Given $S_{C{O}_2}^0=213.6J{K}^{-1}mo{l}^{-1}$, $S_{CO}^0=297.6J{K}^{-1}mo{l}^{-1}$ respectively.

1. None of these

2. -185.03 $J{K}^{-1}mo{l}^{-1}$

3. -143.03 $J{K}^{-1}mo{l}^{-1}$

4. -173.03 $J{K}^{-1}mo{l}^{-1}$

Q.

Entropy change in a cyclic process is zero.

1. True

2. False

Q. For the reaction $\frac{1}{2}{N}_2\left(g\right)+\frac{3}{2}{H}_2\left(g\right)\to N{H}_3\left(g\right);\Delta H=-30kJ$ to be at equilibrium at ${477}^{\circ }C$. If standard entropy of $N_2\left(g\right)$ and $N{H}_3\left(g\right)$ are $60$ and $50Jmol{e}^{-1}{K}^{-1}$ respectively then calculate the standard entropy of $H_2\left(g\right)$ in $Jmol{e}^{-1}{K}^{-1}$.

Q. Match the transformations in Column I with appropriate options in Column II.
(2011)

	Column I		Column II
A.	$C{O}_2\left(s\right)\to C{O}_2\left(g\right)$	p.	Phase transition
B.	$CaC{O}_3\left(s\right)\to CaO\left(s\right)$	q.	Allotropic change
C.	$2H\bullet \to H_2\left(g\right)$	r.	$△$H is positive
D.	$P_{(white,solid)}\to P_{(red,solid)}$	s.	$△$ S is positive
		t.	$△$ S is negative

1. A-p, s;
   B-r;
   C-q, t;
   D-p, t
2. A- s;
   B-r, s;
   C-t;
   D-q, t
3. A-p, r, s;
   B-r, s;
   C-q, t;
   D-p, q, t
4. A-p, r, s;
   B-r, s;
   C-t;
   D-p, q, t

Q. Which of the following processes is an iso-entropic process?

1. Isothermal process

2. Adiabatic process

3. Isobaric process

4. Isochoric process

Q. Fo an ideal gas, consider only P-V work in going from initial state X to the final state Z. The final state Z can be reached by either of the two paths shown in the figure.

[Take $△$ S as change in entropy and W as work done].
Which of the following choice(s) is (are) correct?
(2012)

1. $△S_{X\to Z}=△S_{X\to Y}+△S_{Y\to Z}$
2. $W_{X\to Z}=W_{X\to Y}+W_{Y\to Z}$
3. $W_{X\to Z△Z}=W_{X\to Y}$
4. $△S_{X\to Y\to Z}=△S_{X\to Y}$

Q. Calculate the change of entropy ${\Delta }_r{S}_m^{\circ }$ at 298 K for the reaction in which urea is formed from $N{H}_3$ and $C{O}_2$. The standard entropy of $N{H}_{2}CON{H}_2$ is 174.0 $J{K}^{-1}mo{l}^{-1}$. For $N{H}_3$, $C{O}_2$ and $H_{2}O$ it is 192.3, 213 and 69.9$J{K}^{-1}$

1. 
2. 354.4 JK
3. 453.4
4. 273 JK

Q. For the process, $H_{2}O\left(l\right)\to H_{2}O\left(g\right)atT={100}^{\circ }C$ and 1 atmosphere pressure, the correct choice

1. $\Delta S_{system}>0and\Delta S_{surrounding}>0$
2. $\Delta S_{system}<0and\Delta S_{surrounding}>0$
3. $\Delta S_{system}<0and\Delta S_{surrounding}<0$
4. $\Delta S_{system}>0and\Delta S_{surrounding}<0$

Q. The normal boiling point of a liquid $X$ is 400 K. $\Delta H_{vap}$ at normal boiling point is 40 kJ/mol.
Correct statement(s) is/are:

1. $\Delta S_{vaporisation}<100\text{J/mol k}$ at 400 K and 2 atm
2. $\Delta S_{vaporisation}<10\text{J/mol k}$ at 400 K and 1 atm
3. $\Delta G_{vaporisation}<0$ at 410 K and 1 atm
4. $\Delta U=43.32\text{kJ/molK}$ at 400 K and 1 atm