Entropy

Q.

Briefly explain the thermodynamic processes.

Q. For micelle formation, which of the following
statements are correct?
A. Micelle formation is an exothermic process.
B. Micelle formation is an endothermic process.
C. The entropy change is positive
D. The entropy change is negative

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

Q.

Why is entropy always increasing?

Q.

Which of the following is true for the Spontaneous process?

1. $∆\mathrm{G}=0$

2. $∆\mathrm{G}>0$

3. $\mathrm{\Delta G}<0$

4. $∆\mathrm{G}=\mathrm{T}∆\mathrm{S}$

Q.

Why is $∆\mathrm{G}$ 0 at equilibrium?

Q. For which of the following reactions, the entropy change will be positive?

1. $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right)$
2. $HCl\left(g\right)+N{H}_3\left(g\right)\rightleftharpoons N{H}_{4}Cl\left(s\right)$
3. $N{H}_{4}N{O}_3\left(s\right)\rightleftharpoons N_{2}O\left(g\right)+2H_{2}O\left(g\right)$
4. $MgO\left(s\right)+H_2\left(g\right)\rightleftharpoons Mg\left(s\right)+H_{2}O\left(l\right)$

Q. Enthalpy change for the process,
$H_{2}O\left(s\right)\rightleftharpoons H_{2}O\left(l\right)$
is $6.01kJmo{l}^{-1}.$ The entropy change for 1 mole of ice at its melting point will be

1. $12J{K}^{-1}mo{l}^{-1}$
2. $22J{K}^{-1}mo{l}^{-1}$
3. $100J{K}^{-1}mo{l}^{-1}$
4. $30J{K}^{-1}mo{l}^{-1}$

Q.

When CuSO4 is added to solution of ammonia then why freezing point is raised

Q. When a solid is converted into liquid, entropy :

1. Becomes zero
2. Remains the same
3. Decreases
4. Increases

Q.

Calculate the entropy change in surroundings when 1.00 mol of $H_2{O}_{\left(l\right)}$ is formed under standard conditions. ${\Delta }_f{H}^{\theta }=-286kJmo{l}^{-1}$.

Q. The entropy change can be calculated by using the expression, $△S=\frac{Q_{rev}}{T}.$ When water freezes in a glass beaker, choose the correct statement amongst the following:

1. $△S_{system}$ decreases but $△S_{surroundings}$ remains the same.
2. $△S_{system}$ increases but $△S_{surroundings}$ decreases.
3. $△S_{system}$ decreases but $△S_{surroundings}$ increases.
4. $△S_{system}$ decreases and $△S_{surroundings}$ also decreases.

Q. In which state, matter has the highest entropy?

1. Solid
2. Liquid
3. Gas
4. Equal in all

Q.

Why is entropy change during reversible adiabatic expansion always zero?

Q. When $2moles$ of an ideal monoatomic gas are heated from $300K$ to $600K$ at constant pressure. The change in entropy of gas $\left(△S\right)$ is:

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

Q. Two blocks of the same metal having same mass and at temperature $T_1$ and $T_2$ respectively, are brought in contact with each other and allowed to attain thermal equilibrium at constant pressure. The change in entropy, $△S$ for this process is

1. $2C_{p}ln\left[\frac{T_1+T_2}{2T_1{T}_2}\right]$
2. $C_{p}ln\left[\frac{(T_1+T_2{)}^2}{4T_1{T}_2}\right]$
3. $2C_{p}ln\left[\frac{(T_1+T_2{)}^2}{4T_1{T}_2}\right]$
4. $2C_{p}ln\left[\frac{(T_1+T_2{)}^{\frac{1}{2}}}{4T_1{T}_2}\right]$

Q.

Why entropy is constant in a reversible adiabatic process.

Q. The standard entropies of $C{O}_2\left(g\right),C\left(s\right)and{O}_2\left(g\right)$ are $213.50,5.74$ and $205J/K$ respectively. The standard entropy of formation of $C{O}_2$ is.

1. $-2.76J/K$
2. $5.76J/K$
3. $2.76J/K$
4. $-5.76J/K$

Q. $\Delta S$ will be the highest for which of the following reactions?

1. $Ca\left(s\right)+\frac{1}{2}{O}_2\to CaO\left(s\right)$
2. $CaC{O}_3\left(s\right)\to CaO\left(s\right)+C{O}_2\left(g\right)$
3. $N_2\left(g\right)+O_2\left(g\right)\to 2NO\left(g\right)$
4. All have same entropy

Q.

The entropy change can be calculated by using the expression $\Delta S=\frac{q_{rev}}{T}$.
When water freezes in a glass beaker, choose the correct statement amongst the following.
(a)$\Delta$S (system) decreases but $\Delta$ S (surroundings) remains the same
(b) $\Delta$S (system) increases but $\Delta$S (surroundings) decreases
(c) $\Delta$S (system) decreases but $\Delta$S (surroundings) increases
(d) $\Delta$S (system) decreases but $\Delta$S (surroundings) also decreases

Q.

What happens to the entropy of the system when the temperature increases?

Q.

What is entropy in one word?

Q.

Entropy change in a cyclic process is zero.

1. True

2. False

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

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

Q. In which of the following entropy decreases ?

1. Crystallization of sucrose from solution

2. Rusting of iron

3. Melting of ice

4. Vaporization of camphor

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. For which of the following the entropy change is negative?

1. Both a and b
2. None of the above
3. Conversion of graphite to diamond
4. Conversion of ozone to oxygen gas

Q.

What happens to the entropy when the evaporation of water takes place?

Q. One mole of an ideal gas expands isothermally and reversibly at ${25}^{o}C$ from a volume of 10 litres to a volume of 20 litres. What is the change in entropy of the gas?

1. 4.76 J/K
2. 5.76 J/K
3. 6.76 J/K
4. 3.76 J/K

Q.

Why is entropy important?

Q. Calculate the total entropy change for the transition at $368K$ of 1 mol of sulphur from the monoclinic to the rhombic solid state. Given $△H$ = $-401.7Jmo{l}^{-1}$ for the transition. Assume the surrounding to be an ice-water bath at $0^{\circ }C$.

1. $-1.09J{K}^{-1}$
2. $1.47J{K}^{-1}$
3. None of these
4. $0.38J{K}^{-1}$