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Entropy

Entropy

Trending Questions

Q. For the process,

H_{2} O (l) \to H_{2} O (g) a t T = 100^{\circ} C

and 1 atmosphere pressure, the correct choice

$Δ S_{s y s t e m} > 0 a n d Δ S_{s u r r o u n d i n g} > 0$
$Δ S_{s y s t e m} > 0 a n d Δ S_{s u r r o u n d i n g} < 0$
$Δ S_{s y s t e m} < 0 a n d Δ S_{s u r r o u n d i n g} > 0$
$Δ S_{s y s t e m} < 0 a n d Δ S_{s u r r o u n d i n g} < 0$

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Q.

The degree of randomness or disorder in a system is known as entropy

True
False

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Q. 3.The temperature entropy diagram of a reversible engine cycle is given in the figure.Its efficiency is a)1/2 b)1/4 c)1/3 d)2/3

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Q. Find out the value of equilibrium constant for the following reaction at 298 K.

2 N H_{3 (g)} + C O_{2 (g)} ⇌ N H_{2} C O N H_{2 (a q)} + H_{2} O_{(l)}

Standard Gibbs energy change

Δ_{r} G^{\circ}

at the given temperature is

- 13.6 K J m o l^{- 1}

24
12
240
2400

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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?

4.76 J/K
5.76 J/K
3.76 J/K
6.76 J/K

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Q.

If total enthalpy of reactants & products is $H_{R}$ & $H_{P}$ respectively, then for exothermic reaction:

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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

$2 C_{p} l n [\frac{T_{1} + T_{2}}{2 T_{1} T_{2}}]$
$C_{p} l n [\frac{(T_{1} + T_{2})^{2}}{4 T_{1} T_{2}}]$
$2 C_{p} l n [\frac{(T_{1} + T_{2})^{2}}{4 T_{1} T_{2}}]$
$2 C_{p} l n ⎡ ⎢ ⎢ ⎢ ⎢ ⎣ \frac{(T_{1} + T_{2})^{\frac{1}{2}}}{4 T_{1} T_{2}} ⎤ ⎥ ⎥ ⎥ ⎥ ⎦$

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Q.

Entropy is a state function.

True
False

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Q.

The degree of randomness or disorder in a system is known as entropy

True
False

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Q.

2 moles of an Ideal Gas are compressed isothermally ( $100^{\circ} C$ ) and reversibly from a pressure of 10 atm to 25 atm. The value of Wrev is

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Q. Why is the Entropy of Adsorption of H2 on glass surface positive?

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Q.

Calculate the change in entropy for the following reaction
$2 C O (g) + O_{2} (g) \to 2 C O_{2} (g)$ .
Given $S_{C O_{2}}^{0} = 213.6 J K^{- 1} m o l^{- 1}$ , $S_{C O}^{0} = 297.6 J K^{- 1} m o l^{- 1}$ respectively.

None of these
-185.03 $J K^{- 1} m o l^{- 1}$
-143.03 $J K^{- 1} m o l^{- 1}$
-173.03 $J K^{- 1} m o l^{- 1}$

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

Becomes zero
Remains the same
Decreases
Increases

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Q. 33. Give all different numerical value of gas constant R

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Q. Which of the following reaction(s) has a positive entropy change?

(I) A g^{+} (a q) + C l^{-} (a q) \to A g C l (s) (I I) N H_{4} C l (s) \to N H_{3} (g) + H C l (g) (I I I) 2 N H_{3} (g) \to N_{2} (g) + 3 H_{2} (g)

I and II
III
II and III
II

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Q. For a liquid, enthalpy of fusion is

1.435 k c a l m o l^{- 1}

and molar entropy change is

5.26 c a l m o l^{- 1} K^{- 1}

The melting point of the liquid is:

$100^{\circ} C$
$0^{\circ} C$
$273^{\circ} C$
$373^{\circ} C$

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Q. what is the meaning of "overall entropy change of universe associated with spontaneous process is positive"?

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Q. In which case is the change in entropy negative?

Evaporation of water
Expansion of a gas at constant temperature
Sublimation of solid to gas
$2 H (g)$ $⟶$ $H_{2} (g)$

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Q. Calculate the entropy change (in

J K^{- 1} m o l^{- 1}

) for vaporisation of liquid water to steam at

100^{\circ} C

. Given that heat of vaporisation is

40.8 k J m o l^{- 1}

.

109.38
100.38
120.38
129.38

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Q. What is the unit for entropy change?

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Q. For a perfectly crystalline solid

C_{p . m} = a T^{3} + b T

, where a and b are constants. If

C_{p . m}

is

0.40 J/Kmol

at 10 K and

0.92 J/K mol

at 20K, then the molar entropy at 20 K is:

$0.920 J/K mol$
$8.66 J/K mol$
$0.813 J/K mol$
None of these

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Q. For a reaction:

X \to Y + Z

The absolute entropies for

X, Y

and

Z

are

120 J K^{- 1} m o l^{- 1}, 213.8 J K^{- 1} m o l^{- 1} a n d 197.9 J K^{- 1} m o l^{- 1}

respectively.
What will be the entropy change of the reaction at 298 K and 1 atm?

$291.7 J K^{- 1}$
$255 J K^{- 1}$
$213.8 J K^{- 1}$
$257.3 J K^{- 1}$

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Q.

Calculate the change in entropy for the following reaction
$2 C O (g) + O_{2} (g) \to 2 C O_{2} (g)$ .
Given $S_{C O_{2}}^{0} = 213.6 J K^{- 1} m o l^{- 1}$ , $S_{C O}^{0} = 297.6 J K^{- 1} m o l^{- 1}$ respectively.

-185.03 $J K^{- 1} m o l^{- 1}$
-143.03 $J K^{- 1} m o l^{- 1}$
-173.03 $J K^{- 1} m o l^{- 1}$
None of these

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Q. What happens when gas in a closed vessel is heated :

An increase in entropy
A decrease in entropy
An increase in heat of vaporization
An increase in free energy

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Q. An adiabatic process is one in which there is no transfer of heat across the boundary between system and surroundings. For such a process.

$q = w$
$P_{e x t} Δ V = 0$
$Δ U = w$
$Δ U = 0$

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Q. One mole of an ideal gas at

300 K

in thermal contact with surrounding expands isothermally from

1.0 L t o 2.0 L

against a constant pressure of

3.0 a t m .

In this process, the change in entropy of surroundings

(Δ S_{surr})

in

J K^{- 1}

is:

(G i v e n : 1 L a t m = 101.3 J)

5.763
1.013
-1.013
-5.763

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Q.

Entropy change in a cyclic process is zero.

True
False

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Q. Enthalpy change for the process,

H_{2} O (s) ⇌ H_{2} O (l)

is

6.01 k J m o l^{- 1} .

The entropy change for 1 mole of ice at its melting point will be

$12 J K^{- 1} m o l^{- 1}$
$22 J K^{- 1} m o l^{- 1}$
$100 J K^{- 1} m o l^{- 1}$
$30 J K^{- 1} m o l^{- 1}$

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Q. Calculate the critical constants of a gas whose van der Waals constants A and b are 0.751L²atm mol^-2 and 0.0225Lmol^-1

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Q. The enthalpy of vaporisation of liquid diethyl ether is

26.0 k J m o l^{- 1}

at its boiling point

{35.0}^{o} C .

Calculate

△ S

for conversion of vapour to liquid at

{35.0}^{o} C

in

J K^{- 1} m o l^{- 1}

.

$- 84.41$
$+ 84.41$
$- 48.41$
$+ 48.41$

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