The following reaction is performed at 298 K . 2 N O g + O 2 g ⇌ 2 N O 2 g The standard free energy of the formation of N O g is 86 . 6 kJ mol - 1 at 298 K . What is the standard free energy of the formation of N O 2 g at 298 K ? ( K P = 1.6 × 10 12 )

0.5 [ 2 × 86,600 - R 298 ln ⁡ ( 1.6 × 10 12 ) ]

R 298 ln ⁡ 1.6 × 10 12 -86,600

86,600 + R 298 ln ⁡ ( 1.6 × 10 12 )

86,600 - ln ⁡ ( 1.6 × 10 12 ) R ( 298 )

For the process H 2 O l → H 2 O g at T = 100 o C and 1 atmosphere pressure, the correct choice is-

∆ S s y s t e m > 0 a n d ∆ S s u r r o u n d i n g < 0

∆ S s y s t e m > 0 a n d ∆ S s u r r o u n d i n g > 0

∆ S s y s t e m < 0 a n d ∆ S s u r r o u n d i n g > 0

∆ S s y s t e m < 0 ∆ S s u r r o u n d i n g < 0

EASY

Earn 100

In which of the following processes, entropy of the system increases?

$I$ ) Temperature of a crystalline solid is raised from $0 K$ to $115 K$ .

$II$ ) Liquid crystallizing to solid.

$III$ ) $2 {NaHCO}_{3} (s) ⟶ {Na}_{2} {CO}_{3} (s) + {CO}_{2} (g) + H_{2} O (g)$

$IV$ ) Vaporization of a liquid.

50% studentsanswered this correctly

Important Questions on Thermodynamics

HARD

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

The following reaction is performed at

298 K

2 N O (g) + O_{2} (g) ⇌ 2 N O_{2} (g)

The standard free energy of the formation of

N O (g)

86.6 kJ {mol}^{- 1}

298 K

. What is the standard free energy of the formation of

N O_{2} (g)

298 K

(K_{P} = 1.6 \times 10^{12})

HARD

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

One mole of an ideal gas at

300 K

in thermal contact with its surroundings expands isothermally from

1.0 L

2.0 L

against a constant pressure of

3.0 atm

. In this process, the change in entropy of the surroundings

(∆ S_{s u r r})

J K^{- 1}

is:

(1 L atm = 101.3 J)

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

For the process

H_{2} O (l) \to H_{2} O (g)

T = 100^{o} C

and

1

atmosphere pressure, the correct choice is-

EASY

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

In which case change in entropy is negative?

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

A process has

Δ H = 200 J m o l^{- 1}

and

Δ S = 40 J K^{- 1} m o l^{- 1} .

Out of the values given below choose the minimum temperature above which the process will be spontaneous:

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

For the reaction;

A (l) \to 2 B (g)

Δ U = 2.1 k c a l, Δ S = 20 c a l K^{- 1}

300 K .

Hence

Δ G

k c a l

is _____________.

EASY

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following:

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

Using the Gibbs change,

∆ G^{o} = + 63.3 k J,

for the following reaction,

A g_{2} C O_{3} (g) ⇌ 2 A g^{+} (a q) + C O_{3}^{2 -} (a q)

the

K_{s p}

A g_{2} C O_{3} (s)

in water at

25^{o} C

(R = 8.314 J K^{- 1} m o l^{- 1})

EASY

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is:

EASY

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

For a given reaction,

Δ H = 35.5 k J m o l^{- 1}

and

Δ S = 83.6 J K^{- 1} m o l^{- 1} .

The reaction is spontaneous at : (Assume that

Δ H

and

Δ S

do not vary with temperature)

HARD

Chemistry>Physical Chemistry>Thermodynamics>Entropy and Second Law of Thermodynamics

The surface of copper gets tarnished by the formation of copper oxide. $N_{2}$ gas was passed to prevent the oxide formation during heating of copper at 1250 K. However, the $N_{2}$ gas contains 1 mole % of water vapour as impurity. The water vapour oxidises copper as per the reaction given below:

$2 Cu (s) + H_{2} O (g) \to {Cu}_{2} O (s) + H_{2} (g)$

$P_{H_{2}}$ Is the minimum partial pressure of $H_{2}$ (in bar) needed to prevent the oxidation at $1250 K$ . The magnitude of value of $\ln (P_{H_{2}})$ is ____.

(Given: total pressure = 1 bar, R (universal gas constant) $= 8 J K^{- 1} {mol}^{- 1}, \ln (10) = 2 .3 . Cu (s) and {Cu}_{2} O (s)$ are mutually immiscible.

At $1250 K : 2 Cu (s) + \frac{1}{2} O_{2} (g) \to {Cu}_{2} O (s); ∆ G^{⊝} = - 78,000 J {mol}^{- 1}$

$H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (g); ∆ G^{⊝} = - 1,78,000 J {mol}^{- 1};$ )