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In Carnot cycle, an ideal gas is taken through 4 reversible steps as shown in the diagram.

Which of the following statement(s) $i s / a r e$ correct?
(i) ΔU is positive in the $2^{n d}$ step between points 2 and 3.
(ii) ΔU is positive in the $4^{t h}$ step between points 4 and 1.
(iii) ΔU is negative in the $2^{n d}$ step between points 2 and 3.
(iv) Temperature at point 4 is higher than point 2.

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Important Questions on Chemical Thermodynamics and Energetics

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

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

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

Consider the following liquid - vapour equilibrium.

L i q u i d ⇌ V a p o u r

Which of the following relations is correct?

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>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>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

The process with negative entropy change is:

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

What will be the $Δ H °$ and $Δ S °$ values for the given cell having $E°$ at $20 ° C$ and $30 ° C$ to be $0.18 V$ and $0.28 V$ respectively?

The cell: (Pt) $H_{2} / H^{+} / / KCl / {Hg}_{2} {Cl}_{2} / Hg$ (Given: $1 F = 96500$ Coulombs)

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

The entropy change associated with the conversion of

1 k g

of ice at

273 K

to water vapours at

383 K

is:

(Specific heat of water liquid and water vapour are

4.2 k J K^{-}

and

2.0 k J K^{- 1} k g^{- 1}

; heat of liquid fusion and vaporization of water are

334 k J k g^{- 1}

and

2491 k J k g^{- 1}

, respectively). (

l o g

273 = 2.436, \log 373 = 2.572, \log 383 = 2.583

)

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

An engine operating between the boiling and freezing points of water will have

A. Efficiency more than $27 %$ .

B. Efficiency less than the efficiency of a Carnot engine operating between the same two temperatures.

C. Efficiency equal to $27 %$ .

D. Efficiency less than $27 %$ .

Choose the correct answer from the options given below

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

For a sample of perfect gas, when its pressure is changed isothermally from

p_{i}

p_{f}

, the entropy change is given by

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

Standard entropies of

X_{2}, Y_{2}

and

{XY}_{3}

are

60, 40

and

50 J / K / mol

respectively. At what temperature the following reaction will be at equilibrium

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

No process is possible whose sole result is the transfer of heat from a colder object to a hotter object. This is Clausius statement for

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

Given:

(i)

C (graphite) + O_{2} (g) \to {CO}_{2} (g);

{ΔrH}^{Θ} = x kJ {mol}^{- 1}

(ii)

C (graphite) + \frac{1}{2} O_{2} (g) \to CO (g);

{ΔrH}^{Θ} = y kJ {mol}^{- 1}

(iii) CO (g) + \frac{1}{2} O_{2} (g) \to {CO}_{2} (g);

{ΔrH}^{Θ} = z kJ {mol}^{- 1}

Based on the above thermochemical equations, find out which one of the following algebraic relationships is correct?

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

For the following reaction

${Fe}_{2} O_{3 (s)} + 3 {CO}_{(g)} ⟶ 2 {Fe}_{(s)} + 3 {CO}_{2 (g)} ΔH ° = - 29.8 kJ$ and $ΔS ° = 15 {JK}^{- 1}$ . What is the value of ${ΔS}_{(total)}$ at $298 K$ ?

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

The heat of combustion of carbon to

C O_{2}

- 393.5 kJ / mol

. The heat released upon the formation of

35.2 g

C O_{2}

from carbon and oxygen gas is

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>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:

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

The heat of atomization of methane and ethane are

360 kJ {mol}^{- 1}

and

620 kJ {mol}^{- 1}

, respectively. The longest wavelength of light capable of breaking the

C - C

bond is (Avogadro's number

= 6.023 \times 10^{23}, h = 6.62 \times 10^{- 34} J s

)

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

Given:

C (graphite) + O_{2} (g) \to {CO}_{2} (g); Δ_{r} H^{o} = - 393 .5 kJ {mol}^{- 1}

H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (l); Δ_{r} H^{o} = - 285 .8 kJ {mol}^{- 1}

{CO}_{2} (g) + 2 H_{2} O (l) \to {CH}_{4} (g) + 2 O_{2} (g); Δ_{r} H^{o} = + 890 .3 kJ {mol}^{- 1}

Based on the above thermochemical equations, the value of

Δ_{r} H^{o}

298 K

for the reaction

C (graphite) + 2 H_{2} (g) \to {CH}_{4} (g)

will be:

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

For which of the following processes,

∆ S

is negative?

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

"Heat cannot be itself flow from a body at lower temperature to a body at higher temperature". This statement corresponds to

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

State the second law of thermodynamics.

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Second Law of Thermodynamics

Two ideal Carnot engines operate in a cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures,

T_{1}

and

T_{2}

. The temperature of the hot reservoir of the first engine is

T_{1}

and the temperature of the cold reservoir of the second engine is

T_{2}

T

is the temperature of the sink of the first engine which is also the source for the second engine. How is

T

related to

T_{1}

and

T_{2}

, if both the engines perform an equal amount of work?

Important Questions on Chemical Thermodynamics and Energetics

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