According to second law of thermodynamics

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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?

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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?

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

Graphs below show the entropy versus energy $U$ of two systems $1$ and $2$ at constant volume. The initial energies of the systems are indicated by $U_{1, i}$ and $U_{2, i},$ respectively. Graphs are drawn to the same scale. The systems are then brought into thermal contact with each other. Assume that, at all times the combined energy of the two systems remains constant. Choose the most appropriate option indicating the energies of the two systems and the total entropy after they achieve the equilibrium.

Question Image

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

By leaving the door of a small standard domestic refrigerator open, it is not possible to cool a room, because it violates the ______

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

The carnot heat engine have an efficiency of

50 % .

The temperature of sink is maintained at

500 K .

To increase the efficiency upto

80 %,

the increment in the source temperature is

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

One mole of an ideal monatomic gas undergoes the following four reversible processes:
Step

1 :

It is first compressed adiabatically from volume

V_{1}

to

1 m^{2} .

Step

2 :

then expanded isothermally to volume

10 m^{3}

Step

3 :

then expanded adiabatically to volume

V_{3}

Step

4 :

then compressed isothermally to volume

V_{1} .

If the efficiency of the above cycle is

\frac{3}{4}

then

V_{1}

is

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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:

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

Two solid blocks at temperatures

T_{1}

and

T_{2} (T_{1} < T_{2})

are put in thermal contact for a long time inside an insulated container. Choose the correct statement(s).

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

State the second law of thermodynamics.

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

One mole of an ideal gas at

300 K

in thermal contact with its surroundings expands isothermally from

1.0 L

to

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})

in

J K^{- 1}

is:

(1 L atm = 101.3 J)

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

Consider a two stage Carnot engine. In the first stage heat

Q_{1}

is absorbed at temperature

T

and heat

Q_{2}

is expelled at temperature

α T

(where

α < 1

). In the second stage heat

Q_{2}

is absorbed at temperature

α T

and heat

Q_{3}

is expelled at temperature

β T (β < α) .

The efficiency of the Carnot engine will be

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

The process with negative entropy change is:

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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

)

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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)

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Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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 $298 K$ ?

According to second law of thermodynamics :

Important Questions on Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.

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