State the second law of thermodynamics.

The second law of thermodynamics can be expressed in terms of entropy. It can be stated as “the entropy of an isolated system increases during a spontaneous process”. The total entropy change ( ∆ S total ) for the system and the surroundings of a spontaneous process is given by, ∆ S total = ∆ S system + ∆ S surrounding > 0 When a system is in equilibrium, the entropy is maximum and the change in entropy, ∆ S = 0 . Hence, entropy of a spontaneous process increases till it reaches a maximum and at equilibrium the change in entropy is zero.

The work done in ergs for the reversible expansion of one mole of an ideal gas from a volume of 10 litres to 20 litres at 25 ° C is

298 × 10 7 × 8 . 31 × 2 . 303 log 2 .

2 . 303 × 298 × 0 . 082 log 2 .

2 . 303 × 298 × 0 . 082 log 0 . 5 .

8 . 31 × 10 7 × 298 × 2 . 303 log 0 . 5 .

For a reaction taking place in a container in equilibrium with its surroundings, the effect of temperature on its equilibrium constant K in terms of change in entropy is described by:

with increase in temperature, the value of K for exothermic reaction decreases because favourable change in entropy of the surroundings decreases.

with increase in temperature, the value of K for exothermic reaction decreases because the entropy change of the system is positive.

with increase in temperature, the value of K for endothermic reaction increases because the entropy change of the system is negative.

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A system containing real gas changes its state form state $1$ to state $2$ .

State $1$ $(2 atm, 3 L, 300 K)$
State $2$ $(5 atm, 4 L, 500 K)$
If the change in internal energy is $30 L . atm$ , calculate the change in enthalpy?

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Important Questions on Thermodynamics

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 37

Which one of the following statements is false?

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 38

Identify the state function among the following:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 39

Two moles of helium gas undergo a reversible cyclic process as shown in the figure. Assuming the gas to be ideal, what is the net work involved in the cyclic process?

Question Image

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 40

Ice-Water mass ratio is maintained as

1 : 1

in a given system containing water in equilibrium with ice at constant pressure. If

C_{P} (ice) = C_{P} (water) = 4.18 {Jmol}^{- 1} K^{- 1}

, What is the molar heat capacity of such a system?

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 41

Two moles of an ideal gas are heated at a constant pressure of one atmosphere from

27 ° C

127 ° C

. If

C_{v, m} = 20 + 10^{- 2} {TJK}^{- 1} {mol}^{- 1},

q

and

Δ U

for the process are, respectively:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 43

Consider a classroom that is roughly

5 m \times 10 m \times 3 m .

Initially,

t = 27 ° C

P = 1

atm. There are

50

people in an insulated class losing energy to the room at the average rate of

150

Watt per person. How long can they remain in the class if the body temperature is

42 ° C

and the person feels uncomfortable above this temperature? Heat capacity of air

= (7 / 2) R

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 45

There are two samples of the same gas, initially under the similar initial state. Gases of both the samples are expanded.

I^{st}

sample using reversible isothermal process and

{II}^{nd}

sample using reversible adiabatic process till the final pressures of both the samples becomes half of the initial pressure. Then:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-5>Q 47

In a laboratory, liquid in a thermally insulated container is stirred for one hr, by a mechanical linkage to an in the surrounding, for this process:

A system containing real gas changes its state form state 1 to state 2. State 1 (2atm, 3L, 300K) State 2 (5atm, 4L, 500K) If the change in internal energy is 30 L.atm, calculate the change in enthalpy?

Important Questions on Thermodynamics

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A system containing real gas changes its state form state $1$ to state $2$ .

State $1$ $(2 atm, 3 L, 300 K)$
State $2$ $(5 atm, 4 L, 500 K)$
If the change in internal energy is $30 L . atm$ , calculate the change in enthalpy?