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.

E M B I B E

Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 90

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A certain mass of gas is expanded from $(1 L, 10 atm)$ . to $(4 L, 5 atm)$ against a constant external pressure of $1$ $atm$ . If initial. The temperature of the gas is $300 K$ and the heat capacity of the process is $50 J / {}^{\circ}C$ . Then the enthalpy change during the process is $(1 L$ $≃ 100 J)$ .

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Important Questions on Thermodynamics

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 91

2

moles of an ideal gas is expanded isothermally & reversibly from

1

litre to

10

litre. Find the enthalpy change in

kJ {mol}^{- 1}

.

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 92

One mole of an ideal monoatomic gas at temperature $T$ and volume $1 L$ expands $2 L$ against a constant external pressure of one $atm$ under adiabatic conditions, then the final temperature of the gas will be:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 93

The ratio of P to V at any instant is constant and is equal to 1 for a monoatomic ideal gas undergoing a process. What is the molar heat capacity of the gas?

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 94

An ideal gas expands in volume from