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-1>Q 54

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IMPORTANT

Earn 100

A gas expands from $2 L$ to $6 L$ against a constant pressure of $0.5$ atm on absorbing $200 J$ of heat. Calculate the change in internal energy.

Important Questions on Thermodynamics

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 55

A piston freely move in a insulated cylinder from volume

5 lit

to

10 lit

then calculate work done and heat during this expansion.

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IMPORTANT

Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 56

If

1.0 kcal

of heat is added to

1.2 L

of

O_{2}

in a cylinder at a constant pressure of

1

atm, the volume increases to

1.5 L .

Calculate

ΔU

and

ΔH

of the process.

(1 L - atm = 100 J, 1 cal = 4.2 J)

HARD

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 57

10 g

of argon gas is compressed isothermally and reversibly at a temperature of

27 ° C

from

10 L

to

5 L .

Calculate the enthalpy change. Assume ideal behaviour

(ΔH)

for this process

R = 2.0 cal K^{- 1} {mol}^{- 1} . \log_{10} 2 = 0.30

(Atomic mass of

Ar = 40

)

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 58

What is

ΔU

when

2.0

mole of liquid water vapourises at

100 ° C ?

The heat of vapourisation

({ΔH}_{vap .})

of water at

100 ° C

is

40.66 KJ {mol}^{- 1} .

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 59

Warming ammonium chloride with sodium hydroxide in a test tube is an example of:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 60

Out of boiling point

(I)

, entropy

(II), pH (III)

, and

e . m . f .

of a cell

(IV)

, the intensive properties are:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 62

Predict the total number of intensive properties:

(i)

Free energy

(ii)

Critical density

(iii)

Viscosity

(iv)

Specific heat capacity

(v)

molar heat capacity

(vi)

Kinetic energy's

(vii)

Specific gravity

(viii)

Dielectric constant

(ix)

pH

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 63

A gaseous system changes from state $A (P_{1}, V_{1}, T_{1})$ to $B (P_{2}, V_{2}, T_{2}), B$ to $C (P_{3}, V_{3}, T_{3})$ and finally from $C$ to $A .$ The whole process may be called: