The enthalpy of combustion of propane C 3 H 8 gas in terms of given data is : Bond energy kJ mol - 1 ε C - H ε O = O ε C = O ε O - H ε C - C + x 1 + x 2 + x 3 + x 4 + x 5 Resonance energy of CO 2 is - z kJ mol - 1 and ΔH vaporization H 2 O ℓ is y kJ mol - 1 .

8 x 1 + 2 x 5 + 5 x 2 - 6 x 3 - 8 x 4 - 4 y - 3 z

6 x 1 + x 5 + 5 x 2 - 3 x 3 - 4 x 4 - 4 y - 3 z

8 x 1 + 2 x 5 + 5 x 2 - 6 x 3 - 8 x 4 - y - z

8 x 1 + x 5 + 5 x 2 - 6 x 3 - 8 x 4 - 4 y + 3 z

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.

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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Which of the following is not a state function?

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Important Questions on Thermodynamics

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 9

The work done (in erg) for the reversible expansion of one mole of an ideal gas from a volume of

10

Litres to

20

Litres at

25 ° C

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 10

A coffee cup calorimeter initially contains $125 g$ of water, at a temperature of $24.2 ° C$ . $8 g$ of ammonium nitrate (NH₄NO₃), also at $24.2 ° C$ , is added to the water, and the final temperature is $18.2 ° C$ . What is the heat of solution of ammonium nitrate in kJ/mol? The specific heat capacity of the solution is $4.2 J / g ° C$ .

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 11

The molar heat capacities at constant pressure (assumed constant with respect to temperature) at

A, B

and

C

are in ratio of

3 : 1.5 : 2.0

. The enthalpy change for the exothermic reaction

A + 2 B ⟶ 3 C

300 K

and

310 K

{ΔH}_{300}

{ΔH}_{310}

respectively then:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 12

Heat of combustion of ethanol at constant pressure and at temperature

T K

is found to be

- q {Jmol}^{- 1} .

Hence, heat of combustion

(in {Jmol}^{- 1})

of ethanol at the same temperature at constant volume will be:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 13

When 1.0 g of oxalic acid (H₂C₂O₄) is burned in a bomb calorimeter whose heat capacity is 8.75 kJ/K, the temperature increases by 0.312 K. The enthalpy of combustion of oxalic acid at 27^oC is :

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 19

When $0.1$ mole of ice melts at $0 ° C$ at constant pressure of $1$ atm, $144$ calories of heat are absorbed by the system. Calculate the $ΔH$ for the reaction.

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 20

One mole of ideal monoatomic gas is carried through the reversible cyclic process as shown in figure. Calculate the net heat absorbed by the gas in the path BC.

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-4>Q 22

The enthalpy of combustion of propane $(C_{3} H_{8})$ gas in terms of given data is :

Bond energy $(kJ {mol}^{- 1})$

$ε_{C - H}$	$ε_{O = O}$	$ε_{C = O}$	$ε_{O - H}$	$ε_{C - C}$
$+ x_{1}$	$+ x_{2}$	$+ x_{3}$	$+ x_{4}$	$+ x_{5}$

Resonance energy of ${CO}_{2}$ is $- z kJ {mol}^{- 1}$ and ${ΔH}_{vaporization} [H_{2} O (ℓ)]$ is $y kJ {mol}^{- 1}$ .

Which of the following is not a state function?

Important Questions on Thermodynamics

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