EASY

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For an ideal gas, the relation between the enthalpy change and internal energy at constant temperature is given by

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Important Questions on Thermodynamics

HARD

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

What will be the enthalpy of reaction

2 NO + O_{2} \to 2 {NO}_{2}

from the given formation enthalpy values ? The standard enthalpy of formation values for

O_{2},

NO

and

{NO}_{2}

are as follows:

O_{2} (g) : 0 kJ / mol, NO (g) : 90.25 kJ / mol

and

{NO}_{2} (g)

33.18 kJ / mol

respectively.

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Calculate the work done during the reactions represented by the following thermochemical equation at

300 K

\underset{(g)}{{CH}_{4}} + \underset{(g)}{2 O_{2}} \to \underset{(g)}{{CO}_{2}} + \underset{(l)}{2 H_{2} O}

(R = 8.314 {JK}^{- 1} {mol}^{- 1})

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Which of the following relation is not correct?

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

The standard enthalpy of vaporisation

Δ_{vap} H °

, for water at

100 ° C

40.66 kJ {mol}^{- 1}

. The internal energy of vaporisation of water at

100 ° C

(in

{kJmol}^{- 1}

) is (assume water vapour to behave like an ideal gas)

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

For which of the following systems, the difference between $ΔH$ and $ΔU$ is not significant?

(i) Solids

(ii) Gases

(iii) Mixture of gases and liquids

(iv) Liquids

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Consider the following reaction:

CaO (s) + {CO}_{2} (g) ⟶ {CaCO}_{3} (s)

. The reaction is spontaneous at low temperature because

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

$A$ fish swimming in water body when taken out from the water body is covered with a film of water of weight $36 g$ . When it is subjected to cooking at $100 ° C$ , then the internal energy for vaporization in ${kJmol}^{- 1}$ is integer]

[Assume steam to be an ideal gas. Given $Δ_{vap} H^{⊖}$ for water at $373 K$ and $1$ bar is $41.1 kJ {mol}^{- 1} : R = 8.31 J K^{- 1} {mol}^{- 1}$ ]

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

At constant volume,

4 m o l

of an ideal gas when heated from

300 K

500 K

changes its internal energy by

5000 J .

The molar heat capacity at constant volume is ________

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

2

moles of a monoatomic ideal gas at

25^{o} C

is heated reversibly at a constant pressure of

2 atm

to reach a final temperature of

125^{o} C

. Calculate the

Δ H . (C_{v} = \frac{3}{2} R)

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

A better criterion for ideality of a gas than

{(\frac{\partial U}{\partial V})}_{T} = 0

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Which of the following process best describes atomization of

C H_{4} (g) ?

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Two moles on an ideal gas is expanded isothermally and reversibly at 300 K form 1 L to 10 L. The enthalpy change in KJ is

HARD

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Calculate the work done in the following reaction at $50 ° C$ . State whether work is done on the system or by the system.

${SO}_{2 (g)} + \frac{1}{2} O_{2 (g)} \to {SO}_{3 (g)}$

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Find the approximate value of

(ΔH - ΔU)

J \cdot {mol}^{- 1}

, for the formation of

CO

from its elements at

298 K

(R = 8.314 J \cdot K^{- 1} {mol}^{- 1})

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

X g

of ice at

0^{o} C

is added to 340g of water at

20^{o} C

. The final temperature of the resultant mixture is

5^{o} C

. The value of

X

(in g) is closest to

[Heat of fusion of ice

= 333 J / g

; Specific heat of water

= 4.184 J / g . K

]

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

At constant pressure, the heat of formation of a compound is not dependent on temperature, when

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Two moles of helium gas is mixed with three moles of hydrogen molecules (taken to be rigid). What is the molar specific heat of mixture at constant volume?

(R = 8.3 J / m o l K)

EASY

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

For the formation of

{NH}_{3} (g)

from its constituent elements at constant temperature and presssure, which of the following options is correct

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

The internal energy change (in $J$ ) when $90 g$ of water undergoes complete evaporation at $100 ° C$ is ..............

(Given : ${ΔH}_{vap}$ for water at $373 K = 41 kJ / mol$ , $R = 8.314 {JK}^{- 1} {mol}^{- 1}$ )

MEDIUM

Chemistry>Physical Chemistry>Thermodynamics>Applications of Thermodynamics: Enthalpy

Identify the equation in which change in enthalpy is equal to change in internal energy

For an ideal gas, the relation between the enthalpy change and internal energy at constant temperature is given by

Important Questions on Thermodynamics

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