One mole of a non-ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K)$\to$(4.0 atm, 5.0 L, 245 K) with a change in internal energy, $∆$U = 30.0 L atm. The change in enthalpy ($∆$H) of the process in L atm is:

(a) 40.0

(b) 42.3

(c) 44.0

(d) not defined, because pressure is not constant

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

In a flask, colourless N2O4(g) is in equilibrium with brown coloured NO2(g). At equilibrium when the flask is heated to 100$°$C, the brown colour deepens and on cooling it becomes coloured. Which statement is incorrect about this observation?

(a) The $∆$H for the reaction N2O4(g)$⇌$ 2NO2(g) is +ve

(b) Paramagnetism increases on cooling

(c) The $∆$H-$∆$U at 100$°$C is equal to 200 cal

(d) Dimerisation is reduced on heating

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

When an ideal gas is compressed adiabatically and reversibly, the final temperature is:

(a) higher than the initial temperature

(b) lower than the initial temperature

(c) the same as the initial temperature

(d) dependent on the rate of compression

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

1 litre-atmosphere is equal to:

(a) 101.3 J                           (b) 24.206 cal

(c) 101.3 x 107 erg               (d) all of these

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

An ideal gas expands at a constant external pressure of 2.0 atmosphere by 20 litre and absorbs 10kJ of heat from surrounding. What is the change in internal energy of the system:-

(1) 4052 J

(2) 5948 J

(3) 14052 J

(4) 9940 J

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

36 ml of pure water takes 100 sec to evaporate from a vessel and heater connected to an electric source which delivers 806 watt. The $∆{\mathrm{H}}_{\mathrm{vaporisation}}$ of H2O is:-

(1) 40.3 kJ.mol

(2) 43.2 kJ/mol

(3) 4.03 kJ/mol

(4) None of these

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

The first law of thermodynamics is only

(1) The law of conservation of energy

(2) The law of conservation of mass

(3) The law of conservation of momentum

(4) Both (1) and (2)

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

A mixture of two moles of carbon monoxide and one mole of oxygen, in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If ΔH is the enthalpy change and ΔE is the change in internal energy, then [KCET 2005]

(1) ΔH > ΔE

(2) ΔH < ΔE

(3) ΔH = ΔE

(4) The relationship depends on the capacity of the vessel

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

If ΔH is the change in enthalpy and ΔE the change in internal energy accompanying a gaseous reaction [KCET 1989; CBSE PMT 1990]

(1) ΔH is always greater than ΔE

(2) ΔH < ΔE only if the number of moles of the products is greater than the number of the reactants

(3) ΔH is always less than ΔE

(4) ΔH < ΔE only if the number of moles of the products is less than the number of moles of the reactants

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level:

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 [CMC Vellore 1991]

(1) $2.303×298×0.082\text{\hspace{0.17em}}\mathrm{log}\text{\hspace{0.17em}}2$

(2) $298×{10}^{7}×8.31×2.303\text{\hspace{0.17em}}\mathrm{log}\text{\hspace{0.17em}}2$

(3) $2.303×298×0.082\text{\hspace{0.17em}}\mathrm{log}\text{\hspace{0.17em}}0.5$

(4) $8.31×{10}^{7}×298-2.303\text{\hspace{0.17em}}\mathrm{log}\text{\hspace{0.17em}}0.5$

Concept Videos :-

#2 | State & Path Functions
#5 | Work
#9 | Work done in Isothermal Reversible Expansion
#10 | Work done in Isothermal Irreversible Expansion
#36 | Solved Problems on Thermodynamics: Set 1
#37 | Solved Problems on Thermodynamics: Set 2

Concept Questions :-

First Law of Thermodynamics
Explanation is a part of a Paid Course. To view Explanation Please buy the course.

Difficulty Level: