Applications of First Law of Thermodynamics

IMPORTANT

Applications of First Law of Thermodynamics: Overview

This topic covers concepts, such as, Work Done in Reversible Adiabatic Process, Work Done in An Isothermal Expansion For Ideal System, Interpretation of Work from Graph of Cyclic Processes & Reversible Polytropic Process etc.

Important Questions on Applications of First Law of Thermodynamics

MEDIUM
IMPORTANT

The work done during the expansion of a gas from a volume of 4dm3to6dm3against a constant external pressure of 3 atm is (1 L atm = 101.32 J):

                               

MEDIUM
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In a container 3.2 g of oxygen gas is kept at 20 atm and 300K. The gas is allowed to expand isothermally against constant external pressure of 1 atm till the final pressure reaches to 1 atm. Calculate the magnitude of work done by the gas.(The nearest integer)

MEDIUM
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0.1 moles of a diatomic gas at 27°C is heated at constant pressure, so that the volume is doubled. If R=2 cal/mol, the work done by gas in cal will be

MEDIUM
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3 moles of an ideal gas expands isothermally against a constant pressure of 2 Pascal from 20 L to 60 L.The amount of work involved is

MEDIUM
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5 moles of an ideal monoatomic gas undergoes adiabatic expansion from 5 L to 20 L against a constant external pressure of 2 bar.

MEDIUM
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One mole of an ideal gas is taken from a and b along two paths denoted by the solid and the dashed lines as shown in the graph below. If the work done along the solid line path is ws and that along the dotted line path is wd, then the integer closest to the ratio wd/ws is:

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MEDIUM
IMPORTANT

Two moles of He gas (γ=5/3) are initially at temp 27°C and occupy a volume of 20 litres. The gas is first expanded at constant pressure until its volume is doubled. Then it undergoes reversible adiabatic change, until the volume become 110 lit, then predict the value of T/100 (where T is the final temperature, 4112/3=12)

MEDIUM
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Select the incorrect statement about the above diagram.

MEDIUM
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An ideal gas undergoes adiabatic expansion against constant external pressure. Which of the following is incorrect:

HARD
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Calculate  ΔGin kJ (in magnitude) for the process, one mole of an ideal gas at 22.4 litres is expanded isothermally and reversibly at 300 K to a volume of 224 litres.

Give your answer as the nearest integer.

MEDIUM
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In the given graph, the area of circle A and B are 40 unit and 36 unit respectively, total work done ' x ' unit.

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When a system is taken from stateA to B along path A C B, as shown in the figure, 3 unit of heat flows into the system and the system does 3 unit of work. If ' y ' unit heat flows into the system along the path ADB, and the work done by the system is 2 unit?
Then the value of x+y is

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EASY
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The enthalpy change of a reaction is independent of

HARD
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q, w, ΔE and ΔH for the following process ABCD for a monoatomic gas are:

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HARD
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Consider the reversible isothermal expansion of an ideal gas in a closed system at two different temperatures T1 and T2 T1<T2. The correct graphical depiction of the dependence of work done w on the final volume v.

MEDIUM
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A thermodynamic cycle in the pressure P-volume V plane is given below:
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AB and CD are isothermal processes while BC and DA are adiabatic processes. The same cycle in the temperature T- entropy S plane is :

HARD
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During the free expansion of an ideal gas in an isolated chamber,
 

MEDIUM
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A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 ml to 375 ml at a constant temperature of 37.0°C. As it does so, it absorbs 208 J of heat. The values of q and w for the process will be

(R=8.314 J/mol K) (ln7.5=2.01)

MEDIUM
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One mole of an ideal gas (at 25°C ) is expanded from volume 1 L to 4 L at constant temperature. The value of work done (in J), if gas is expanded against vacuum Pext=0?

HARD
IMPORTANT

For next two question please follow the same

Work done by the system in isothermal reversible process is: wrev= -2.303 nRTlogV2V1 . Also in case of adiabatic reversible process work done by the system is given by: wrev=nRγ-1[T2-T1] . During expansion disorder increases and the increase in disorder is expressed in terms of change in entropy ΔS=ΔHT . Both entropy and enthalpy changes obtained for a process were taken as a measure of spontaneity of process but finally it was recommended that decrease in free energy is responsible for spontaneity and ΔH-TΔS.

Which of the following statements are correct:

(1) The expansion work for a gas into vacuum is equal to zero.

(2) 1 mole of a gas occupying 3 litre volume on expanding to 15 litre at constant pressure of 1 atm does expansion work 1.215 kJ.

(3) The maximum work done during expansion of 16 g O2 at 300 K from 5 dm3 to 25 dm3 is -2.01 KJ.

(4) The ΔS for  S L is almost negligible in comparison to ΔS for L G .

(5) ΔS=2.303 nRlogV2V1 (At constant T)

HARD
IMPORTANT

For next two question please follow the same

A sample of an ideal gas is expanded to twice its original volume of 1 m3 in a reversible process for which  α = 5 atm  m - 6   and  C Vm = 20 J K -1 m -1 at constant volume.

The work done during the process may be