Nature of heat and work

IMPORTANT

Nature of heat and work: Overview

This topic covers concepts such as free expansion, work, mechanical work, sign conventions for work and mathematical expression for irreversible work.

Important Questions on Nature of heat and work

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Which of the following is the SI unit of work?

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Mechanical work is a _____ quantity.

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Define mechanical work and give the formula to calculate work. Is work a vector or scalar quantity?

EASY
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Define path function.

HARD
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The conditions for a system to be able to completely obtain all the work possible is

EASY
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Which process has maximum work done?

EASY
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1 calorie = _____ joule.(write answer up to 2 decimal)

HARD
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If the work is done by the system,wad will be negative because _____ .

HARD
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According to IUPAC conventions work done on the surroundings is :

HARD
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Which of the following statements are correct as per IUPAC sign convention ?

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For next two question please follow the same

The pressure-volume graphs of various thermodynamics processes are shown:

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Work is the mode of transference of energy. It has been observed that reversible work done by the system is maximum obtainable work.

wrev > wirr

The works of isothermal and adiabatic processes are different from each other.

- w isothermal reversible = 2.303 nRT log 1 0 V 2 V 1

= 2.303 nRT log 1 0 P 1 P 2

- w adiabatic reversible = C V T 1 - T 2

If w1, w2, w3 and w4 are magnitude of work done in isothermal, adiabatic, isobaric and isochoric reversible processes, respectively, then the correct sequence (for expansion) would be

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The work done during the expansion of a gas from 4 dm3 to 6 dm3 against a constant external pressure of 3 atm is (1 L atm=101.32 J)

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Calculate the work done in each of the following reactions. State whether work is done on or by the system.

Decomposition of 2 moles of NH4NO3 at 100°C

NH4NO3 (s)  N2O (g) + 2H3O (g)

HARD
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Calculate the work done in each of the following reactions. State whether work is done on or by the system.

The oxidation of one mole of SO2 at 50°C.

2SO2 (g) + O2 (g)  2SO3 (g)

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2.8  x 10-2 Kg of nitrogen is expanded isothermally and reversibly at 300K from 15.15 x 105 Nm-2 when the work done is found to be -17.33 kJ. Find the final pressure.

HARD
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Three moles of an ideal gas are compressed isothermally and reversibly to a volume of 2 L. The work done is 2.983 kJ at 22°C. Calculate the initial volume of the gas.

HARD
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Calculate the maximum work when 24 g of oxygen are expanded isothermally and reversibly from a pressure of 1.6×105 Pa to 100 kPa at 298 K.

HARD
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One mole of an ideal gas is compressed from 500 cm3 against a constant pressure of 1.216×105 Pa. The work involved in the process is 36.50 J. Calculate the final volume.

HARD
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Three moles of an ideal gas are expanded isothermally from a volume of 300 cm3 to 2.5 L at 300 K against a pressure of 1.9 atm. Calculate the work done in L atm and joules.

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In what reaction of the following, work is done by the system on the surroundings?