First Law of Thermodynamics

IMPORTANT

First Law of Thermodynamics: Overview

This Topic covers sub-topics such as First Law of Thermodynamics, Polytropic Process, Adiabatic Process Examples, First Law of Thermodynamics in Isothermal Process, Heat in Isothermal Process and, First Law of Thermodynamics in Adiabatic Process

Important Questions on First Law of Thermodynamics

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An ideal gas is allowed to expand freely against vacuum in a rigid insulated container. The gas undergoes

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If an ideal diatomic gas follows the process as shown in graph, where T is temperature in kelvin and V is volume in m3, then molar heat capacity for this process will be [in terms of gas constant R],

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A cycle tyre bursts suddenly. What is the type of this process?

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A monatomic ideal gas undergoes a process ABC. The heat given to the gas is,

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P-V plots for two gases during adiabatic processes are shown in the figure. Plots 1 and 2 should correspond respectively to:

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In adjoining diagram, no heat exchange between the gas and the surroundings will take place if the gas is taken along:

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One mole of an ideal monatomic gas is taken through a semicircular thermodynamic process ACB shown in the PV diagram. The heat supplied to the system is

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One mole of a mono-atomic gas undergoes the processes 1-2 and 2-3 as shown. The corresponding graph for the above process for 2 moles of the gas is

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A given mass of gas at a pressure P and absolute temperature T obeys the law PT3 during an adiabatic process. The adiabatic bulk modulus of the gas at a pressure P is

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The workdone on the system in changing the state of a gas adiabatically from equilibrium state A to equilibrium state B is 32.4 J. If the gas is taken from state A to B through another process in which the net heat absorbed by the system is 13.5 cal, then the net workdone by the system in the later case is 1 cal=4.2 J

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An electric heater supplies heat to a system at a rate of 100 W. If the system performs Work at a rate of 60 joules per second, the rate at which internal energy changes is

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Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains an ideal gas at standard temperature T1 and pressure. B is empty. Then the entire system is thermally insulated. The stopcock is suddenly opened. After the gas reaches equilibrium the temperature T2 of the gas measured. Which of the following is correct?

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1 gm of water at 100 °C, is completely converted to steam at 100 °C, occupies 1800 cc. The increase in the internal energy of the molecules is:
(take the pressure =105 Pa, Latent heat of vaporisation L=540 cal gm-1,1cal=4.2 J)

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An ideal monatomic gas with pressure P, volume V and temperature T is expanded isothermally to a volume 2V and a final pressure Pi. If the same gas is expanded adiabatically to a volume 2V, the final pressure is Pa. The ratio PaPi is
 

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As shown in the figure, the amount of heat absorbed along the path ABC is 90 J and the amount of work done by the system is 30 J. If the amount of work done along the path ADC is 20 J the amount of heat absorbed will be:

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For an adiabatic expansion of ideal gas, the value of Δpp is equal to

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One mole of an ideal monoatomic gas is taken round the cyclic process ABCA as shown in figure then

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One mole of a monoatomic gas is brought from state 'A' to state 'B' along path ACB. Temperature at 'A' is 'T0' Heat absorbed along path ACB is equal to

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At 27°C two moles of an ideal monoatomic gas occupy a volume V. The gas expands adiabatically to a volume 2V. Calculate the final temperature of the gas.

[Given 22/3=1.59]

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A cyclic process ABCA is shown in P-T diagram. What would be its P-V graph:

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