Calculate the change in internal energy of a gas kept in a rigid container when 100 J of heat is supplied to it.

Given


Heat supplied ΔQ = 100J


From first law of thermodynamics, we know that,


ΔQ=ΔU+ΔW


Where ΔQ=heat supplied to the system


ΔU=change in internal energy


ΔW=work done by the system


We know that,


Work done = force ×displacement



Volume = areadisplacement


Therefore,


Work done=pressure ×volume


Let change in the volume of system = ΔV = V2-V1


Pressure =P


Thus, work done by the gas


ΔW=PΔV


Since the gas is kept in a rigid container, therefore ΔV=0 in this case.


So, ΔW=0


Thus, first law will become


ΔQ=ΔU = 100J


change in internal energy will be 100J.


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