- #1
dUDEonAfORUM
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In a isobaric process W=PΔV
I
Given the change in temperature and pressure is constant to find heat added to an mono-atomic ideal gas we use
Q=ΔU + W = 3/2 nRΔT + PΔV = 3/2 nRΔT + nRΔT
so Q=5/2 nRΔT correct?
II
But given the heat added to an ideal gas, constant pressure that acts on the gas, and change in volume
To find ΔU we have to use ΔU = Q-W = Q-PΔV
and using ΔU = 3/2 PΔV (based on PΔV=nRΔT ) is incorrect I was told this is so because P in PΔV=nRΔT is the pressure of the ideal gas and not the pressure acting on the ideal gas, is this explanation true?So why does PΔV= nRΔT hold true in the I and not in II ?
I
Given the change in temperature and pressure is constant to find heat added to an mono-atomic ideal gas we use
Q=ΔU + W = 3/2 nRΔT + PΔV = 3/2 nRΔT + nRΔT
so Q=5/2 nRΔT correct?
II
But given the heat added to an ideal gas, constant pressure that acts on the gas, and change in volume
To find ΔU we have to use ΔU = Q-W = Q-PΔV
and using ΔU = 3/2 PΔV (based on PΔV=nRΔT ) is incorrect I was told this is so because P in PΔV=nRΔT is the pressure of the ideal gas and not the pressure acting on the ideal gas, is this explanation true?So why does PΔV= nRΔT hold true in the I and not in II ?