Chemistry XII Content
First Law of Thermodynamics
Let the initial volume of the system is V1 and initial internal energy is U1. Let DQP the gas is heated from
|T1 K to T2 K. Addition of heat causes the following changes in the system:|
Internal energy increases from U1 to U2.
Volume of the system increases from V1 to V2.
Temperature increases from T1 K to T2 K.
Work (DW) is done by the gas on the piston.
According to the first law of
DQ = DU+ DW
But DW = PDV
DQP = DU+ PDV
DV = (V2 – V1)
DQP = DU+ P (V2 – V1)
|Graph between P & V for an isobaric process is a straight line which is parallel to V-axis.|