Why does an ideal gas have parallel isotherm and isenthalpic curves?

[ScareCrow271828]

Homework Statement

Why does a gas behave as ideal if the Isotherm and Isenthalp are parallel.

Homework Equations

h=u+pv
T1=T2, P1V1=P2V2

The Attempt at a Solution

[/B]
h1=u1+p1v1, h2=u2+p2v2
h2=h1 so
u1+p1v1=u2+p2v2
and p1v1=p2v2
Does that mean internal energy for an ideal gas is zero?
I don't understand. Thanks in advance!

 

[Chestermiller]

No. It means that u1=u2

 

[ScareCrow271828]

No. It means that u1=u2

Thanks! Why would internal energy be equal for an ideal gas process??

 

[Chestermiller]

Thanks! Why would internal energy be equal for an ideal gas process??

For an ideal gas, the internal energy per unit mass is a unique physical property that depends only on the temperature, irrespective of the process. So, if the temperature is the same, the internal energy is the same.