Question

when an ideal gas is compressed adiabatically and reversibly the final temperature is higher or lower than initial temperature?

Answer 1

When an ideal gas is compressed adiabatically and reversibly, the final temperature is higher than initial temperature.  

This can be proved by using 1st law of thermodynamics:

dq = dU + dW

In a adiabatic process,

dq =0

So,

dU = -dW

As work is done on the gas , then dW is negative

That means dU is positive

As  

dU = Cv × dT  

As dU is positive , then temperature must be increased .

So, When an ideal gas is compressed adiabatically and reversibly, the final temperature is higher than initial temperature.  

Answer 2

Answer:

The final temperature is higher than the initial temperature