Air is compressed (in a piston cylinder device) isothermically from 100kpa and 30°c to 300kpa. on a per unit basis, compute: a) the amount of work that flows into the air. b) the change in energy of the air. c) the amount of heat that flows out of the air.

a) w= -95.53 KJ

b)Q= -95.53

Explanation:

At initial condition

At final condition

a)

It is constant temperature process so PV=C

So work in constant  temperature process  

  or

For air  

T is temperature in Kelvin.

KJ

So w= -95.53 KJ ,This is work for unit mass.

Negative sign indicates , it is compression process.

b)

If take air as ideal gas then We know that internal energy for ideal gas is a function of temperature only.Here process is a constant temperature process so temperature of air will remains constant so ,change internal energy of air is equal to zero.

c)

From first law of thermodynamics

Q=+W

Here

So Q=W       ( w= -95.53 KJ )

⇒Q= -95.53 KJ

Negative sign indicates that heat flows out of the air.