Air(ideal gas) at 292.15k is expended by a piston from 600cm^3 to 900cm^3 at a temperature of 550k at 900kpa pressure. find the pressure before expansion.

The pressure before expansion is 717.1 kPa.

Explanation:

We need to use the Ideal Gas equation to find the initial pressure:

Where:

P: is the pressure

V: is the volume

n: is the number of moles

R: is the gas constant

T: is the temperature

Since the number of moles does not change after the expansion, we need the following number of moles:

 (1)

Where "f" is for final

Before the expansion, the pressure is:

  (2)

By entering equation (1) into (2) we have:

Therefore, the pressure before expansion is 717.1 kPa.                  

I hope it helps you!        

that would be b i just took the test : )