Final pressure when water is injected into a closed tank of vapor

[matt222]

Homework Statement

Calculate the final pressure of the closed tank containing vaper if it is filled with a water.If the water mass is 400,000 kg is injected into the tank, initial tank pressure is 1bar and the volume is 80,000m^3, density of the vapor 1 kg/m^3 at 1 bar, treat the air and water as ideal gases.

Homework Equations

The Attempt at a Solution

Volume before V1=80,000m^3
Volume after V2=480,000m^3
initial pressure = 1 bar

final pressure is going to be 0.167 bar, but the question is asking me that with the same tank how much the pressure is going to be and in this case my answer is wrong!

as the volume increase it is normal that the pressure will decrease but if we have a fixed tank!

I really confused!

 

[matt222]

I think something ring in my head!

Since the initial volume is before V1=80,000m^3
Volume after V2=480,000m^3

if we take the ratio of it V2/V1= 6 in this case the pressure for the same tank is going to be 6 bar! is it true

 

[matt222]

I need a help please