- **New Users**
(*http://physicshelpforum.com/new-users/*)

- - **How do I determine the amount of water in a sealed container to create a given pressu**
(*http://physicshelpforum.com/new-users/12339-how-do-i-determine-amount-water-sealed-container-create-given-pressu.html*)

How do I determine the amount of water in a sealed container to create a given pressuI have a sealed container with a volume of 1 liter. I want to go from an initial pressure of p1=1 atm and an initial temperature of T1=298 to a final pressure of p2=10 atm and a final temperature of T2=453 K. I want to to use water to create the pressure. But I do not know how to determine the amount of water, how would I do that? Thanks. |

You can set up two equations in two unknowns: 1. For the initial condition you have gaseous air plus liquid water in the container. The number of moles of air from the Ideal Gas law is: $\displaystyle n_{a} = \frac {P_1 V_{a}}{RT_1} $ where $\displaystyle n_a$ is the number of moles of air and $\displaystyle V_{a}$ is the volume of air in the container. The volume of water at this stage is then $\displaystyle V_{w} = V - \rho_{w} n_w $ where V = size of the container or 1 liter and $\displaystyle \rho_w$ is the density of water in terms of liter/mole. Combining these two equations: $\displaystyle n_a = \frac {P_1(V-\rho_w n_w)}{R T_1} $ 2. The second equation is at the higher temperature, when the water has turned to gaseous steam. From the Ideal Gas law: $\displaystyle n_a + n_w = \frac {P_2 V}{R T_2} $ So now you have two equation with unknowns $\displaystyle n_a $ and $\displaystyle n_w$. |

All times are GMT -7. The time now is 03:24 AM. |

Copyright © 2016 Physics Help Forum. All rights reserved.

Copyright © 2008-2012 Physics Help Forum. All rights reserved.