Plotting H2O Pressure vs Volume w/ Van Der Waals Gas Equation

[ja87]

Homework Statement

i must use van der waals gas equation to plot a pressure against volume graph for H2O. i must do 3 plots on one graph, one of the critical temperature given a point of inflection, one where temperature is less than the critical temperature giving a large dip in the graph, and one where T>critical temperature and hence gives a a curve where dp/dv is never =0.

Homework Equations

i have the van der waals equation :(p+a(1/v)^2)*(v-b) = n*R*T
and have rearranged to make p=-(-a(1/v)^2*v+a(1/v)^2*b+n*R*T)/(-v+b)
i also have a=0.5507, b=3.04*10^-5, R=8.314, n=1

The Attempt at a Solution

i have tried to plot a p(v) graph with these values in this equation (using Maple) using small, large and negative values for T and all i get is a graph that looks like a 1/x graph, i cannot get the desired dip for when T<critical temperature. am i using the wrong equation or are my numbers wrong.

 

[Jhero]

Thank you for your post. It seems like you are on the right track with using the van der Waals equation to plot a pressure vs. volume graph for H2O. However, there are a few things that may be causing your graph to not match your expectations.

Firstly, it is important to note that the van der Waals equation is an approximation for real gases and may not accurately represent the behavior of all gases, including H2O. Therefore, your graph may not perfectly match your expectations.

Secondly, it is important to double check your calculations and make sure you are using the correct values for a, b, R, and n. It may be helpful to double check your calculations with a different source or to ask a colleague to review them.

Finally, it may be helpful to plot your graph using a wider range of values for volume, as well as a wider range of temperatures. This may help to better visualize the behavior of the gas at different temperatures and volumes.

I hope this helps and good luck with your plotting!