[nertil1]

This is related to my previous two posts. I have a surge drum that contains a liquid that is mostly heptane and a vapor that is mostly methane. I need to find out how much I have of each. I know the pressure and temp. To find this out, I will find the molar volume of heptane and methane using the peng robinson equation and then find the volume of liquid and vapor. To find the moles of heptane, I will divide the volume of liquid by the molar volume of heptane to get moles of heptane. I will do something similar for the methane vapor to get moles of methane. I want to know if this is okay or not, or if I need to change my thinking here?

Thanks
nertil

[technologist]

I will find the molar volume of heptane and methane using the peng robinson equation and then find the volume of liquid and vapor

How will you find the volume without knowing no of moles from molar volume.

So first specify the parameters which are known then it can be worked outproperly. you need to run on trial & error and use VLE also to know the x & y for each component.

[nertil1]

Sorry I wasn't clear about that. I know that the drum dumps all its contents whenver the liquid level reaches 8 inches. so by some math, I should be able to find the volume of the liquid and then subtract that from the total volume to find the volume of vapor.

[technologist]

Then you already know liquid heptane vol (as you said it is 8") by calibration of tank & remaining volume of vapors of methane.
So you can find out no of moles as per your earlier thinking.