If I choose conditions at other points, I have to figure out how I want to interpolate/extrapolate from the tabulated values to my chosen conditions.ġb) Or, perhaps you have a mathematical model to describe the VLE of H2SO4 - maybe an activity coefficient equation with chemical equilibrium equations and ionization equations and so on. If I choose conditions at any one of the tabulated points, I can read the partial pressures off of the table. What kind of data do you have for H2SO4 VLE?ġa) The data I have for H2SO4 is in from Perry's and is in a tabulated format - partial pressure of each species at different temperature and composition values. Here's what I would expect:ġ) get partial pressure of each component in the vapor phase.

I'm sure we can help with the computational steps. So, I think we can help with understanding how to perform the computation, but I don't know that we can help with the real world chromic acid application of the calculation. However, the final, quantitative results of the calculations will only be as meaningful as the raw input data we feed into the computational sequence. Maybe even change the problem to sulfuric acid instead of chromic acid (since I know there is VLE data for sulfuric acid) until the computational steps are understood. If you need help figuring out the steps to the computation, we can probably help you work through the computational steps. We might be able to help - it depends on what you need help with. It seems to me that the tank would need to be sealed in some way to maintain that pressure. At 250 C, Perry's data for sulfuric acid suggests a bubble point pressure of about 30 bar. I would also note that 250 C in an 'open' tank seems high - unless I am misunderstanding what an open tank is. Is the same true for chromic acid? For your purposes, does it matter (it might be enough to combine all 'chromic acid species' and not worry about the individual species that make up 'chromic acid' in the vapor)? Your last post suggests that you might even be extending further to mixtures of sulfuric and chromic acid (and dichromates? anything else?). According to the data in Perry's for sulfuric acid, there is both SO3 and H2SO4 in the vapor - generally more H2SO4 than SO3. So, Here chromic acid means, chromium trioxide (CrO3) only?. Are you certain that there is VLE data for chromic acid to be found in the literature?Įdited by MrShorty, 14 March 2018 - 12:22 PM.

I believe one can also search through the documentation for your favorite simulator to get at the source data (if any) used by the simulator for a given system. (I could readily find sulfuric acid water VLE in both data banks, but could not find any VLE for chromic acid water). However, if you want to see the data, they require that you pay for that information. They will allow you to search their available systems for free. There is a bit more to this than when one is talking about a simple hydrocarbon.Īmong the databases that I use are the Dechema Data Bank and the Dortmund Data Bank.

Are you looking for total bubble point pressure only? Or partial pressure of H2CrO4? Or partial pressure of CrO3? The point is, one does not simply talk about the vapor pressure of chromic acid. The concept of vapor pressure also changes significantly.

There is quite a jump in concept from 'VOC' meaning a simple pure hydrocarbon like benzene to 'VOC' meaning 'an inorganic electrolyte - almost certainly an aqueous solution (since I don't believe pure H2CrO4 readily exists)'.

Chromic acid cro3