need to know saturation values of H2O in Pentane 1

[tdw]

the topic says it all, I'm looking for the saturation values of H2O in Pentane at 20 degrees C.
Thanks
Terry

 

[bchoate]

bchoate

Water solubility in pentane at 20 C is 0.01 gram/liter.
WEC

 

[tdw]

.01 gram/liter is the same answer I got from a chemist at GE Infrastructure. My problem is that it differs from the answer I got from tech support at Fisher Scientific by a factor of 10 (.1 gram/liter). Also adding to the confusion is that I don't know if the tech support people at Fisher are talking about parts per unit volume or parts per unit weight. I assume your response of .01 grams/liter is parts per unit weight.

I need to clarify this for a client. Is there a publication where I can find this information in print?

 

[25362]

The formula by NASA for non-olefinic hydrocarbons (from Google):

log mol% = 2 - [4200 (H/C) + 1050](1/T - 0.0016)​

Let's try it out

H/C = 12/60 = 0.2
T = 293 K

mol% = 0.0374 => w/o great error: 0.0374*18/7200 = 9.4*10^-5 on a mass basis = 94 ppm = 0.094 g/kg

 

[tdw]

wow, thanks,
Terry

 

[bchoate]

bchoate

The value comes from the physical properties section of an MSDS.
/

http://www.lomb.com.au/n-Pentane 99.pdf

Bill Choate

 

[25362]

Bill Choate, isn't that the solubility of n-C5 in water, rather than the water solubility in n-C5 ?

 

[TD2K]

Don't you just take 1/solubility in that case 25362? ;-)

 

[EGT01]

My first thought was the MSDS BChoate referenced was indicating solubility of pentane in water. Really seems unclear what they mean when the way they state "Water Solubility" as opposed to their other value seems to imply pentane "solubility in other solvents".

Anyway, checking some other internet references, I found this which is no help but thought I list it anyway. At least it is clear as to whether it is water in pentane or pentane in water.

http://www.personal.psu.edu/faculty/n/x/nxf10/scitab/solvsolu.htm

Here's another link that shows solubility of pentane in water to be 40 mg/liter but that doesn't seem to match anything else I've seen.

http://www.pscanalytical.com/ce/hc-1.htm

I've been trying to get to the NIST website for solubility data but haven't had much luck getting in. I'd be curious to see what it has to compare.

http://srdata.nist.gov/gateway/gateway?dblist=0

 

[bchoate]

bchoate

The MSDS shows the solubility of pentane in water. A question that comes up is why are we straining so hard to find an exact value for this solubility. It would depend on what one is planning to do with the pentane. Whether the solubility is 0.1 gm/l or 0.01gm/l the value is low. Water does not have any appreciable solubility in alkanes since they are do not afford appreciable hydrogen bonding.

If the purpose is to estimate the cost of drying the pentane, either solubility value can be used.

 

[tdw]

I've designed a variation of a Grubbs aparatus for removing water from various chemicals. We're testing with Pentane to determine the efficiency of the new design, so it's important to know where we're starting from. Organometalic chemists in need chemical devoid of water for some of their experiments. The difference between .01 g/l and .1 g/l is significant.

 

[handee]

Well tdw if you're testing a new apparatus, you surely must have a way of measuring the water concentration after treatment (Karl Fisher, etc..). Just saturate some pentane and measure it before and after.

Fran McConville

 

[bchoate]

bchoate

My previous comment that the saturation water concentration is low regardless of whether the magnitude is 0.1 or 0.1 gm/l did not imply that the value was unimportant to the end use. It simply meant that dehydration methods would be the same in either case.

I do have a better value for the saturation water level from a Burdick and Jackson (Honeywell) MSDS. It was clearly stated that the solubility of pentane in water at 68 F is 0.04%. That translates to 0.25 gm/liter.

Even with an issue of this low level of complexity, a persistent problem with posts on this forum is present. Data and information about the application are not given up front. Responders have to pull it out piece by piece. It would be amazing how much better responses could be if the problem were defined well up front.

Pentane is being prepared for use by organometallic chemists who likely need near anhydrous pentane. It seems that there is a new dehydration method to be tested. One post is right on target; why not just measure water by Karl Fischer. Water and pentane could be shaken together to a cloud point and allowed to settle. The pentane layer could be analyzed for water.

There are many ways to get 'dry' pentane. It can be distilled from 3A or 4A molecular sieves or pervaporation can be applied. Anhydrous pentane can be obtained from either Burdick & Jackson or Sigma Aldrich. That material will contain 0.006% water.

WEC

 

[EGT01]

I was finally able to get in to the NIST database.

http://srdata.nist.gov/solubility/

Here's a plot of the data for pentane (1) in water (2)

http://srdata.nist.gov/solubility/figures/fig_37_p44.gif

Here's a plot of the data for water (2) in pentane (1)

http://srdata.nist.gov/solubility/figures/fig_37_p45.gif

From the tabulated data for water in pentane
0.0085 g(2)/100 g soln at 293K

 

[siretb]

I have found 88 ppm (weight) of water in N-pentane

 

[01USU]

Please tell me the density of absolute Sodium Hidroxide at 100 Celcius. Thanx

 

[TD2K]

01USU, you should start a new thread for a question like this as it tends to be overlooked buried in another thread.

Download the DOW caustic soda handbook, it has density information on caustic soda

http://www.dow.com/causticsoda/lit/