×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

need to know saturation values of H2O in Pentane

need to know saturation values of H2O in Pentane

need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

[u]bchoate[/u]

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

RE: need to know saturation values of H2O in Pentane

(OP)
.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?

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

(OP)
wow, thanks,
Terry

RE: need to know saturation values of H2O in Pentane

bchoate

The value comes from the physical properties section of an MSDS.
/www.lomb.com.au/n-Pentane%2099.pdf

Bill Choate

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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.

RE: need to know saturation values of H2O in Pentane

(OP)
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.

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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

RE: need to know saturation values of H2O in Pentane

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/

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources