The Vespiary

The Hive => Newbee Forum => Topic started by: FriendlyFinger on May 10, 2003, 07:25:00 PM

Title: How do you make true, dry, 3M KOH in BuOH?
Post by: FriendlyFinger on May 10, 2003, 07:25:00 PM

If I add 168.33g KOH (3 mol) in 800ml BuOH until dissolved then put in a volumetric flask and fill up with more BuOH, that would not be a 3M KOH in BuOH solution because of that 15% water with some KOH dissolved in it right? How do you get a true 3M solution.

So what do you do, add a drying agent when first dissolving into that 800ml then washing the residue with more BuOH and add to the volumetric flask? I tried that with some 3A sieve beads and it did take up the water and the whole solution was a little less viscous, but I'm not sure how much KOH was left behind or If a 3A sieve is really ok with KOH.

When I added 5%w/v 3A sieve to some plain fresh BuOH it turned a just a little bit brown and hadn't cleared up after a week. And when I was making that 3M solution I heated that same BuOH to get the KOH to dissolve and then It turned brown like tea. Is that normal? Shouldn't it be clear?

OHH, inexperience is such a pain.
Regards,
FF.

Title: Think outside the box.
Post by: terbium on May 10, 2003, 08:21:00 PM

Rhetorical questions:
Why do you need _exactly_ 3M KOH in butanol? How many significant figues of accuracy do you need?

Title: Your right I don't. But how would you if you...
Post by: FriendlyFinger on May 11, 2003, 03:46:00 PM

Your right I don't. But how would you if you wanted to go to sleep with 2 significant figures?

Regards,
FF.

Title: titration
Post by: Rhodium on May 11, 2003, 03:51:00 PM

Then you couldn't do it in any other way than making a solution of approximate strength, and then titrate a sample of the final, dried solution with standardized 0.100 M HCl, using a suitable acid/base indicator, such as BTB.