Sciencemadness Discussion Board

What are your desiccants?

APO - 10-5-2013 at 02:51

I simply think it would be fun to share which desiccants we each have. The only extremely hydroscopic substance I have currently worth noting is Anhydrous Copper Nitrate.

Lambda-Eyde - 10-5-2013 at 02:54

I only really have calcium chloride and brine... I've also used NaOH in some instances. Need to get some more.
Quote: Originally posted by APO  
The only extremely hydroscopic substance I have currently worth noting is Anhydrous Copper Nitrate.

Did you make this yourself? If so, how did you make it? Also, *hygroscopic

APO - 10-5-2013 at 03:12

I bought the Anhydrous Copper Nitrate from some place in Estonia. I'll post when I attempt to make some though.

confused - 10-5-2013 at 03:18

NaOH when i can my hands on it, otherwise an oven, or just waiting for it to evapourate naturally (which can take ages...especially if there is alot of solvent)

Pyro - 10-5-2013 at 05:01

CaCl2, NaOH, P2O5

elementcollector1 - 10-5-2013 at 05:24

NaOH, H2SO4, CaCl2 (although it's reeeeeally slow)

chemcam - 10-5-2013 at 08:27

My desiccants are CaCl2, NaOH, Activated Alumina, H2SO4, I am in the market for molecular sieves, anyone know a good place to buy or at least get more info? I have looked but do not like the resources I have found.
I almost forgot, I always salvage the desiccator packages that come in consumer products/food. Most common are silica beads and activated carbon.
Quote: Originally posted by confused  
evaporate naturally (which can take ages...especially if there is alot of solvent)

I never have this problem, depending on how much solvent there is just change the size of the evaporating dish.

EDIT: Rewording to sound better

[Edited on 5-10-2013 by chemcam]

woelen - 10-5-2013 at 08:40

Some dessicants I have are

P4O10
CaCl2
NaOH
Na2SO4 (anhydrous)
silica gel
molecular sieves (300 pm)

@APO, I do not believe that you have anhydrous Cu(NO3)2. This chemical is very difficult to prepare and even professional labs usually don't have this chemical in stock, so I would be very surprised if you have the anhydrous compound. Before the 1960's it was thought that anhydrous copper nitrate was not possible and nowadays it is a lab curiousity.

Commercially available copper nitrate is the tri-hydrate or hexa-hydrate. These hydrated compounds are true salts, the anhydrous compound is a volatile covalent compound.

@APO: Is your copper nitrate bright blue like the picture below?

Hexavalent - 10-5-2013 at 13:18

I attest - anhydrous copper nitrate, as woelen pointed out, is a volatile, covalent and strongly nitrating compound and very special conditions are needed to prepare it, as woelen detailed in another thread:
Quote: Originally posted by woelen  

[It involves] dissolving copper in liquid NO2, in which some N2O5 was dissolved. The NO2 was diluted with some solvent (IIRC it was CH2Cl2) in order to make the reaction less vigorous. On evaporation of the solvent, the NO2 and N2O5 at reduced pressure, a solvated solid remains, Cu(NO3)2.xNO2 (I don't remember x anymore, I think it is 2). On careful heating of this solid (at 80 C or so), the NO2 slowly is given off and anhydrous copper (II) nitrate remains.


[Edited on 10-5-2013 by Hexavalent]

APO - 10-5-2013 at 16:09

The Anhydrous Copper Nitrate I have is a MUCH deeper blue than that. I thought it would be white like Anhydrous Copper Sulfate. Once it settles in the bag for a while it becomes hard as a rock!

chemcam - 10-5-2013 at 17:07

Quote: Originally posted by APO  
The Anhydrous Copper Nitrate I have is a MUCH deeper blue than that. I thought it would be white like Anhydrous Copper Sulfate. Once it settles in the bag for a while it becomes hard as a rock!

How do you know it is anhydrous? I have copper nitrate that is very deep blue and it is a hydrate so you can't judge it by color really. I posted a picture of it in the "drying copper nitrate" thread so I don't want to repost it.

If I had anhydrous copper nitrate I can tell you I certainly would not store it in a bag unless it was vacuum sealed or under inert atmosphere. Preferably in an ampule since I would add it to my rare chemical compounds collection. If it is exposed to air it is not anhydrous anymore.

APO - 10-5-2013 at 17:23

I'm pretty sure it's under Argon.

GammaFunction - 11-5-2013 at 01:56

Quote: Originally posted by chemcam  
I am in the market for molecular sieves, anyone know a good place to buy or at least get more info?


I inquired about a group purchase of sieves. Nobody was interested. My problem is that I'm at a place where shipping is expensive unless USPS, but most companies do UPS.

deltaadsorbents.com has good prices in bulk; $4/lb at 25 lbs. Redistribute by medium flat rate boxes, and you've got a good group buy deal.

Also, the CRL glass-window sieves on Amazon are apparently 3A.

Incidentally, some kinds of kitty litter are silica gel. I've thought of getting it to protect my tools.

[Edited on 11-5-2013 by GammaFunction]

woelen - 11-5-2013 at 02:16

Quote: Originally posted by APO  
The Anhydrous Copper Nitrate I have is a MUCH deeper blue than that. I thought it would be white like Anhydrous Copper Sulfate. Once it settles in the bag for a while it becomes hard as a rock!
Well, then it is not anhydrous. Anhydrous copper nitrate is not blue, it is fairly dark green with a bluish hinge.

You can easily confirm the presence of water in your material. Take a test tube, put appr. half a gram of solid in it and carefully heat above a flame. You'll see formation of copious amounts of red fumes and droplets of nitric acid will collect in the cooler places of the test tube. The test tube will get a frosty appearance.

Another indication of your copper nitrate being hydrous is the mere fact that you could buy it. A 13-year old boy will not have the money to purchase anhydrous copper nitrate. I do not know exact prices for that, but I think that a few hundreds of grams of that material will cost you a little fortune.

[Edited on 11-5-13 by woelen]

Fantasma4500 - 11-5-2013 at 03:25

apparently many have CaCl2.. i see why.. its of what ive seen better than NaOH, it doesnt decompose on strong heating and its not melting or etching anything (alike NaOH) also its easy to get a hold of..

Eddygp - 11-5-2013 at 04:27

I use NaOH. I can't have access to anhydrous CaCl2 and for most reactions I do, NaOH is more than enough.

Finnnicus - 11-5-2013 at 04:45

My pool grade CaCl2 is good, but not preferable.

Thebrain - 11-5-2013 at 05:36

If there's a better dessicant than phosporous pentoxide, I can't even imagine it.

blogfast25 - 11-5-2013 at 06:39

Has anhydrous MgSO4 been overlooked here? From Epsom Salt, this is OTC, cheap and cheerful and useful to dry organic liquids with.

Metacelsus - 11-5-2013 at 14:18

Anhydrous MgSO4 is what I use. Just heat up the epsom salt (on a hotplate or in the microwave). It's great for organic workups.

[Edited on 11-5-2013 by Cheddite Cheese]

APO - 11-5-2013 at 17:17

According to this "Anhydrous copper nitrate forms deep blue-green crystals and sublimes in a vacuum at 150-200 °C." it fits color specifications. Any way to test if it's truley anhydrous? I got it from eBay seller argon242.

chemcam - 11-5-2013 at 17:27

Ok you can test how by the above mentioned method, but be sure you open the sealed bag in a water free, inert atmosphere like a sealed glove box or similar.

APO - 11-5-2013 at 17:50

Sorry, skimmed over that. I'll start building an inert atmosphere glove box.

chemcam - 11-5-2013 at 18:05

Quote: Originally posted by APO  
Sorry, skimmed over that. I'll start building an inert atmosphere glove box.


That is actually a really good idea, it is a fun project and will have many uses, it is also something you can achieve with your skill level. Posts like that get you respect.

DubaiAmateurRocketry - 12-5-2013 at 02:52

Lithium compounds are extremely hygroscopic as well, more than copper nitrate.

woelen - 12-5-2013 at 02:59

I found the anhydrous copper nitrate from this seller.

http://www.ebay.nl/itm/Copper-II-nitrate-anhydrous-reagent-9...

The picture he shows with the petri dish is exactly like the material I have. Mine, however, is sold to me as the tri-hydrate and this color indeed fits the tri-hydrate very well.

The seller may tell that it is anhydrous, but I do not believe that, unless you can really show that it is anhydrous. Heat some of the material in a test tube and see if droplets of nitric acid and/or water are formed.

APO - 12-5-2013 at 13:24

Would setting it in open air and tracking how much mass it gains provide usable data?

woelen - 14-5-2013 at 03:23

No, that does not tell you anything. It will attract much more water than is present in the tri-hydrate or six-hydrate. It will continue attracting water until it dissolves in it.

[Edited on 14-5-13 by woelen]

MrHomeScientist - 14-5-2013 at 06:05

In order of frequency, I use KOH, CaCl2, and NaOH. I like KOH because of its strength as a dessicator, and I have more of that than NaOH at the moment. Anhydrous CaCl2 (or possibly the monohydrate) is found in nearly every store around here as Damp Rid moisture absorber, since I am in a humid area. It's not quite as good as the hydroxides, but I have a near limitless supply!

Bot0nist - 14-5-2013 at 06:18

KOH
H2SO4
CuSO4 (I like the color change from anhydrous to pentahydrate)
DampRid
MgSO4
These are what I use frequently, some other more special ones are used rarely.

Endo - 14-5-2013 at 07:24

I have some MgClO4, MgSO4, H2SO4, Anhydrous CuSO4.

ItalianChemist - 15-5-2013 at 07:06

I usually use NaOH as a desiccant. It's very hygroscopic and cheap!
The most hygroscopic compound I've ever seen is vanadyl sulfate.

ElectroWin - 2-6-2013 at 10:31

Quote: Originally posted by APO  
According to this "Anhydrous copper nitrate forms deep blue-green crystals and sublimes in a vacuum at 150-200 °C." it fits color specifications. Any way to test if it's truley anhydrous? I got it from eBay seller argon242.


use something that reacts with water?

APO - 4-6-2013 at 04:21

Well, I have lithium, but that may oxidize just from contact with the Copper Nitrate.

Sulaiman - 25-5-2016 at 03:02

I have used;
Na
P2O5
H2SO4
NaOH
CaCl2
MgSO4
Vacuum

Eddygp - 25-5-2016 at 03:35

MgSO4 in organic chemistry is just bliss.

careysub - 25-5-2016 at 06:11

Quote: Originally posted by SnehaPatel  
The advent of molecular sieves into the purification and desiccation industry has helped to improve the processes while reducing costs. Molecular sieve 5a, with a pore size of 5 Angstroms, presents a special advantage with its alkali amino silicate structure. Its drying and purification uses stretch from industrial natural gases to industrial liquids. visit for more info http://molecularsievedesiccants.com/


Since you represent a mol sieve supplier, and took the time to post here about your business, do you care to quote terms for a bulk buy for members here? The issue of obtaining reasonably priced mol sieves comes up regularly.

Trevor9424 - 25-5-2016 at 10:19

I've only used NaOH so far, but I do plan to try to use CuSO4 and MgSO4.

Question:
Can cobalt(II) chloride be used as a desiccant or would it not work or be ineffective? The reason I'm asking is because I don't have a lot of use for cobalt chloride and I want to try to explore more of its uses.

unionised - 25-5-2016 at 12:48

Ice.

it's not great- but it's easy to get and it's cheap.
Blowing air over ice then warming it up to room temperature will cause the humidity to drop to about 25% which is fairly dry.
If you need drier air that that, you can still usefully start with ice to strip out the bulk of the water.

100PercentChemistry - 25-5-2016 at 13:40

I use annahydrous CaCl2 or NaOH.

100PercentChemistry - 25-5-2016 at 13:42

I use annahydrous CaCl2 or NaOH.

JJay - 25-5-2016 at 16:49

I have a lot of dessicants... the one I use most is calcium chloride.

XeonTheMGPony - 25-5-2016 at 17:18

NaOH, H2SO4, CaCl2, Silica gel (Blue indicating), MgSO4 (Anhydrous), Vacuum pump (Mechanical desiccator)

Working on building a vacuum freeze drying system one of these days it'll be finished!

Eddygp - 30-5-2016 at 04:15

Not a desiccant per se, but I have a small vial with tetraethylammonium tetrachlorocuprate(II) and it is very deliquescent. So much that just by standing inside a fairly air-tight screw vial, it has started to get slightly more crumbled together, as if it was slightly moist sand.

Btw, 200th post in Chemistry in General.

Wow

Panache - 13-6-2016 at 03:08

It's been sometime since I have felt some input of mine may be helpful.

Firstly
For dessicator boxes, of whatever form, simplest is CaCl2, simplest and best is CaO, best overall is p2o5
For solvents mol sieves are completely OTC.
Go to a refrigeration mechanics trade store, in Australia something like a HeatCraft. Go to the drier cores section.
Find the brand on sale that week/month/whatever.
Find the drier core that only does drying(as opposed to drying + acid adsorption etc)
Buy it
At home smash it to pieces with a hammer
Place chunks of it into your acetone/ethanol/etc solvent bottles
An eon ago Rhodium mentioned this technique, it is very sound, refrigeration mol sieves are 3A, small enough pores to not adsorb acetone.
Solid NaOH, great for amines and all carbons (ref Vogel 1956)

Wow I posted again!!

j_sum1 - 13-6-2016 at 04:55

Great to see you, Panache.
Your last four posts were nine months apart. Don't leave it so long. :)