dobeid
Harmless
Posts: 7
Registered: 19-9-2008
Member Is Offline
Mood: No Mood
|
|
How do I make a sodium hydroxide solution from caustic soda?
Hi:
I need to mix up a strong lye solution to bring an acidic mixture to a pH of 14. I have the caustic soda (NAOH) but am confused as to how much
distilled water to add to how many grams of caustic soda to create the strong lye solution that I need.
If anyone can educate me on this I would be most appreciative.
Thanks
[Edited on 8-11-2008 by dobeid]
|
|
|
crazyboy
Hazard to Others
Posts: 436
Registered: 31-1-2008
Member Is Offline
Mood: Marginally insane
|
|
NaOH+H2O=>sodium hydroxide soloution.
Caustic soda is sodium hydroxide which is NaOH. Just add sodium hydroxide to water until it is at the correct pH.
|
|
|
dobeid
Harmless
Posts: 7
Registered: 19-9-2008
Member Is Offline
Mood: No Mood
|
|
Thanks Crazyboy.
|
|
|
chief
National Hazard
Posts: 630
Registered: 19-7-2007
Member Is Offline
Mood: No Mood
|
|
Watch out: I gets hot, sometimes beyond boiling point, and may spit around the hot and dangerous (at least to the eyes) NaOH-solution ! Wear
protective glasses, or don't do it !!!!
|
|
|
Nerro
National Hazard
Posts: 596
Registered: 29-9-2004
Location: Netherlands
Member Is Offline
Mood: Whatever...
|
|
pH 14 = pOH 0 which means you need 1M NaOH in water. -log(1) = 0, conversely 10<sup>-0</sup> = 1/10<sup>0</sup> = 1/1 = 1 
And, always add acids and bases to water, never the other way around, that way theres not so much acid/base splashing about.
#261501 +(11351)- [X]
the \"bishop\" came to our church today
he was a fucken impostor
never once moved diagonally
courtesy of bash
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
I have seen an eye splashed with NaOH solution. You DON't want that........
|
|
|
Klute
International Hazard
Posts: 1378
Registered: 18-10-2006
Location: France
Member Is Offline
Mood: No Mood
|
|
The proper procedure would be to gradually add NaOH pellets to a very well stirred, cooled volume of distilled water.
Do not be afraid of taking your time, even 20min, NaOH pellets liberate large amounts of heat when they dissolve, and there can be a latency, as it
takes a little moment to heat up, and then as more dissolves, the heating increases, often to over 100°C!
So do it slowly, and with very good stirring!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
|
|
|
smuv
National Hazard
Posts: 842
Registered: 2-5-2007
Member Is Offline
Mood: Jingoistic
|
|
I like to prepare sodium hydroxide solutions in plastic cups, as sodium hydroxide has a tendency to fuse itself to the bottom of Pyrex glassware.
Just a little tip.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
|
|
|
Picric-A
National Hazard
Posts: 796
Registered: 1-5-2008
Location: England
Member Is Offline
Mood: Fuming
|
|
I used to remove lightly fused NaOH form glassware by covering the fused mass with water and slowly adding conc HCl..
I have heard a dilute soloution (around 5%) works wonders for cleaning fused solids off glassware.... never tried it myself though.
|
|
|
Nerro
National Hazard
Posts: 596
Registered: 29-9-2004
Location: Netherlands
Member Is Offline
Mood: Whatever...
|
|
To be honest when I'm in a lab I usually just dump the pellets in water and let it stir for a while. As long as it's in a fumehood and off to the side
nothing is really going to happen. Obviously you should ALWAYS wear glasses and keep your head out of the fumehood.
So long as you THINK about what you're doing you'll be fine.
#261501 +(11351)- [X]
the \"bishop\" came to our church today
he was a fucken impostor
never once moved diagonally
courtesy of bash
|
|
|
smuv
National Hazard
Posts: 842
Registered: 2-5-2007
Member Is Offline
Mood: Jingoistic
|
|
| Quote: | | I used to remove lightly fused NaOH form glassware by covering the fused mass with water and slowly adding conc HCl.. |
In my experience there is still a blemish left on the glassware even after washing with acid, because the spot where the pellet gets fused gets
etched. Best to avoid the problem altogether and use plastic...
[Edited on 11-9-2008 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
|
|
|
chemrox
International Hazard
Posts: 2961
Registered: 18-1-2007
Location: UTM
Member Is Offline
Mood: LaGrangian
|
|
| Quote: | Originally posted by Jor
I have seen an eye splashed with NaOH solution. You DON't want that........ |
what happened? In general bases are much worse than acids on eyes and skin
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
|
|
|
Jor
National Hazard
Posts: 950
Registered: 21-11-2007
Member Is Offline
Mood: No Mood
|
|
Yes I know it's very late  Can't sleep!
I didn't see it in real life, but on a picture. Our lab assitent wanted to show us to show us how dangerous chems can be.
Well the eye was gone, it had turned into a slurry. Just red flesh was left, like a hole. It was a mess. According to one of the professors, getiign
a base like NaOH conc. in the eye will mean almost certain blindness, while with acids there is still hope.
|
|
|
crazyboy
Hazard to Others
Posts: 436
Registered: 31-1-2008
Member Is Offline
Mood: Marginally insane
|
|
| Quote: | Originally posted by Klute
The proper procedure would be to gradually add NaOH pellets to a very well stirred, cooled volume of distilled water.
Do not be afraid of taking your time, even 20min, NaOH pellets liberate large amounts of heat when they dissolve, and there can be a latency, as it
takes a little moment to heat up, and then as more dissolves, the heating increases, often to over 100°C!
So do it slowly, and with very good stirring! |
How big are your pellets? It seems like people are talking abut chunks of NaOH about the 1 cm long correct? Strange I have only found it very small
prills.
|
|
|
MagicJigPipe
International Hazard
Posts: 1554
Registered: 19-9-2007
Location: USA
Member Is Offline
Mood: Suspicious
|
|
My experiences with NaOH differ slightly. Whenever I add water to NaOH pellets (just enough to dissolve them completely) it gets hot but hardly ever
heats up over 60*C. Why is that?
Also, there is never any splashing/boiling.
And the boiling point of NaOH solution is greater than 100*C (and much more if it is saturated).
[Edited on 11-10-2008 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
|
|
|
UnintentionalChaos
International Hazard
Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline
Mood: Nucleophilic
|
|
MagicJigPipe- Try splashing a little water onto a pile of prills and there will be quite a bit of nasty steam coming out of the vessel. I have a HDPE
jar with a liquid tight lid that I shake the prills in while they dissolve so Im not stirring a huge lump at the bottom of a container but I need to
open it repeatedly to relieve pressure and afterwards, it is sometimes too hot to touch.
crazyboy- Standard lab grade stuff is usually half-oval shaped pellets between 3/4 and 1 cm long. The drain cleaner stuff is almost universally flakes
or tiny round pellets.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
|
|
|
Klute
International Hazard
Posts: 1378
Registered: 18-10-2006
Location: France
Member Is Offline
Mood: No Mood
|
|
Well, no they are quite small pellets (0.5 cm wide, 0.2cm high), and pouring water directly on them causes a hell of a mess, often fusing to the
bottom of the glass immediatly...
The solution itself doesn't boil indeed, but gets superheated at some points, where it ca,n sizzle and splash everywhere... and you have to wait
10min in a ice bath to get it to room temp anyway, so might just aswell take 10min to prepare the solution, which will be ready and a room temp, with
much less carbonaet formation IMHO.
Directly adding water to NaOH (or conc acid BTW) is a very dangerous thing to do. I do not see any advantage to it either.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
|
|
|
Foss_Jeane
Harmless
Posts: 40
Registered: 14-5-2008
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by MagicJigPipe
My experiences with NaOH differ slightly. Whenever I add water to NaOH pellets (just enough to dissolve them completely) it gets hot but hardly ever
heats up over 60*C. Why is that? |
Because you've been damned lucky so far. I wouldn't push it.
Why do you think "Red Devil Lye" makes such a good drain opener? As soon as the pellets hit the water in the goose neck, it gets very hot --
hot enough to melt the grease and other gunk that got stuck down there. Even then, gitdahellawayfromdere! It can boil over and come shooting back up
the drain.
I always add the NaOH or KOH flakes/prills to cold water with the beaker sitting in an ice water bath. So it takes time to prepare
concentrated solutions. What's better: waiting 20 mintes for your solution, or living the next 50 years blind as a bat?
P.S. Since we're on the subject, NH4OH safety: chill the bottle before you open it. That way, you cut down the pressure so it won't shoot out a nasty
cloud of ammonia. Allow to warm up to room temp with the cap cracked so that you don't have an increase of air pressure as it warms. That sort of
defeats the purpose. Of course, you wouldn't be using this stuff unless you had a fume cubboard, right?
Need I say goggles, goggles, goggles?
[Edited on 22-11-2008 by Foss_Jeane]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
