antimon
Harmless
Posts: 33
Registered: 24-6-2015
Member Is Offline
Mood: No Mood
|
|
Is this right? Tap water in a chemical reaction?
Hi, i downloaded a pdf thats called 'Kings chemistry something' by a guy called Jared Ledgard.
In it on page 41 he describes a electrochemical reaction, making Chloroform from rubbing alcohol, Potassium Dichromate, pickling salt, H2SO4, and tap
water.
Can this really be correct? I would have thought that all the chemicals thats added in the water coming out of our tap would mess up the reaction.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
The contaminants in your tap water could help or hinder the reaction - no idea which.
Distilled water is generally used simply so you know what is in the reaction mixture.
Given that the Haloform reaction works fine, it would seem a waste of sulphuric acid and potassium dichromate to me.
Do you have a reference to this pdf you downloaded ?
If not, please put any unreferenced questions in the Beginnings topic, where they belong.
|
|
|
Texium
Administrator
Posts: 4516
Registered: 11-1-2014
Location: Salt Lake City
Member Is Offline
Mood: PhD candidate!
|
|
Or even better, post it to the Short Questions Thread in miscellaneous instead.
Really it would depend on the tap water that you have, and on the context of how the pdf wants you to use it.
|
|
|
gdflp
Super Moderator
Posts: 1320
Registered: 14-2-2014
Location: NY, USA
Member Is Offline
Mood: Staring at code
|
|
Here's a link to the book the OP is talking about. http://catbull.com/alamut/Bibliothek/Kings_Chemistry_Surviva...
To answer your question, the amount of dissolved salts in tap water is quite low. Seeing as you distill the chloroform after removing it from the
cell, there is no chance of contamination due to using tap water. Typically, tap water contains mainly a few salts, and metal ions will be plated out
early in the electrolysis and any chloride contamination will not interfere with the reaction, seeing as you are already adding sodium chloride.
aga, the potassium dichromate is only present in catalytic amounts, it's not being used to oxidize the isopropyl alcohol to acetone.
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
Thanks gdflp.
Without knowing anything about the Process i was mostly lost in space.
The bleach + acetone route still seems so much simpler.
|
|
|
gdflp
Super Moderator
Posts: 1320
Registered: 14-2-2014
Location: NY, USA
Member Is Offline
Mood: Staring at code
|
|
I agree, unless the OP can't buy bleach.
|
|
|
Dan Vizine
National Hazard
Posts: 628
Registered: 4-4-2014
Location: Tonawanda, New York
Member Is Offline
Mood: High Resistance
|
|
Tap water has an undeservedly bad reputation for unsuitability for reaction use. I've run 90% of reactions, extractions, washings with tap water and
it has no detectable ill effects.
There are reactions where it matters what grade the water is. For diazonium salt reactions, or a sol-gel polymerization, or a final recrystallization
of a product, etc. I'd use deionized water. Our lab never had distilled water, and we made experimental drugs for NCI & Walter Reed.
Only once, when Monsanto wanted a pile of N-methylphosphono acetic acid purified (PALA to them, Round-up to you after they add an amine to make a
salt) did we actually purchase water, HPLC grade, no less. They wanted kilos multiply recrystallized from this pure water for toxicology purposes. It
was my first and last time using round-bottom flasks of 50 L and larger.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
|
|
|
Boffis
International Hazard
Posts: 1836
Registered: 1-5-2011
Member Is Offline
Mood: No Mood
|
|
Returning to the question of using tap water in reaction you need to consider what you are planning to do and will the components of the water cause a
problem. The main "problem" components are Ca and Mg since they often form insoluble precipitates with many inorganic and organic acids (eg soap scum
in hard water areas). Where I live the water is exceedingly soft and the main problem components are chloride and sulphate probably derived from sea
spray carried inland by the prevailing winds but these are generally only a problem if I am using silver and barium solutions when they cause the
solutions to become cloudy. Interestingly I have found that much "de-ionised" water has too high a chloride ion content to be used with silver nitrate
and I have to resort to distilling water for this purpose. In the OP specific situation I can't see any problem using tap water unless you live in a
very hard water area when you might get a ppt of calcium sulphate forming, though this should not be a big problem on an amateur scale.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
