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 1 
 on: Today at 12:13:56 PM 
Started by an3urysm - Last post by Arkcon
That's the take home message.  You courses may start asking you to identify the properties of compounds, and you'll want to get it straight.

For taste, the way I'd heard it originally, was that the chloride ion binds to specific tongue receptors, therefore all chlorides have a salty taste -- NaCl, KCl with a bitter aftertaste, even HCl (very diluted and don't try this at home kids) along with other tastes.  Alas,. I've sine learned I had the concept backwards: Ref - https://en.wikipedia.org/wiki/Taste#Saltiness

 2 
 on: Today at 12:08:28 PM 
Started by O Cabra - Last post by O Cabra
Yes thats what i was thinking. So in that case it would be a C2 point group right?

 3 
 on: Today at 11:57:47 AM 
Started by paulhao - Last post by Babcock_Hall
Could the pieces of glass that are scratched off be the sites of heterogeneous nucleation?  One tries to avoid heterogeneous nucleation in some applications, but I don't see why it would matter in the context of an organic recrystallization.

 4 
 on: Today at 11:48:42 AM 
Started by O Cabra - Last post by Corribus
I believe there's a C2 axis, but it's really hard to picture.

Here's a way: take the index fingers of your two hands and make an X with them right in front of your face so you are looking right where your fingers cross. Imagine the fingernails are the two chlorine atoms. Do you see it now?

 5 
 on: Today at 11:43:02 AM 
Started by Babcock_Hall - Last post by Babcock_Hall
I used copper sulfate to remove lutidine or collidine a long time ago, but I had not thought about employing it here.  It might not work, in that the product may be too water-soluble.  As far as having water in the recrystallization, can you explain your rationale?  This is a very old paper, and I have found one error so far (the amount of pyridine); therefore, I am not opposed to deviating from the protocol.  I am not entirely sure how I would.

One trick that has worked for me in the past is ion-exchange chromatography using a gradient of triethylammonium bicarbonate.  I am thinking it might be time to dust off that trick again.

 6 
 on: Today at 11:38:07 AM 
Started by paulhao - Last post by Babcock_Hall
Are we talking about an aqueous solution or a non-aqueous solution?  I will assume the former, unless I am told otherwise.  Have you been given the pKa values for each site?  If so, how could you use those values?

 7 
 on: Today at 11:37:14 AM 
Started by Babcock_Hall - Last post by wildfyr
I know it's deviating off paper, but have you considered copper sulfate extraction to remove pyridine? Or maybe add a little water to help that recrystallization.

 8 
 on: Today at 10:52:34 AM 
Started by froggarana - Last post by Enthalpy
That story about expansion between bottles is typical from thermo books. Very much disconnected from reality.

They use to assume some sort of "equilibrium" at the end, but if you make the experiment you won't get any equilibrium between the bottles. The bottles get rather the temperature of the surroundings. Letting heat flow only between the bottles would be badly difficult.

And yes, the gas in A pushes on the gas that has already reached B, so in A it gets colder and in B hotter. In addition, the gas gets much speed that converts to heat in B. At one employer, we autoignited electronic equipment when 300bar nitrogen compressed air in a container. The equipment burned.

What thermo books would like to imagine is that, after "some" time, the heat in B flows to A so they reach an "equilibrium" - but perfect isolation from the surroundings please.

 9 
 on: Today at 10:46:35 AM 
Started by O Cabra - Last post by O Cabra
All i can see is an E operation and possibly a C2 but i'm not sure

 10 
 on: Today at 10:44:52 AM 
Started by rj729 - Last post by sjb
What are the relevant pKas - I don't think the -CHO is that acidic?

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