Sciencemadness Discussion Board

Photos

madscientist - 24-7-2002 at 19:36

I just got access to a highly-trusted friend's digital camera. I have taken some photos. Here's a link to the index page of the photos:

http://www.sciencemadness.org/pics/index.html

raistlin - 25-7-2002 at 05:43

Ah, we both feel that the flame means happiness....hehe

Raistlin

PHILOU Zrealone - 7-8-2002 at 10:00

Not bad at all!
Anyway here is my five cents contribution:
Phenol is very volatile and can be purified by evaporation condensation in a scealed tube with two compartments (one hot and one cold) (sublimation).It forms long white transparent cristals foul smelling (toxic by the way).

It can be pinkyish due to traces of iron that make a coloured complex with it and also by partial oxydation in quinone.

What you got from acetylsalicylic acid boiling can't be phenol (C6H5-OH) but it must be a twin brother of it that has common properties...salicylic acid (HO2C-C6H4-OH).
It is logical you get this one since: acetylsalicylic acid is an ester of acetic acid and salicylic acid (2 hydroxy benzenoic acid).
CH3-CO-O-C6H4-CO2H + H2O --> CH3-CO2H + HO-C6H4-CO2H.

A simple titration of a known amount will prove this since phenol is a monoacid while salicylic acid is a diacid (you will thus need twice the amount of base to neutralise 1 mole of it than 1 mole of a monoacid like HCl, acetic acid, ....

Trinitrophenol exist under several forms:
1)...-C(-OH)=C(-NO2)-...
is pale yellow and is in resonance with a second form (less stable-more unstable also :o (see 2)).
2)...-C(=O)-CH(-NO2)-... (following enol-ceton hybridation resonance) (this one is deep yellow and is present like 1% and is responsible of the yellow color of TNP and also of its sensitivity).As you see the last form is a nitroaliphatic ceton and thus can display another resonance (see 3) nitroaliphatic-nitronic acid resonance.
3)...-C(=O)-C(=NO-OH)-...(this last one is deep red and much more unstable (this means also more sensitive and powerful)...it turns slowly to the stabler (little more) 1 and 2 forms.

So basically
99% HO-C6H2(NO2)2-NO2
1% O=C6H3(NO2)2-NO2
and the last one can make
various % (depending on the operating conditions) of
O=C6H2(NO2)2=NO-OH

Unstability and power is in the order:
3>2>1.

Hope this helped!

PH Z

madscientist - 24-8-2002 at 15:14

I thought that salicylic acid decarboxylated when strongly heated.

HOC6H4COOH ----> C6H5OH + CO2

Is there something I'm overlooking? :)

PHILOU Zrealone - 8-9-2002 at 09:40

If strongly heated phenol melts and sublimes!
So isolation is a problem without a proper closed cooler condenser (cristalliser).

Nice pictures.

Voltforce - 4-10-2002 at 18:32

It makes me feel good to know that I am not the only 16 year old out there that conducts expirirments without enough regard for safety. One question- did the acid burn hurt that much? I got a tiny sprinkle of 70% nitric acid on my skin and although it did not leave a mark, it continued to feel like a needle was stuck in it for several days.

Nick F - 5-10-2002 at 13:48

Really? That's strange, I've had nitration mixtures on my skin loads of times (I'm clumsy), and it's never hurt. It just gives yellow, peeling skin. Although I've never had it anywhere more sensitive than the fingers, where there is thick skin... maybe this protected me.

HNO3 - 3-1-2005 at 19:09

MadScientist: You have the same type of bottle of KMnO4 and type of gas mask I have.:cool: I so love my gas mask; HF, HCl, Cl2, Br2, I2, NH3, ClO2, organics, 99.97%:o:D of particulates GONE!!!!!!!!!:cool: