Sciencemadness Discussion Board


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not_important - 11-12-2007 at 21:41

Originally posted by MagicJigPipe
So, what about a tanning bed light since they are specifically designed to emit light in those wavelengths? And you wouldn't have to modify the bulb.

Mercury vapour light - 175W, arc about 5 cm in length, cost for fixture and lamp about $40 US.

Tanning bed lamp - 100 W, 175 cm in length, cost $14 US, needs fixture.

It's going to be easy to get most of the light from that no more than finger length arc onto the apparatus. But a 175 cm long tube ... can you draw me a picture of your setup?

You want the clear mercury vapour lamps, not the white phosphor coated ones.

As for the reflector, consider covering on side of a sheet of light cardboard or artboard with aluminium foil. It doesn't need to be an image quality mirror.

MagicJigPipe - 12-12-2007 at 00:39

Oh, I have some shorter (~2ft) tanning bulbs with the special fixture they came in. I got them from an old sit-down tanning bed in a gym I used to work at. I suppose because of the size issues that the mercury vapor lamp would be better. I just am still uneasy about 100w being able to work well. I won't know 'til I try. I'll do a small scale setup with the equipment I already have and if it's too cumbersome then I'll opt for the Hg vapor.

Sorry for the "archaic" measurements. 2ft = 60.96cm

[Edited on 12-12-2007 by MagicJigPipe]

[Edited on 12-12-2007 by MagicJigPipe]


Reno.456 - 24-12-2007 at 04:52

I may have miss the point but you can heat up salt (NaCl) then run a current through it:

2 NaCl---->2 Na + Cl2

So just collect the chlorine and chuck the Sodium in someone elses pond!

chloric1 - 24-12-2007 at 07:12


Good luck to you Reno!:o:D

First you need a hellafied gas burner to heat the sodium chloride to 801 Celsius so it will melt. Next you will have a nice engineering feat of trying to keep the very hot reactive chlorine gas and molten sodium from exploding in your face:o:o

Klute - 24-12-2007 at 10:08

Adding CaCl2 will diminish the mp of the eutetic mixture IIRC, and Ca metal cannot be produced with iron electrodes. Such an electrolysis should be conducted with a flow of inert atmospher to protect the melted Na, which would seperate as a top layer, while it is transfered out of the cell and cooled away from atmospher. This is done in the industry, and apparently gives Na of good purity. Adapting this to a home lab is completly another story though. I guess it could be done by investing money and time. There should be some fairly detailed patents around.

franklyn - 29-6-2008 at 06:30

OTC pool chorinating compounds and data


a1dirkscience - 29-12-2008 at 18:44

Back to the topic of generating cl2 gas on a long term basis and having it clean and dry.
This is how i built my generator. a five gallon bucket, 4 anodes, 2 cathodes, equal in total mass. The electrodes are carbon/graphite. 4 small water drinking bottles, some 1/4" drip tubing and connectors. some liquid plastic to seal everything up. hot glue duct tape and zip ties to put it all together.
so 4 cl2 collectors and the hyrodgen was left to float away. filled the bucket with distilled H2O and NaCl. Ran the cl2 line in to H2so4.
power supply is a 12 volt dc battery charger set on the start cycle.
after about an hour the cl2 gas comes up to pressure and flows like crazy !!!!!!
as long as there is more Cl than O it puts out cl2 gas , just add a little more NaCl now and then.
Ran it for 15 hours and is still blowing green gas.

heres my question , how can I remove any Oxygen that might be in the gas ? Some on in the thread said it was 0.01 % .
In my books they say that O will only start coming out after the Cl is below the O ???
Im trying to make chloral for Melzers reagent.
And I did make some but no where near enough.
I'm thinking that the Oxygen stoped the chains from forming ?

a1dirkscience - 29-12-2008 at 18:45

P.S. you can get the electrodes at any welding store . as for carbon arc cutting rods. The copper plating peals off very easy and then you have 12" electrodes any diameter you want

Chlorine free radical halogenation light source

slinky - 23-11-2010 at 13:44

Quote: Originally posted by not_important  
Originally posted by MagicJigPipe
I guess my whole point is. Why is Hg vapor so great and why should I spend the extra time and effort to get one?

Because as I said earlier, Chlorine radical reactions are triggered by light in the 300 to 380 nm range, with some effectiveness on up to 430 nm or so. The phosphors in a fluorescent lamp convert most of the UV to wavelengths longer than 550 nm

mercury spectrum

Why not use a blacklight? It gives off the appropriate wavelength of light "320 and 400 nanometres with a peak at 365 nanometres" The party lights are supposed to block all of the sunburn causing UVB and UVC light. It also blocks all irrelevant light between 400-700 nm." Only UVA is given off. It doesn't get hot to the touch either.

I was able to purchase one for 10 USD with a ballast. It's 60.96 cm ( 24 inches ) long. It's light weight and I can easily clamp it vertically to a stand. This will make it easy to expose refluxing liquids mixed with chlorine gas to UVA light. As an added benefit all of the refluxing liquid and chlorine gas should glow like a glow stick :D

^ Fluorescent Black Light spectrum with peaks labelled

"Black light fluorescent tubes are typically made in the same way as normal fluorescent lights except that only one phosphor is used and the normally clear glass envelope of the bulb may be replaced by a deep-bluish-purple glass called Wood's glass. Wood's glass is a nickel-oxide–doped glass, which blocks out almost all of the visible light, that is, energy in the electromagnetic spectrum with a wavelength of between about 400 and 700 nanometers."

"Wood's glass is special barium-sodium-silicate glass incorporating about 9% nickel oxide. It is a very deep violet-blue glass, opaque to all visible light rays except longest red and shortest violet. It is quite transparent in the violet/ultraviolet in a band between 320 and 400 nanometres with a peak at 365 nanometres, and a fairly broad range of infrared and the longest, least visible red wavelengths."

"A tube black light is a basically a fluorescent lamp with a different sort of phosphor coating. This coating absorbs harmful shortwave UV-B and UV-C light and emits UV-A light (in the same basic way the phosphor in a fluorescent lamp absorbs UV light and emits visible light). The "black" glass tube itself blocks most visible light, so in the end only benign long-wave UV-A light, along with some blue and violet visible light, passes through. "

[Edited on 11.23.2010 by slinky]

[Edited on 11.23.2010 by slinky]

slinky - 12-1-2011 at 17:34

I attempted free radical chlorination of toluene as per lien1's post here:

Instead of using a mercury vapour lamp I used a blacklight. As you can see from my previous post, I was quite confident that the blacklight would work because although the light is less intense it is indeed within the specified light spectrum. Post chloronation a fractional distillation was commenced with an insulated snyder column at atmospheric pressure. After the toluene finished coming over the thermometer climbed up to about 163 and there it sat until the temperature climbed to about 190. At around 190 some high boilers started condensing which were a blue/violet colour. My experiment failed to produce products which are consistent with free radical chloronation conditions. Per Organic Chemisrty 2nd edition by Morrison and Boyd p. 386 the products synthesised are consistent with chloronation in the dark.

[Edited on 1.13.2011 by slinky]

Panache - 12-1-2011 at 19:42

That sucks, what a waste of time for you, i think the light intensity from black light is fairly pathetic, also borosilicate will absorb around half your UV leaving you with not much happening. Buy a merc vapour globe and ballast, 250-400 watt is good. If it has a white phospour as most do you need to simply remove the outer glass shell with a careful scratch and tap then run the bulb with the outer shell. removed, it generates lots of ozone and will sun burn you within minures so have yourself protected from this. Get the globe as close as possible to your condenser, remembering this reaction occurs in the vapour phase. If you do not notice the bp going up significantly during the process something is wrong

slinky - 13-1-2011 at 02:40

Thanks panache, I have a large ballast on the way. It should be arriving within a few days. I'd have to agree, the intensity of the blacklight was very weak compaired to a mercury vapour bulb. I thought that allthough less light was given off the fact that all of the light given off was within the desired spectrum would be make the blacklight sufficently powerful and a safer higher efficency route. I was incorrect.

Thanks for the tips regarding the bulb. I'll likely use a transparent bulb. I'm thinking about cutting a hole in an extra large stainless steel mixing bowl so I can mount the bulb to the center of it. The mixing bowl will serve a dual role acting as a light shield for me and acting in the same manner as a parabolic dish. By adjusing the location of the bowl I will be able to concentrate the bulk of the light/heat energy to a small focused area within the refluxing toluene.

peach - 13-1-2011 at 03:31

Don't know if it's been mentioned, expect it has, but there are chlorine generators available that run on salt water and electricity.

A membrane separating the electrodes prevents the chlorine from recombining with the electrolyte.

This member is either a.) asbestos b.) perflurosulfonic acid polymer (PFSA).

Given the issues with asbestos, might be best to avoid that. If someone could find a surplus sheet of PFSA, maybe we could chop it up and split it between those interested.

You may even be able to buy it from the guys who produce chlorine generators for pools, as a replacement part.

peach - 13-1-2011 at 03:55

Quote: Originally posted by Magpie  

I can't envision working with Cl2 without a hood.
[Edited on by Magpie]

Bubble it through 10% NaOH, this is what's done industrially and it doesn't involve it getting airborne and then recaptured.

You may have more luck with the CCl3 / CCl4 if the reaction is warmed - perhaps in a vapour phase - as it takes more and more effort to add the chlorines as you go up (although I seem to remember, perhaps incorrectly, that the final chlorine is easier than the third).

We did some theory about this precise series in A-Level chemistry, and the teacher mentioned that he used to knock up some chloroform when kids brought injured pigeons in from the playground, to humanely euthanise them if they were in a bad way.

Take care using free radical methods, the results can occur at an eye popping rate when the light goes on. :P

[Edited on 13-1-2011 by peach]

Arthur Dent - 13-1-2011 at 04:49

Quote: Originally posted by slinky  
I'm thinking about cutting a hole in an extra large stainless steel mixing bowl so I can mount the bulb to the center of it.(...)

I would suggest that you look into a reflector made of aluminium. I've noticed that most if not all UV reflectors i've seen are made of aluminium. Perhaps stainless steel, although highly reflective, might absorb some of the UV spectrum(?).

An aluminium bowl/cone/reflector would probably be lighter and easier to work, cut and secure to a frame anyway. :)


peach - 13-1-2011 at 05:10

They may be using aluminium due to the significantly lower cost of buying, pressing and folding it. Damn cheap skates! :D

Aluminium reflectors around hot lights tend to end up dull with oxide I've found.

Whilst fixing the bathroom up over christmas, I managed to break THREE lights trying to work with the light ring off.

Should have got myself one of those 400W Halide Wobblelights, those things look absolutely perfect!

[Edited on 13-1-2011 by peach]

Hg vapour lights

The WiZard is In - 13-1-2011 at 08:44

Sorry if this is not new, however, I am not going to read trough
pages of info.

I am not sure this will still work as I believe they may have changed
the design to stop this.

With the older Hg vapour lights you could remove the outer glass
bulb exposing the quartz tube - allowing shorter wave lengths
that were absorbed by the glass bulb out. [Remember not to touch
the quartz with your bare fingers!]

Or you could buy one of those old Hg vapour tanning lights
on eBay. Please don't fry la eyeballs. Love the smell of the
ozone they produce. Or as me coworker Screaming Carl used to
say years ago. I can smell the ozone. - I was using the Zerox

Say anyone remember the old wet copiers? You had to hand
the copies out to dry. And the Termolfax copiers? They used heat and made slimy copies.

"The Thermofax process was temperamental. The coated paper
tended to curl, and being heat-sensitive, copies were not archival.
[5] The darkness setting was tricky to adjust, and drifted as the
machine warmed up. Copy darkness often varied across a page,
some portions of the text being too light and others too dark. Since
the heat absorption of ink does not necessarily correlate with its
visible appearance, there were occasional idiosyncrasies; some
inks that looked nearly black to the eye might not copy at all, and
an exposure setting that worked well for some originals might
require a change to make usable copies with another."


Don't worry about loosing
you mind. When you do you
will never notice.

Screaming Carl

slinky - 13-1-2011 at 12:53

Quote: Originally posted by peach  
Quote: Originally posted by Magpie  

I can't envision working with Cl2 without a hood.
[Edited on by Magpie]

Bubble it through 10% NaOH, this is what's done industrially and it doesn't involve it getting airborne and then recaptured.

[Edited on 13-1-2011 by peach]

Working with chlorine outside of a hood is fine so long as you respect the chlorine and HCl and capture it correctly.

When I first started chloronating the toluene I had a thin glass tube bubbling the offgassing HCl through a 10% NaOH solution. A lot of the HCl was not reacting with the NaOH and escaping with this method. I remembered that Lambda-Eyde used an inverted glass funnel to capture bromine fumes in the bromine thread.

I promptly switched to the inverted glass funnel and placed a heavy flask weight around the neck to keep the funnel submerged in a deep NaOH solution. This worked great. The sunken weighted funnel causes the HCl to have to push down hard on the surface of the NaOH in an effort to escape. I adjusted the chlorine generator drip rate (about 2 drops per second ) to the rate that the solution could accept the offgassing HCl. There is no bubbling at all in the scrubber once the atmosphere within the glassware becomes saturated with HCl. This works much better than a tube bubbling imo. I just checked the PH from time to time and added more NaOH as needed.

[Edited on 1.14.2011 by slinky]

peach - 14-1-2011 at 03:56

Yep, you need to bubble at a rate that is applicable to the scrubber - in the same way that distilling something as fast as possible is likely not doing the results any favours.

If you want to get really fancy, stick some indicating solution in the scrubber for a colourful, visual feedback on what's happening.

It's not only important in terms of capturing the gas at the outlet, getting gases to dissolve or react with what you're primarily trying to do can be difficult because they need to absorb. For example, you're trying to make hydrochloric acid by bubbling HCl. Two people do the same thing with the same amounts of material, one runs it as slow as possible, the other doesn't care. In the latter example, they're probably going to end up loosing a fair amount of it as it bubbles out before it gets a chance to fully dissolve.

[Edited on 14-1-2011 by peach]

slinky - 10-3-2011 at 14:10

Quote: Originally posted by Arthur Dent  

I would suggest that you look into a reflector made of aluminium. I've noticed that most if not all UV reflectors i've seen are made of aluminium. Perhaps stainless steel, although highly reflective, might absorb some of the UV spectrum(?).

I had the same opinion as peach. That manufacturers were just cheap skates. They don't make 'em like they used to. I was also concerned about the aluminium corroding. Well I did some digging around on some aquarium forums and it turns out that I was again wrong.


Specular Reflection

At the other extreme is mirror or specular reflection exhibited by shiny metal surfaces such as chrome, silver or pure aluminium.

It is most important to realise that although specular reflections produce a clear image in the surface of the material, the actual amount of light reflected may be deceptively low.

A matt white painted surface, for instance, has a reflectance of 85% to 90% compared with only 60% specular reflectance from a polished stainless steel surface, while polished aluminium will be approximately 85%.



Aluminium is indeed a superior reflector to stainless steel. These aquarium guys take reflectors seriously because their lights are running so often that they can't afford to lose a few % of reflectance.

Here's a breakdown of what surface textures and finishes reflect well or not and their prices.

In the end I decided to go with a matt white painted surface. It should protect the metal from corrosion the best and can be reapplied. If were to use aluminium it would likely corrode and destroy the high polish eliminating the reflector's efficiency. Matt white's performance is comparable to aluminium and is much better than stainless steel.

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