Author Topic: lava lamp question  (Read 2558 times)

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12cheman12

  • Guest
lava lamp question
« on: May 25, 2004, 11:49:00 PM »
swim has this lava lamp, when he removes the main glass bit with the waxes and liquid he is left with a stand that has a globe inside it. Swims flask fits perfecty inside this stand and it sits right on the globe, it brings water inside to a temp of about 102C... perfect he thought. But since he places the glass directly over the globe and doesnt use any oil/sand bath (theres no way of fitting one inside stand) would this be a bad idea because there would be hot spots created right were the globe touches the flask right?

abolt

  • Guest
Personally
« Reply #1 on: May 25, 2004, 11:54:00 PM »
I prefer to set up a series of mirrors and direct sunlight on to my reaction flask.

Make little venetian blinds for the mirrors, that you can open and close, in order to control the heat of your reaction.


Red_Crown

  • Guest
If its just one point of contact
« Reply #2 on: May 26, 2004, 01:31:00 AM »
If its just one point of contact, well, of course there will be A hotspot. (Your flask would be sitting directly on the bulb, yes?) Even if you clean all of the glass very well, it will still be hotter there. Try finding a watchglass that can fit betwixt the bulb and your flask, and set it with the concave side facing up (towards the flask) and fill it with some oil or sand or something)... .. . Use dye. If you could darken your oil with ink or something, more heating would be afforded.

Another guess-possibility would be to wrap the bottom of your flask in aluminum foil. It would distribute the heat effectively. Use a marker and blacken the bottom face for more heating.   My little friend Maroon recently performed a reaction using a 20mL long-neck round-bottom flask covered in blackened aluminum foil and a 200watt light bulb. (Swim calls it the "Micro Desktop Ornament")

12cheman12

  • Guest
yeah i think swim might try a few sheets of...
« Reply #3 on: May 26, 2004, 01:49:00 AM »
yeah i think swim might try a few sheets of aluminum foil. The Globe he has is only 30 watts, but the surface temp of it goes to 200C and it easily heats his flask to boiling.

12cheman12

  • Guest
i just thought of something, would experiment...
« Reply #4 on: May 26, 2004, 05:44:00 AM »
i just thought of something, would experiment myself and find out the answer but is not in the current situation to do so. To boil alky out of water, you just boil it until the temp reaches 100 degress, because the temp of the alky/water mixture cant reach over the boiling point of alky (78C i think) until all the alky is gone right. So if i put water in my flask and set it on a lamp to find out how hot it can go, it will only reach a few degress over 100 right? where really it might be able to heat oil up to 150C.

DrLucifer

  • Guest
Heating.
« Reply #5 on: May 26, 2004, 06:01:00 AM »
Jesus mate, swim cant bear this, you need help!
Get some dosh ($250) and ask swim for an electrothermal heating mantle which caters for 250ml RB flasks.
You know how to make it happen!


weaz1dls

  • Guest
Ok,
« Reply #6 on: May 26, 2004, 10:50:00 AM »
Your lava lamp will work.  HOWEVER, light is known to decompose or degrade HI.  So this is not your best choice for a LWR.  The lamp will reach higher temps as the flask heats up.  If it is not a true flask and an OTC vinigar bottle or such, it increases the risk.  Puting foil inbetween only works with smaller flasks unless care is taken in size and contour to the flask.  The foil can create small pockets of air, like a mini thermous.  Not in your favor here.  If you will be doing a cook in the range of 6 or less hours, then this will do.  Do not use more than the rated wattage of bulb.  ANY MOISTURE CONTACTING A HOT LIGHT WILL CAUSE IT TO BREAK.  The smaller ones are a little more sturdy, but be carefull with the bulb.

Post 450723 (missing)

(weaz1dls: "modifications", Stimulants)

SHORTY

  • Guest
No Light?
« Reply #7 on: May 26, 2004, 03:54:00 PM »
Thats strange cause i find light to be beneficial to the rxn and have a 100w light bulb hanging next to my flask every time i do a lwr.

As far as using the lamp for a heatsource why not just try it as is and see if it works before trying to modify it?  You might want to calibrate your thermometer too cause i doubt that you could get water to get as hot as 102C since it boils at 100C.  Unless you superheated it.  If the lamp don't work you could always use an electric hotplate from a discount store.

Its really not as complicated as this thread makes it seem.


WizardX

  • Guest
photodissociation
« Reply #8 on: May 26, 2004, 08:34:00 PM »

Thats strange cause i find light to be beneficial to the rxn and have a 100w light bulb hanging next to my flask every time i do a lwr.




Shorty: Do an experiment by placing 10mls of 57% HI solution into two separte testtubes. Seal each testtube. Place one in a dark place, and the other irradiated with your 100 watt light globe.

Do not put the second testtube too close to the 100 watt light globe so that it heats the testtube, but rather only irradiates it.

See what? How can photodissociation help the reaction?


kris_1108

  • Guest
At the end of the day
« Reply #9 on: May 27, 2004, 03:45:00 AM »
Ok so lets say somebody uses a bright light bulb as a heat source for their reaction. Lets assume it's a 36hr reflux. What happens to the HI? Does it decompose? Does this been some nasty by-products would bee in the end product? OR does it just mean the product may be unreduced/partly reduced?

Red_Crown

  • Guest
Sidestep
« Reply #10 on: May 27, 2004, 07:58:00 AM »
.. Herein lies the beauty of tightly covering the reaction flask with marker-blackened foil.


Red_Crown

  • Guest
Ghetto metal working
« Reply #11 on: May 27, 2004, 08:36:00 AM »
Aluminum foil is goddamn useful.. Make reflectors that contain the heat and light around the bottom of the flask, and away from the condenser. It can also be used to fashion little L-shaped fins coming off of an air-cooled condenser - just like a CPU cooler. (Use only 1, preferably heavy duty, layer at a time for conduction purposes.)


SHORTY

  • Guest
Don't have any 57% HI to test
« Reply #12 on: May 27, 2004, 08:08:00 PM »
WizardX,
I don't have any 57%HI to test with because i use Hypo to make the HI and therefore i don't think i could get the expected results.  However, my rxns go from yellow to clear or clear with a hint of yellow.  I started using a light a long time ago and have not done much testing on how useful or unuseful it may bee.  I remember reading that the HI/rp/i rxn takes place in the presence of heat and light and for some reason it became a standard part of my setup.

My main point was that light will not cause a rxn to fail at least it hasn't for me.  I am looking for that reference and will post it if i find it.

So, will light harm or effect the rxn in a negative way?