Does anyone have a suggestion for heating a mixture of H2SO4 and solids at 200C on an electric hotplate and stirrer? I've been using Pyrex beakers and three have shattered so far.

Get a round bottom for fucks sake man. You don't put the vessel RIGHT on the hot plate. You use an oil or sand bath or something. Sand rocks. Don't use oil for that high temp though. You can't do SHIT with a beaker. Just because it is pyrex doesn't mean it will stand up to the various hotspots created because of it's design. A round bottom allows even heating. Florence will work too.

Thanks Stupid Noob. Will the Florence flask need to go in a sand bath or can it go directly on the hotplate?

Well, you COULD place it on the plate, but I wouldn't want to. Why stress your glass more than you have to? A sand bath is easy to do, and provides MUCH more even heating than just sitting it on the plate. Trust me man, it will save you loads and loads of problems.

There is quite an informative pdf regarding Lab Pyrex to be found, here:

http://www.barloworld-scientific.com/internet/Download.nsf/directdownload/TALN5NVDRJ/$file/Technical%20information_glassware.pdf

(Cut n paste into address bar)

Thanks for that link, worth a reading!

Well... n00b got it... sand bath. ...but since their are n00bz who are not n00b...

...keep in mind that how gently you treat your glass, not the temperature, is what determines if it shatters. Completely untempered glass - jelly jars, christmas ornaments, etc - will have no problems going up to a few hundred centigrade if you're REEEAALLLY careful on slow heating and cooling. Exquisitely tempered glass will shatter like a bitch if you take it from a semimolten heat to quenching in ice immediately.

Sure, chemgeeks tend to like tempered glass 'cause you can put a light flame on it... but it's not how your glass was made as it is how much you abuse it.

http://www.mcgillswarehouse.com/Item...emID=122120026

Alternativly, buy 10-11 of these puppies and and a impromtu furnace/oven of your hot plate. Set it up right you you can heat to aproxamately 200 degC with very little supervision. Turn the hotplate to the low setting , wait and hour measure the temp, bump up the heat, wait another hour, measure again, mark the point on the control knob where you product reaches 200 degC.

Next time you want to repeat the process just put on your beaker, make the impromtu oven, set to the marked point, and leaves it be for a few hours. Then turn the hot plate off, let the beaker cool in the oven for and hour. Come back, starty your next batch. wait a couple hours, repeat.

Would sand baths need to be damped with water or an oil or anything to conduct the heat better? Or does it just work like a bentonite refractory shield?

Use the best oil you can find.