Sciencemadness Discussion Board

A bit of Bumping

aga - 23-6-2015 at 13:24

Here's a bit of 'Bumping' for anyone who is just starting out.

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Oscilllator - 23-6-2015 at 16:22

Now that looks like a good way to crack a beaker.

smaerd - 25-6-2015 at 07:30

That's some bumping and some hopping :).

Zombie - 25-6-2015 at 17:22

That's why they use boiling chips. ;)

violet sin - 25-6-2015 at 19:19

even better than leaving out the boiling chips,... forgetting to **NOT** put them in at that point!!

been there, done that, on both counts. had stuff bumping soo freaking hard, I was actually amazed the beaker didn't shatter by the time I decided to turn the boat around( cooling down). not a competition, but it was ejecting stuff quite forcefully.

Had a great hand scalding later( after the overt bumping failure), forgot the chips after learning my lesson. sitting right there beside the beaker... had a moment of hesitation,.. and dumped them in late anyway = boil over and steam eruption = burnt hand and running for ice.

years ago, but a guy doesn't forget

Deathunter88 - 25-6-2015 at 22:46

Quote: Originally posted by violet sin  
even better than leaving out the boiling chips,... forgetting to **NOT** put them in at that point!!

been there, done that, on both counts. had stuff bumping soo freaking hard, I was actually amazed the beaker didn't shatter by the time I decided to turn the boat around( cooling down). not a competition, but it was ejecting stuff quite forcefully.

Had a great hand scalding later( after the overt bumping failure), forgot the chips after learning my lesson. sitting right there beside the beaker... had a moment of hesitation,.. and dumped them in late anyway = boil over and steam eruption = burnt hand and running for ice.

years ago, but a guy doesn't forget


That would have been bad, I have had a similar experience while distilling DCM out of paint stripper. The 250ml of paint stripper was in a 3 neck round bottom flask being heated on a water bath. It was distilling nicely and then all of a sudden boiling stopped. I thought my water bath must have dropped in temperature or the solution was not being stirred properly. I drop in a stir bar and WOOSH the mixture comes out of the open neck straight onto my face and the wall. Felt like there were fire ants on my face and the paint on my wall is all gone. At least we know the paint stripper works... :P

Volanschemia - 25-6-2015 at 22:49

Ow, that must have really hurt...
I have not had any accidents regarding superheating/bumping, and hopefully I won't ever, since I have you guys to learn off! :)

violet sin - 26-6-2015 at 00:50

It can be a bit deceptive at times, the second go around proved that to me. After hearing the first diminutive pop of bumping, again(! hanging my head in shame), I turned off the heat and let it sit for a bit( 10 min or so). Kinda wondered why I hadn't dropped the chips in right after the loss of time from the first issue. It was getting kinda late by now, prob 3am.

At this point nothing was screaming that it was too hot to me. IIRC it had couple tiny bubbles here and there that made their way to the surface in a peaceful manner. Not back to back even. The moment of hesitation was a quick "what if" brain check and I decided to roll the dice. Getting tired is not good, adding impatient to that is bad, but I should have been done by then. stopping heat and trying to collect/clean up the ejected material, ate some time.

Also when I said beaker, it was actually a 750ml Erlenmeyer filled less than half way... basically a steam funnel. It happened FAST, like instantaneously. Bottom to top pile of bubbles, then just bubbles around the 3 chips for a bit and a calm solution, then nothing... ( then running for ice)

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couple other points of wisdom, this was long ago when I was first getting back into chem, so might apply to some. I was doing a lot of copper chem, unimportant but it's what was going on at the time.

don't use the wrong thing for the job if you can avoid it. in the past I have done some stupid problem solving because of this.

really limited glassware at the time, trying to reduce H2O content and only had Erlenmeyer's in the larger volume. rigged a small aquarium air pump to a short length of plastic tubing and 5" chunk of 1/4" copper tube. it was bent in a candy cane shape and had synthetic stuffing from a stuffed animal our dogs killed wedged in the bottom end to disperse the air. the hooked end hung from the flasks mouth and blew air into the solution. this eliminated bumping and got the hot vapor out of the flask instead of loitering inside. it also gave a nice mist from all the tiny bubbles popping = no good. plus it helped to oxygenate the solution. the boiling chips alone just weren't effective though...

next idea was to shorten the tubes and give a bend at each end. remove the wad of fluff and flatten the opening that was in the flask. this was to keep the air out of the solution, but blowing across the top of the heated liquid. basically it got the vapor out with out increasing the mist and you could do it hot but at below boiling temp for no solution mist. it helped but.. right tools for the job, there would have been no prob.

next was using boiling stones and to wire some 12V DC computer fans to an old hacked ATX power supply I had, and tape them to various things to move the air in a more efficient manner. that worked, as witnessed by the muggy feeling in the work space. but heat and tape COULD have lead to wires in water. never did, though.

I honestly can't count the number of odd tweaks and work-around's I have had to create and enact because of lack of funding. many were actually decent and functional, some were dangerous or just plain wrong/ineffective/stupid. a good way to learn and-or get hurt. where there is a will there is a way though.

for instance, once while making copper sulfate from the acid and copper by electrolysis for speed, then reducing the sol. with heat and crystallize on cooling. that road gets BUMPY. I ended up taking a couple 12" chunks of 12ga wire and adorned one end with some braided wire and a couple 1cm chunks of 1/8" copper pipe. the other end had a handle made by bending a circle in the wire. you could just set one in a beaker and heat with out worry. the shapes on bottom nucleated vapor well, you didn't have to fish them out as they had a handle and they lasted a LONG time. I still have one around some where, and it was from before I even started reading here, let alone joined.

if you are going to do a work-around for method shortcomings or cut corners because of time, be sure to anticipate the failures that might happen.