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Tungsten.Chromium
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[*] posted on 26-10-2014 at 11:22
Recommendations for a hotplate?


I'm really starting to get into my hobby of chemistry and while studyino it has taught me some cool stuff. I want to try a few things.

I have a few various Pyrex flasks and such, but it looks like a key thing I'm missing is a hot plate/magnetic stirrer. I've been researching around it looks like this is one of the things you want to spend a few bucks on so it lasts(sort of like an electrician's multimeter).

The one I've been looking at is this one: http://www.amazon.com/gp/aw/d/B004DGIC0W?pc_redir=1414184305...

It looks like corning makes the best stuff, and this is one of the best models they have, but the cheapest I've been able to find it anywhere is over 500.00. Is it worth the money to invest in this one or am I better going with a cheaper option. I really like how it has digital readouts of the stir RPM and temperature




Prosit!
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[*] posted on 26-10-2014 at 11:40


You might want to check out ebay. I found this one there:

photo.JPG - 2MB
It's old, but it works great. I got it for only $45 including shipping!




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[*] posted on 26-10-2014 at 14:49


Really consider what you actually need. there will be plenty to spend your money on.
My magnetic stirrer is an old PC fan with two button neodymium magnets stuck onto it with a hot glue gun. Stirrer bars were $7 from China on eBay. I am using a camp stove as a burner. I might bum around some yard sales to see if I can pick up a hot plate of some variety (Ok, the cheap motel variety).
I am obviously going to run into trouble the day I wish to stir and heat at the same time. Then my setup will be a PITA. However, when that day comes I will shell out for one of these or something similar: http://www.ebay.com.au/itm/271274303830?ssPageName=STRK:MEWA...

And as a bonus I will have some stirring and heating gear to allow me to do two things at once.
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aga
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[*] posted on 26-10-2014 at 14:59


Choice of Hotplate/Stirrer basically comes down to two factors:-

1. Vanity
2. Money

The really expensive ones look nice, heat stuff and stir stuff.

The cheap ones look less nice, heat stuff and stir stuff.

The second hand ones look awful (if they ever really got used), heat stuff, and stir stuff.

Home made stuff can look, er, interesting, yet can still heat stuff, and stir stuff.




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[*] posted on 26-10-2014 at 15:00


Ok. I'm interesting.
:)
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[*] posted on 26-10-2014 at 15:14


Quote: Originally posted by aga  
Choice of Hotplate/Stirrer basically comes down to two factors:-

1. Vanity
2. Money

The really expensive ones look nice, heat stuff and stir stuff.

The cheap ones look less nice, heat stuff and stir stuff.

The second hand ones look awful (if they ever really got used), heat stuff, and stir stuff.

Home made stuff can look, er, interesting, yet can still heat stuff, and stir stuff.


Well said.
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DrMario
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[*] posted on 26-10-2014 at 15:41


Quote: Originally posted by Tungsten.Chromium  
I'm really starting to get into my hobby of chemistry and while studyino it has taught me some cool stuff. I want to try a few things.

I have a few various Pyrex flasks and such, but it looks like a key thing I'm missing is a hot plate/magnetic stirrer. I've been researching around it looks like this is one of the things you want to spend a few bucks on so it lasts(sort of like an electrician's multimeter).

The one I've been looking at is this one: http://www.amazon.com/gp/aw/d/B004DGIC0W?pc_redir=1414184305...

It looks like corning makes the best stuff, and this is one of the best models they have, but the cheapest I've been able to find it anywhere is over 500.00. Is it worth the money to invest in this one or am I better going with a cheaper option. I really like how it has digital readouts of the stir RPM and temperature


That is, indeed, one of the best hotplates under US$1000. It's the kind my research institute would buy, because
- it uses PWD to adjust the hotplate temperature, which allows it to quickly reach the desired temperature, with little overshoot (cheaper hotplates use a simple on/off system). This is combined with a CPU-controlled algorithm, again, to attain the target temperature quickly and with low overshoot.
- it allows for accurate temperature adjustment with very low bias.
- very durable ceramic plate surface. You start to appreciate this when your hotplate is as heavily used as ours.
- option to add external temperature sensor (or, as Corning calls them, "external controller").
- uniform temperature distribution across the plate. You will appreciate this... quite rarely, I guess, if all you need to do is heat a beaker. If you need to process wafers or other flat samples (with films), you will want this feature - but to be honest, you'd need a larger hotplate.

How important are the features listed above? For an amateur, probably not too much. I am an amateur too (in addition to my day job), and I know I wouldn't invest in such a hotplate. Not unless I become unexpectedly rich, which isn't going to happen as I don't play the lottery.

Finally, that Corning hotplate will only fully shine if you also buy this:
http://www.amazon.com/Corning-External-Temperature-Controlle...
- that is, the external thermal sensor that allows you to adjust the temperature of the liquid you're heating, rather than just adjust the temperature of the plate on which you are heating. These Corning thermal sensors are quite expensive, and adding it all together, you'll have to pay US$ 900.

Too much, IMHO, for an amateur.

Instead, look for the cheaper Chinese hotplates that go for about US$100 including shipping. Everything on those models is worse than with the Corning hotplate, but you still can stir and heat, and have a reasonable control over the temperature.

[Edited on 26-10-2014 by DrMario]
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DrMario
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[*] posted on 26-10-2014 at 15:46


Quote: Originally posted by aga  
Choice of Hotplate/Stirrer basically comes down to two factors:-

1. Vanity
2. Money



Not at all true. The expensive hotplates definitely have their place. Not in an amateur lab perhaps, but their raison d'etre has nothing to do with "vanity".
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[*] posted on 26-10-2014 at 16:13


The hotplate above is not good. It may be cheap but it's too old and unreliable and cosmetically very ugly - haha. The best hotplate/stirrer combo is manufactured by Corning. Any one of the following model will be an excellent addition to any home lab: PC-351, PC-320 or PC-420. I personally prefer the PC-420 model. They will cost about 150.00 on ebay, used. I used my hotplate stirrer quite a bit so I rather make some investment. Good luck.
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[*] posted on 26-10-2014 at 16:20


I guess I'm near about the same place. It's probably a newbie thing, scouring Ebay looking for gear. I've had quite an education on glassware..still wondering how one decides on a joint size standard...

I did the the same thing you've done when it came to a hot plate/stirrer... Initially I bought a $20 hot plate at Walmart. It worked but I wanted some indication of temperature..
I looked all over ebay, tons of choices from top to bottom. Ended up buying the 10 x 10 Corning digital with probe at Amazon...

Mainly because I wanted digital, the corning looked like a solid unit, and it is.
Looking for a centrifuge now, will probably get that used..


Edited to add;
So far the most startling thing cost wise, has been books..

[Edited on 27-10-2014 by NOV:5]

[Edited on 27-10-2014 by NOV:5]




Remember, Remember...
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[*] posted on 26-10-2014 at 16:50


Quote: Originally posted by jamit  
The hotplate above is not good. It may be cheap but it's too old and unreliable and cosmetically very ugly - haha. The best hotplate/stirrer combo is manufactured by Corning. Any one of the following model will be an excellent addition to any home lab: PC-351, PC-320 or PC-420. I personally prefer the PC-420 model. They will cost about 150.00 on ebay, used. I used my hotplate stirrer quite a bit so I rather make some investment. Good luck.
If you're referring to the hotplate that I have, I've tested it, and it works great. It's got a durable ceramic plate and the whole thing is built like a ton of bricks. My theory is that if it's continued working well for the past 40 years it's not going to give out any time soon!



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Dr.Bob
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[*] posted on 26-10-2014 at 17:16


I have a few more older used Corning stirring hotplates that I am currently checking, cleaning, and testing. I have sold most of these used ones for $100 plus shipping, which is about $20. A few need new cords, which is what I am working on now. It turns out that DCM, DMSO, DMF, and many other solvents are rough on the cords and soften the plastic a lot. :-( But I have lots of replacement cords from other items.

I have a few used ones, mostly 351 type or other older ones. Most are a little stained or dirty, but I have been using the same models for years in the lab at work, some of those are 20+ years old, and still work well. If people are interested, let me know and I can make a waiting list. Once I get some ready, I will go by the people who were first to ask. I also have one or two stirring only plates, maybe also one hot plate only (no stirring). The stir plates are great for use with heating mantles and are a little cheaper
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[*] posted on 26-10-2014 at 17:26


Thanks Dr Bob. I think I know the answer to this, but how much would it cost to ship to Australia?
If the total cost could be kept below $150 I might be interested in one of these.
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[*] posted on 26-10-2014 at 18:10


Dr.Bob, in which country are you and your Corning hotplates? USA? In that case j_sum1 may not be able to use them. And neither could I :(
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[*] posted on 26-10-2014 at 18:13


Quote: Originally posted by zts16  
You might want to check out ebay. I found this one there:


It's old, but it works great. I got it for only $45 including shipping!


My greatest issue with that hotplate is that I have no knowledge of the plate's temperature, and no way to adjust said temperature.
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[*] posted on 26-10-2014 at 19:04


Quote: Originally posted by DrMario  
Quote: Originally posted by zts16  
You might want to check out ebay. I found this one there:


It's old, but it works great. I got it for only $45 including shipping!


My greatest issue with that hotplate is that I have no knowledge of the plate's temperature, and no way to adjust said temperature.
Yes, unfortunately the plastic dial that shows what temperature it's at is missing.



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DrMario
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[*] posted on 26-10-2014 at 22:35


Quote: Originally posted by zts16  
Quote: Originally posted by DrMario  
Quote: Originally posted by zts16  
You might want to check out ebay. I found this one there:


It's old, but it works great. I got it for only $45 including shipping!


My greatest issue with that hotplate is that I have no knowledge of the plate's temperature, and no way to adjust said temperature.
Yes, unfortunately the plastic dial that shows what temperature it's at is missing.

And even if it were there it would be too imprecise to indicate anything meaningful.

Really, that's my only (but pretty fundamental) gripe with your hotplate. Otherwise, it's quite solid.
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[*] posted on 26-10-2014 at 22:54


Like I said before, consider what you actually need.
If you actually need precise control over the exact temperature you are providing then you will need something flash. Me, the most I am likely to need to do is put a thermometer in my flask to find out what is going on. Too hot and I turn it down. Too cold and I turn it up. i suspect this is typical of most hobby chemists.
To answer the original question, you don't need the fancy schmancy hotplate. Spend your money on something else until you do need it. By then you will have the experience and knowledge to know exactly what your requirements are. (Buying something more than what you need could amount to vanity. Or a misplaced sense of convenience. Or having too much money. Or something else. But whatever it is, for a beginner it is not chemistry related.)
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[*] posted on 27-10-2014 at 00:08


temp stability is important if you are refluxing or distilling. and variable stirrer speed I found very important as well.
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[*] posted on 27-10-2014 at 01:46


Is the hotplate strong enough? I have found that weaker, less than 500 watt plates are pretty toyish on doing anything unless you do 50ml volumes and have 8 hours time to distill them. Plus if you gonna do vacuum distillations you will need magnetic stirring or it will puke all up.

Just for you to know the chinese bante plate is horrible. It takes half an hour to heat 50ml of water to boil and the stirrer is so unbalanced it will vibrate the contents off the plate in no time.

[Edited on 27-10-2014 by Dr.Arz]
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[*] posted on 27-10-2014 at 02:21


Quote: Originally posted by Dr.Arz  
Just for you to know the chinese bante plate is horrible. It takes half an hour to heat 50ml of water to boil and the stirrer is so unbalanced it will vibrate the contents off the plate in no time

Thanks for the heads up. On closer inspection I see that it is only 150 watts. When I get around to buying something I will get one with more oomph.
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[*] posted on 27-10-2014 at 02:56


Quote: Originally posted by Dr.Arz  

Just for you to know the chinese bante plate is horrible. It takes half an hour to heat 50ml of water to boil and the stirrer is so unbalanced it will vibrate the contents off the plate in no time.

[Edited on 27-10-2014 by Dr.Arz]


Which ones are these "bante" hot plates? If you can link to a photo of one, that would help me a great deal.
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[*] posted on 27-10-2014 at 03:39


I think the one I linked to up thread.
http://www.sciencemadness.org/talk/viewthread.php?tid=41282&...
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[*] posted on 27-10-2014 at 04:33


I am in the US, so these are 110 V, not helpful in most other countries. But there are other used ones on Ebay and other sites which come up, some are reasonably priced. Corning makes 220 versions, so that would be fine for most other countries.
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[*] posted on 27-10-2014 at 04:44


Not really: the only "reasonably" priced Corning hotplates are from US eBay sellers. The rest, which is very little, is unreasonably priced.

I just spent the better part of a quarter of an hour trying to find any non-US Corning hotplate on eBay. I came up with nothing.
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