Sciencemadness Discussion Board

Lab equipment

gatosgr - 31-10-2018 at 21:49

Hey guys, I started this thread for us to post any lab equipment for a diy chemistry lab.

I've found this heater stirrer https://www.ebay.com/itm/85-2A-Magnetic-Stirrer-Temperature-... do you think it's good? I don't know if the thermometer probe is glass coated, if it's not it's trash since temperature control won't work without it.

[Edited on 1-11-2018 by gatosgr]

CobaltChloride - 31-10-2018 at 22:57

It is way too weak at 300W. You're much better of buying second hand good hotplates stirrers from brand such as Corning, Fisher scientific, Thermolyne etc.

Sulaiman - 1-11-2018 at 02:56

I have no idea how reliable the hotplate-stirrer that you pointed to is,
but it is popular so you can assume that parts will be available for a while.


/ waffle on __________________________________________________________

'which car (automobile) is best' ? ... 'horses for courses'.

I think that no matter what heating facilities we have,
a cheap generic hotplate is always useful,
so I suggest that you start with one.
After a while you will know exactly what you want.
(and after another while you will want something else again).
If you are already at this stage then;

I can imagine someone needing only that hotplate-stirrer for many years,
and others getting quickly frustrated.

For boiling water in a beaker to reduce volume or increase concentration,
or in a flask for for a distillation,
due to general heat losses, very roughly,
evaporated water ml/hour = Watts rating of heater.
e.g. a 300W hotplate would boil water off at 300 ml/hour ... roughly.
(Theoretically 300/2257 = 0.133 g/s. ... 478.5 ml/hour)

If jointed glassware is going to be used then I consider 300W to be
too much for 10/19 and too little for 24/29.

It depends upon what type of chemistry you want to do, and at what scale, and cost.

__________________________________________________________/ waffle off

[Edited on 1-11-2018 by Sulaiman]

gatosgr - 1-11-2018 at 12:24

Quote: Originally posted by Sulaiman  
I have no idea how reliable the hotplate-stirrer that you pointed to is,
but it is popular so you can assume that parts will be available for a while.


/ waffle on __________________________________________________________

'which car (automobile) is best' ? ... 'horses for courses'.

I think that no matter what heating facilities we have,
a cheap generic hotplate is always useful,
so I suggest that you start with one.
After a while you will know exactly what you want.
(and after another while you will want something else again).
If you are already at this stage then;

I can imagine someone needing only that hotplate-stirrer for many years,
and others getting quickly frustrated.

For boiling water in a beaker to reduce volume or increase concentration,
or in a flask for for a distillation,
due to general heat losses, very roughly,
evaporated water ml/hour = Watts rating of heater.
e.g. a 300W hotplate would boil water off at 300 ml/hour ... roughly.
(Theoretically 300/2257 = 0.133 g/s. ... 478.5 ml/hour)

If jointed glassware is going to be used then I consider 300W to be
too much for 10/19 and too little for 24/29.

It depends upon what type of chemistry you want to do, and at what scale, and cost.

__________________________________________________________/ waffle off

[Edited on 1-11-2018 by Sulaiman]


Thanks for the info, I haven't found any other heater stirrers in this price range, the good brands's heater stirrers are located in the US and cost double for them to be shipped to Europe where I am at right now. :(

Sulaiman - 1-11-2018 at 13:45

Adding to your confusion, for a similar cost you can get a heating mantle with stirring
e.g. https://www.ebay.co.uk/itm/TOP-220V-Heating-Mantle-with-Magn...

but you would also require a stand and clamp(s)
and at least one flask, or a 'distillation kit'

DavidJR - 1-11-2018 at 14:01

A hotplate stirrer is a bit more versatile than a heating mantle though, so I'd get one of those first.

VSEPR_VOID - 1-11-2018 at 16:03

https://www.ebay.com/itm/500ml-Heating-Mantle-with-Magnetic-...

I want one of these.

gatosgr - 1-11-2018 at 22:08

The mantles are good although I'm searching for s heater stirrer and I'll just use an oil or sand bath for the flask.

gatosgr - 5-11-2018 at 23:11

https://www.ebay.com/itm/SH-3-Hot-Plate-Magnetic-Stirrer-Mix...

[Edited on 6-11-2018 by gatosgr]

j_sum1 - 6-11-2018 at 00:39

Quote: Originally posted by gatosgr  
https://www.ebay.com/itm/SH-3-Hot-Plate-Magnetic-Stirrer-Mix...

[Edited on 6-11-2018 by gatosgr]

Sold Out.
(and does not post to oz. sniff.)

gatosgr - 6-11-2018 at 14:38

Quote: Originally posted by j_sum1  
Quote: Originally posted by gatosgr  
https://www.ebay.com/itm/SH-3-Hot-Plate-Magnetic-Stirrer-Mix...

[Edited on 6-11-2018 by gatosgr]

Sold Out.
(and does not post to oz. sniff.)


found this for you

https://www.ebay.com/itm/Top-Plate-Magnetic-Stirrer-SH-3-Hot...

j_sum1 - 6-11-2018 at 14:56

Quote: Originally posted by gatosgr  
Quote: Originally posted by j_sum1  
Quote: Originally posted by gatosgr  
https://www.ebay.com/itm/SH-3-Hot-Plate-Magnetic-Stirrer-Mix...

[Edited on 6-11-2018 by gatosgr]

Sold Out.
(and does not post to oz. sniff.)


found this for you

https://www.ebay.com/itm/Top-Plate-Magnetic-Stirrer-SH-3-Hot...


Thanks.
Here is my most likely option however: the best I can afford on this list: https://www.ebay.com.au/str/techido

gatosgr - 6-11-2018 at 23:18

Has anyone found a descent scale? Not a microgram scale. 1kg range.


[Edited on 7-11-2018 by gatosgr]

Deathunter88 - 7-11-2018 at 01:59

Anything below 1000W will be pretty useful for boiling liquids/distillation. (IE things you want to be doing with a hotplate)

gatosgr - 10-11-2018 at 00:05

There's this one https://www.ebay.com/itm/SH-3-Hot-Plate-Magnetic-Stirrer-Mix...

Sulaiman - 10-11-2018 at 03:30

Quote: Originally posted by gatosgr  
Has anyone found a descent scale? Not a microgram scale. 1kg range.


[Edited on 7-11-2018 by gatosgr]

I have two cheap eBay small scales, 300g x 0.01g and 2000g x 0.1g
what ever type of digital scales you buy, they will need calibration.
High-end scales often have inbuilt standards,
the three 100g calibration weights for my 300g scales cost slightly more than the scales themselves,
my cheap 2kg scales are effectively useless for 'scientific' purposes as the required calibration weights are too expensive for me.

So, for 1 kg I suggest that you just use commercial or kitchen scales.
(unless you can afford the calibration weight or a regular calibration service)

P.S. As even cheap digital scales are reasonably linear,
and give repeatable performance for a period of time,

If all measurements are in weight, using one linear weighing device
then all relative ratios will be accurate,

This includes stoichiometric starting ratios of reactants, solvent ratios, product yield efficiency etc.
So if you only use one machine for weighing
and everything is measured by weight,
you can calculate results as if the scales were calibrated/accurate.
Using more than one measuring device invalidates the relationships / ratios.

[Edited on 10-11-2018 by Sulaiman]

gatosgr - 19-11-2018 at 23:31

Quote: Originally posted by Sulaiman  
Quote: Originally posted by gatosgr  
Has anyone found a descent scale? Not a microgram scale. 1kg range.


[Edited on 7-11-2018 by gatosgr]

I have two cheap eBay small scales, 300g x 0.01g and 2000g x 0.1g
what ever type of digital scales you buy, they will need calibration.
High-end scales often have inbuilt standards,
the three 100g calibration weights for my 300g scales cost slightly more than the scales themselves,
my cheap 2kg scales are effectively useless for 'scientific' purposes as the required calibration weights are too expensive for me.

So, for 1 kg I suggest that you just use commercial or kitchen scales.
(unless you can afford the calibration weight or a regular calibration service)

P.S. As even cheap digital scales are reasonably linear,
and give repeatable performance for a period of time,

If all measurements are in weight, using one linear weighing device
then all relative ratios will be accurate,

This includes stoichiometric starting ratios of reactants, solvent ratios, product yield efficiency etc.
So if you only use one machine for weighing
and everything is measured by weight,
you can calculate results as if the scales were calibrated/accurate.
Using more than one measuring device invalidates the relationships / ratios.

[Edited on 10-11-2018 by Sulaiman]



edit: thanks but how do you calibrate the scale from ebay, do the scales you've bought have a calibration function?



ok thanks for the info, the weight sensor is not very expensive the most common class is the one with 3000 divisions so for 3kg you have 0.1g accuracy and for 300g 0.01g accuracy, it's not hard to build one with arduino and a HX711 load cell amplifier but it's not worth the trouble for a cheap scale.

this one goes up to 500g but I dont know what class load cell it has
https://www.banggood.com/SF-400C-500g-0_01g-Electronic-Balan...


[Edited on 20-11-2018 by gatosgr]

[Edited on 20-11-2018 by gatosgr]