Here's a way to make a home brew magnetic stirrer for doing titrations
in a test tube at next to no cost. Go to a surplus store and look for
small DC motors. Look for ones that are about 30-50 mm in diameter
depending on the size of your test tube. I got some motors with a
plastic cap at the end where the brushes are located for 99 cents
each. Inside the motor housing there are two magnets which are formed
to surround the rotor (or in this case your test tube.) Pull the rotor
out and attach the empty motor casing to the shaft on a second motor.
Now you have a motor rotating a hollow cylindrical magnet. Use a
retort stand to hold the assembly vertically and lower the test tube
into the magnetic field in the empty motor housing. Done!
I also applied a kapton thin film heater ( like these
http://www.omega.com/techref/electric.html ) to the test tube using the
spring from a ball point pen to hold the heater against the test tube.
About 10 watts is all that is needed for heating the oil/alcohol
mixture for titration.
It sure helps to have uniform heat and agitation for doing accurate
titrations.
Cheers
Joe
JJJN wrote:
Hi Brian,
A magnetic mixer is just a small DC motor that is variable speed that
rotates a STRONG magnet under a platform. You then place in the jug PVC
or Polyethylene coated Magnets and screw the lid on. Turn on the mixer
and its like a blender inside. If you do use Red devil lye it can get
reallllllly hot fast but I never melted or expanded to much. I rather
prefer the slower dissolving lye with this type of mixer. I got mine
free as it was replaced with a newer one and was gathering dust. when we
moved our lab my good friend the chemist gave it to me rather than throw
it away. They would be real easy to build and the part that goes in the
Methoxil is cheap at NW Scientific Supply I can give you the email if
you want it.
Jim
Brian Rodgers wrote:
Hi Jim
" I use Lab grade Lye that is in pellets not grains like Red Devil."
Please give us newbies a few possible sources, this is a tease.
"It takes more time to dissolve but I use a magnetic mixer so the
reaction is in an air tight container and can be left for however long
while i do other things.
I will Google "Magnetic mixer" but an explanation from you would be
great too. What is? Where to find? Standard lab equipment? Etc. It
sounds pretty damn cool.
Not sure how to search the archives for a resource list. Kieth, can you help?
Once I get today's mini test batch figured out I will need to begin
the task of relieving my on anxiety over where to find chemicals in my
area.
I spent quite a bit of time with my 87 year old father last night
talking chemistry. He's retired forty years, but I have been copy and
pasting stuff from you all and the journeytoforever web site over to
him since early Summer. Now that I am getting set to do this I have
sent him more scientific data and less youthful emotional fanfare.
Today I make the sodium methoxide.
I better get after it.
Brian Rodgers
Good Luck,
Jim
Rafal Szczesniak wrote:
Hi,
I've recently bought new fresh methyl alcohol and lye. I have measured
out exact amounts, mixed lye with methanol and - a bit of a surprise,
the solution haven't actually got warm. No temperature, fumes,
whatsoever. Is this normal, or could I have done something wrong ?
The chemicals are most probably pure and good quality. Also, lye has
been completely dissolved.
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