Hoffman Voltameters

[Krysia Lee]

Hi
We've used these sucessfully for along time now but when I used them yesterday they didn't seem to work as effectively. Does anyone know if the electrodes in these things eventually perish?
Have a lovely day.
Thanks Krysia

[noona]

Hi
Yes mine did so we ordered new ones.
They are not as good as the old(and I mean old) ones but the do the job.

[Ian]

I don't have my catalogues with me at the moment cos it is my "day off" but I think that I got my new electrodes from Serrata. They were not cheap though. Somewhere around $45 each from memory ( I think??). Make sure that you use enough Sulfuric Acid in the solution. Once upon a time, I used to add a few drops of Conc H₂SO₄. The results tended to be variable. Now days, I forget about the water and just use straight 1M H₂SO₄. I get great results every time.

Just don't do what my Chemistry teacher did. She used 1M HCl instead!!! The green gas she generated was very pretty and the next couple of classes enjoyed having lessons in the playground, but it did smell a bit!

Ian

[smiley]

Can I mention I love my baby "Student Voltameter"! Although one has to set it up the lesson before, or start it at the beginning of a lesson and come back to it, I do like it. It is simple, the electrodes are built in, there are no stupid taps to jam or "freeze". Collecting the gas can be a pain, but it is possible to substitute a test tube for the collection rig and then you have H2 or O2 in a tube, ready for testing. They are a lot more pain free that the old glass units, and ideal for junior years.

[Ocker]

the electrodes are platinium, when they stop working I carefully hold so electrode its flat on bench and stroke carfully away with fine steel wool turn it over and do other side

[sunray18]

I use 2M sulfuric acid - soooo quick!!!

[matchstick]

I have a student voltameter and it is so cute..with the other i recently bought new platnum electordes from haines 2 for $110.
The only prob is the stopper is too small for my voltameter so i carfully pulled out the electrode and had our GA drill holes in stoppers that fitted.....woolah!
Another peice of science equipment repaired by "wonder labbie".......just on my way now to repairmicroscopes