Science Buddies: "Ask an Expert"

Science Buddies' recommended supplier (United Nuclear) is out of stock indefinitely and after many google searches and phone calls we have found that since the 9-11 crisis this is a highly regulated, regarded as hazardous, material that either can only be sold to a business or school or you might be able to buy a much larger quantity than you need at an exorbitant price. Unfortunately, we ordered everything else (along with the cobalt nitrate from an alternate supplier who sent an e-mail voiding the sale with promise of a refund after we thought the" mission was accomplished.") Can you help us to either find another source for cobalt nitrate or a way to do this project without it? We've invested a lot of money already. Thank you.

Hello,

Have you considered asking the school to order it? If you cannot obtain it by any other means, purchasing it through school might be the best option. I also did an Internet search and saw a company called "Chemisphere Limited" in the UK that might ship overseas. I don't think the site specifies if what you are looking for is available to the public, but you could try and email. It's worth a try!

Thank you for your ideas but the science teacher just let us know that wouldn't be possible (liability issue) as we had e-mailed her regarding purchasing through the school before posting to this site. Also, cobalt nitrate seems to be restricted to ground shipping. We are asking everyone we can think of and appreciate any help we can get.

Cobalt nitrate solution is not so hazardous as the dry form and seems to be available at http://www.scientificstrategies.com/pro ... 120ARC.htm.

This is an 8% solution, so you'll have to add enough of it to be equivalent to the dry form used in the project writeup.

Good luck, WW

Thank you so much for your idea! Would 120mL(the size shown in the link you provided) be enough for experimenting and how can we determine how much is comparable to the powder form?

Your last question is hard to answer for two reasons.

First, the amount to add isn't specified very well. It is given by showing a picture of some of the powder on a spatula. I will guess that the amount shown is less than a gram.

Next, the amount in the 120 ml bottle is a little vague: see http://en.wikipedia.org/wiki/Mass_conce ... emistry%29. The best guess seems to be that the bottle contains (8 gm /100 ml) * 120 ml = 9.6 gm.

If my guess and understanding of the 8% concentration is right, you should have enough to form the electrode at least once and maybe a few times. No guarantee.

We had been checking back with United Nuclear (the Science Buddies recommended supplier of cobalt nitrate) ever so often and lo and behold it was back in stock! Hopefully they won't " change their mind" before shipping it to us. Thank you again for your help and hopefully we'll be posting project success in the future.

Please let us know if you succeed in buying the Cobalt Nitrate.

Received Cobalt Nitrate from United Nuclear-plan to work on project during Christmas vacation.

What are some variations of this experiment? I'd like to make my project more interesting.

qca,

Have you made the basic experiment work? How well did it work?

There are many possibilities for additional work. How do other metal nitrates work? How well does the cell hold up to prolonged use or shaking? What might improve its durability? Can you think of other ways to lower the voltage of a hydrogen generator?

Happy experimenting, WW

We did the experiment a few days ago, and it worked out fairly well. The voltage stayed at levels I expected it to for most of the experiment. The only things that seemed odd were that one, we didn't see any or hardly any bubbles, and two, the voltage in the fresh phosphate buffer seemed to actually stay the same as with the leftover cobalt nitrate, and actually started going up. Do you have any ideas as to the cause of these?

qca,

You say, "The voltage stayed at levels I expected it to for most of the experiment. " I'm not sure what you expected.

Did the cell voltage decrease when you added the cobalt nitrate? Did you see the brown film form?

The cell voltage should remain the same after you remove the cobalt nitrate as long as the film that precipitated on the anode stays in place. The cobalt nitrate in solution has little effect other than to change the solution conductivity a little.

I don't know why the voltage increased. Perhaps some of the anode film came off? Do you see any change in the film as the increase occurs? This is a good question to answer by experimenting with different conditions.

I suspect that the quantity of bubbles forming will be small. You might experiment with different currents to see if bubble production is proportional to current as it should be.

I'm happy to hear that you are getting results. WW