Science Buddies: "Ask an Expert"

Hello

I am doing the water to fuel to water (here's the link:https://www.sciencebuddies.org/science- ... ll#summary) project for my science fair and was wondering if a carbonate-bicarbonate buffer or a sodium-bicarbonate buffer would work instead of the phosphate buffer. I asked my high school chemistry teacher, but she didn't have the materials required for the phosphate buffer solution and recommended to look into these alternatives. I was also wondering if these alternative buffer solutions would have to be at a pH of 7 for the experiment and if cobalt, manganese, and iron would still form on the electrodes.

In case the sodium bicarbonate and carbonate-bicarbonate buffers won't work, do you have any suggestions of places that have phosphate buffers.

Also, I couldn't obtain the nickel electrodes in time so I am using old Canadian nickels from 1965-1981 because they have a 99.9% concentration of nickel. Would these still work?

Please reply as soon as possible. Thank you in advance for the help.

Hello NEEDHELP123987,

You need to use the phosphate buffer specified in the project procedure. Please see the FAQ for this project for more information:

https://www.sciencebuddies.org/science- ... -cell#help

The buffer materials can be purchased from Amazon. Links are provided in the materials section of the project.

The Canadian nickels may work as electrodes. You might need to sand or grind the fronts and backs of the coins to get smooth surfaces.

I hope this helps. Please ask again if you have more questions.

A. Norman

Thank you A. Norman for replying to my previous question,

However, I have another question for you or any other experts,

The links to the phosphate buffer ingredients are either sold out or it doesn't ship internationally. However, my school's chemistry teacher did manage to find small amounts of the ingredients. Will it be possible to do the experiment with only 100mL of phosphate buffer rather than 250mL.

I would appreciate it if you can reply as soon as possible.

Hi NEEDHELP123987,

The procedure calls for 500 mL of the phosphate buffer. I think the large volume is specified to permit multiple trials. Perhaps you could find a local source for phosphate buffer ingredients.

You might get by with 100 mL of buffer solution if you use a smaller beaker and electrodes.

I hope this helps. Please ask again if you have more questions.

A. Norman

Thank you so much for responding so quickly, norman40.

My school has a variety of beakers so I should be able to find a smaller beaker. I am also using small electrodes (old Canadian nickels) so I think it should be fine.

Thank you so much. I appreciate the help.

Also, can I use cobalt chloride instead of cobalt nitrate for the right reaction too take place.

Hi NEEDHELP123987,

Sorry, but I don't know if cobalt chloride will work in this reaction. My suggestion is to use the cobalt nitrate as specified in the project procedure.

I hope this helps. Please ask again if you have more questions.

A. Norman

I have completed my experiment and it was a success. As I predicted, the cobalt catalyst worked best. I would like to know what about cobalt makes it such a good catalyst for "water splitting" compared to manganese or iron.

Hi NEEDHELP123987,

One of the articles from the project bibliography provides an explanation about how the cobalt/phosphate system might work:

http://ibd.uchicago.edu/undergrad_progr ... Brozek.pdf

Evidently cobalt forms a stable complex with phosphate on the nickel electrode surface. The complex facilitates electron transfer during the water splitting reaction. Different types of cobalt/phosphate complexes can be more effective as described here:

https://www.nature.com/articles/ncomms9253

I hope this helps. Please ask again if you have more questions.

A. Norman