Science Buddies: "Ask an Expert"

Hi! My kindergartner and I did an water electrolysis for science fair project. We have two questions - 1)any ideas for a catchy title?
2) we followed the protocol on this website, http://www.navigatingbyjoy.com/2014/09/ ... ctrolysis/, and used baking soda instead of salt as the electrolyte in the water. Based on what we had read about using salt, we had expected precipitate to be made and decided to avoid this by using the baking soda. We were quite surprised that when we set up our experiment, we easily made loads of H2 at the first electrode but the other electrode made hardly any gas(not the 1:2 ratio you would expect) but made loads of rust colored precipitate. Any ideas on what we could change? or what the precipitate is?
THANKS SO MUCH!

Hi! Sounds like a fun project! In response to your first question, I might suggest "A Current through the Current: The Electrolysis of Water" or "Time to Split Up: The Electrolysis of Water."

In response to your second question, H2 is made at the first electrode (the cathode) because its reduction potential is higher than that of sodium, i.e. the H+ in water gains electrons more easily than the Na+ ions (sodium bicarbonate dissociates in water to form Na+ and HCO3- ions). While I'm not sure what the precipitate at your anode is, it's possible that the HCO3- ions have a higher oxidation potential (lose electrons more easily) than the O(2-) ions in water, so HCO3- is oxidized at the anode rather than the O(2-) ions. I'm not sure why your results deviate from those on the website. In fact, you might want to try the experiment with NaCl, since Cl-'s oxidation potential is less than that of water. For further instructions, this website has some pointers: https://learning-center.homesciencetool ... e-project/

I hope this was helpful!

Elena