Science Buddies: "Ask an Expert"

Time sensitive! This has not been put off. We have been searching for answers from many sources for weeks and not having any luck. 8th grade science project on manipulating a magnetic field to move through electrolysis. My daughter's science project on manipulating a magnetic field to move through electrolysis works. I need to know how and why so I can help her. Neither of us knows exactly what is happening in the process. No one else seems to know either. Could you please help? Her rough research paper is due Tuesday, 11/28/2017. The whole project is not due till February. I went to the University weeks ago and cannot seem to reconnect with the Professor for help. I'll give you what he asked for and maybe you could please help?

Salt water electrolyte.

Dye #1:
Water H20
Propylene Glycol C3H8O2
Yellow 5 C16H9N4Na3O9S2
Blue 1 C37H34N2Na2O9S3
Citric Acid C6H8O7
Sodium Benzoate C7H5NaO2

Dye #2:
Water H20
Propylene Glycol C3H8O2
Yellow 5 C16H9N4Na3O9S2
Blue 1 C37H34N2Na2O9S3
Citric Acid C6H8O7
Propylparaben C10H12O3

The #1 works and dye #2 does not. She needs to know how and why.
My knowledge of chemistry is limited to a semester in college. Every time I try to find answers, I end up with more questions. I have never seen this before.
She calls it a "Magnetic Field Motor" because it works on the principle of Lorentz force.
I can figure out that the sodium ion in dye #1 is the key but struggling with the Chemistry and Physics to explain simply and still be correct.

I get the complexities of both chemistry and physics. I get the science of saying “initiate” rather than “start”. I need “start” as much as possible. I need simple terms an 8th grader can understand. I get how complex this is and the answer can be pretty involved. It looks very simple but it is far from simple.

I need a dumbed down answer and some technical appropriate for 8th grade.









The salt water is prepared in a 90 mm X 18 mm plastic petri dish.
A neodymium magnet is at the center.
The dye is added.
The copper electrodes are placed mid way at the edges of opposite sides of the dish. Imagine a line cutting the dish and magnet in half.
Electric current is applied and the reaction begins.
Lasts about 30 to 45 seconds and up to a minute.
Begin again.

I can send video if that helps.
Please help!
Thank you!
Matt and Hannah

Hello awesome parents,

Welcome to Science Buddies! I think you are working on a really cool project and I will try to shed some light on this, but let me first tell you that my expertise is in biology, not chemistry or physics. I see you have a tight timeline, so I am going to try and see if I can help at least a little bit.

I found some links that describe this experiment. Let me know if you have seen these, or if these generate any new specific questions I can (attempt) to answer. The Sodium Benzoate is what is conducting the electricity, so that the electricity can break apart the molecules of water (H20).

Here are the links. I do hope this helps some.
https://www.exploratorium.edu/snacks/in ... ectrolysis
https://www.education.com/science-fair/ ... ctrolysis/

What you are looking for is the force on a moving electrical charge due to a magnetic field (Hall Effect). Ions moving at a right angle to a magnetic field experience a force that is at a right angle to both the motion and the magnetic field. If the motion of the ions is strong enough, they start to move the bulk of the liquid, and the dye molecules should travel with it.
I am not sure why the there is a difference between the two dye mixtures, but I suspect that the citric acid doesn't add much conductivity to the system. The sodium benzoate does dissociate (I think), but the propylparaben should not.This would give you a solid current with moving ions in the first case, but not in the second case. I would suggest that you use a multimeter (or just a light bulb that can handle the current) to check which of the two solutions actually has current running through it. Hope this helps; good luck with your daughter's project
(Do you know the concentrations and compositions of the two solutions? I assume that there must be a fair amount of benzoate and paraben in either of them)