Electrolysis Products: NaCL vs MgCL: 9th Grader's Science Fair

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Discussion Overview

The discussion revolves around a 9th grader's science fair project comparing the electrolysis of NaCl and MgCl solutions to determine which produces more hydrogen gas. Participants explore the chemical reactions and products formed during the electrolysis process, including the observations made after applying a current.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant questions the amount of water used in the experiment and notes the absence of voltage information.
  • Another participant discusses the ions present in the NaCl solution and suggests that the brownish residue observed may be a copper compound, listing several possibilities such as CuOH, Cu(OH)2, Cu2O, CuCl, and CuCl2.
  • A participant prompts further investigation into the MgCl2 solution, asking what species are present and what compounds could form during electrolysis, particularly those that might result in a milky white precipitate.
  • There is an emphasis on the need for further research to identify the specific compounds formed in both solutions during electrolysis.
  • The 9th grader inquires about Faraday's law of electrolysis, indicating an interest in the theoretical framework behind the experiment.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific products formed during electrolysis or the implications of the observations made. Multiple viewpoints and questions remain regarding the reactions taking place in both solutions.

Contextual Notes

Participants highlight the need for additional information, such as the voltage applied and a clearer understanding of the chemical species involved, which could affect the interpretation of the results.

Who May Find This Useful

This discussion may be useful for students and educators interested in electrolysis, chemical reactions, and experimental science fair projects, particularly at the high school level.

esaltzman
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I am a 9th grader working on a science fair project to determine which salt, NaCL or MgCL produces the most hydrogen gas through electrolysis. I used 1.5 ml of water for each, and 17.5 mg of each salt respectively. After 1 hour of applying a 2.5 amp current through each sample, the NaCL solution formed a brownish residue, while the magnesium chloride solution had turned milky white. What reactions had taked place, and what were the product(s)?

P.S. The wires in the water were copper.
 
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used 1.5 ml of water for each, and 17.5 mg of each salt

sure it 1.5ml of water?

You do not state what voltage .

Nonetheless,
NaCl solution
You have ions H+, Na+, Cl-, and OH- in solution
The electrode is copper and that can form oxidatin states of +1, +2, +3, +4

You know that the other ions can form compounds but not with a brown color,

so the brownish residue is some sort of copper compound assuming only +1, +2 oxidation
It could be CuOH, CU (OH)2, , Cu2O, CuCl, Cu Cl2

Does that help you out?
 
Thanks so much! Have any thoughts on the MgCl2 solution?
 
Do the same thing for the MgCl2 solution.
When the solution is prepared, what species are present in solution.
Then, as the electrolysis is performed what compounds have a possibility of being formed.
Of those compunds, what forms a milky white precipitate suspended in the water, but most likely something to do with Mg.

Note that for the NaCl solution you still have to decide which one compound has formed the browniish residue, instead of a brownish liquid, which since you say residue is not soluable in water.

You still have some more research to do.
Come back if you have some more questions.

Sorry if I appear to be vague but you trying to find out what the precipitates are will give you tremendous insight into chemical reactions.
 
esaltzman said:
I am a 9th grader working on a science fair project to determine which salt, NaCL or MgCL produces the most hydrogen gas through electrolysis.

Do you know Faraday's law of electrolysis?
 

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