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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Pepealej on January 05, 2013, 06:25:44 PM

Title: Water electrolysis with H2SO4/Na2SO4
Post by: Pepealej on January 05, 2013, 06:25:44 PM

Hi everyone. I'm new to this forum and wanted to start by asking for help with one question I have.

I've got a question on water electrolysis using sulfuric acid. In the process, will all the sulfuric acid be used up? What will happen with it? How do I know?

Thanks :)

Title: Re: Water electrolysis with H2SO4/Na2SO4
Post by: Pepealej on January 05, 2013, 06:29:13 PM

Hi. I'm new to this forum and wanted to ask one question.

My question is regarding water electrolysis with Na₂SO₄. I've used thymol blue too. My question is: Why does the color change in the proximities of the electrodes during the electrolysis?

I suppose this is due to a change in pH, but I don't know how to explain it. Can anybody give me a hand?

Thanks :)

Title: Re: Water electrolysis with H2SO4/Na2SO4
Post by: Borek on January 06, 2013, 04:28:08 AM

These questions are closely related, so it is better to have them in one thread.

What have you observed (apart from indicator color changes)? Write reaction equations explaining your observations.

Title: Re: Water electrolysis with H2SO4/Na2SO4
Post by: Pepealej on January 06, 2013, 06:08:50 AM

I've observed the standard water electrolysis.

The H2SO4 dissociates and thanks to its ions the electrolysis can take place. The global reaction is: H₂O (l)  :rarrow: H₂ (g) + 1/2 O₂ (g).

Nothing else.

Title: Re: Water electrolysis with H2SO4/Na2SO4
Post by: Borek on January 06, 2013, 06:53:52 AM

That's a correct overall reaction. Can you split it into the cathode and anode parts?