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Specialty Chemistry Forums => Citizen Chemist => Topic started by: DFliyerz on November 27, 2014, 08:03:11 PM

Title: Electrolysis of Potassium Chloride Problem?
Post by: DFliyerz on November 27, 2014, 08:03:11 PM

I've been electrolysing a solution of water and potassium chloride in an attempt to make potassium hydroxide, when I ran into a problem; all of a sudden, it stopped bubbling at the electrodes! I played around with the power supply, added more potassium chloride, and even switched electrodes, all to no avail. The pH hasn't changed, but there is a slight pool-like smell over the container. Any idea what happened?

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: billnotgatez on November 28, 2014, 12:17:38 AM

What kind of electrodes?
What are the various settings are you using on the power supply?
Why are you sniffing the resultant gasses?
What does you setup look like?

I am concerned about the safety of what you are doing.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: Borek on November 28, 2014, 02:49:32 AM

Are you controlling current? Is it still flowing when the bubbling stops?

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: Zyklonb on November 28, 2014, 11:11:40 AM

Most likely there's a problem with you PSU. Also, are you using a salt bridge? If not you will make mostly potassium chlorate and perchlorate, not hydroxide. Additionally, any anode you use will dissolve quickly except MMO, Pt, lead dioxide, and a handful of even harder to aquire materials.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: DFliyerz on November 28, 2014, 12:34:11 PM

I'm using carbon electrodes, I can only adjust the voltage on my power supply, and I only smelled the resultant gasses when leaning over the container to look at what was going on inside. Additionally, I am not using a salt bridge.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: Borek on November 28, 2014, 12:54:13 PM

If you don't know what the current is, how can you be sure it is not just a matter of lost contact on the electrode?

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: DFliyerz on November 28, 2014, 01:14:27 PM

Quote from: Borek on November 28, 2014, 12:54:13 PM

If you don't know what the current is, how can you be sure it is not just a matter of lost contact on the electrode?

I also tried just bare copper wire, and still to no avail.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: DFliyerz on November 28, 2014, 05:20:18 PM

EDIT: Turns out, there was a current dial, and it's not giving any current! Thanks for your *delete me*

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: Enthalpy on November 28, 2014, 05:40:23 PM

The pool smell is hypochlorite. It's a usual product of chloride electrolysis.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: Zyklonb on November 28, 2014, 07:53:40 PM

You mean chlorine. Which can be produced by hypochlorite decomposing.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: billnotgatez on November 28, 2014, 07:58:40 PM

@DFliyerz
You might give a thorough read of the following link
http://en.wikipedia.org/wiki/Chloralkali_process

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: billnotgatez on November 28, 2014, 08:17:59 PM

@Zyklonb

can you define the abreviations

PSU
MMO

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: Zyklonb on November 28, 2014, 10:00:36 PM

Sorry, PSU is used in computer terminology for power supply unit.
MMO - mixed metal oxide. The anode material used industrially in chlorate and chloralkali cells. It's a titanium mesh with several inert oxides plated on it, generally iridium, platinium, ruthenium and several others.
BTW, I'm selling some Ir MMO at the moment, in case anyone wants some it's $3.00/ sq inch. PM me for details.

Title: Re: Electrolysis of Potassium Chloride Problem?
Post by: billnotgatez on November 28, 2014, 10:15:17 PM

Quote

BTW, I'm selling some Ir MMO at the moment, in case anyone wants some it's $3.00/ sq inch. PM me for details.

I am going to have to have a chat with Santa  ;)