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Brine electrolysis: question

  1. Oct 7, 2007 #1
    hello. i'm new member here. i have some question regarding my brine electrolysis experiment. really hope somebody can help me. i'm using saturated brine in the compartment and graphite as electrode at anode and cathode. i can see the reaction at the anode and cathode was very vigorous and many bubble coming up from the reaction. hopefully there was chlorine gas collected at the anode (i still do not test that gas). my questions are: (1) can i used the same graphite electrode for the 2nd experiment? will the reaction be the same or the effectiveness will decrease? (2) i've read some information said that only 30% of brine in water is enough for this experiment. is that true? which one will produce more chlorine gas, 30% concentration of brine or saturated brine? (3) based on my experiment, the reaction seems stopped after half an hour later. why this happen? what should i do to continuously produce chlorine gas? (4) i'm using 9volts batery for this experiment. is that ok? what is the most effective voltage/current sholud i used?
  2. jcsd
  3. Oct 12, 2007 #2
    what IS the second experiment?? as far as i remember, the only way for graphite to become unusable is through oxidation; but here Cl- is preferentially discharged...so you wouldn't get oxygen..... i believe you can still use the grphite electrode....

    as long as Cl- is found in a greater concentration than OH-, Cl- will be preferentially discharged. The higher the conc of the brine, the more Cl2 you will get obviously.

    and to get more Cl-, increase its concentration......

    Chlorine is normally a pale green/yellow gas,...so you would be able to see if it is formed. but i think most will dissolve in the water.

    i did electrolysis only last year....so i might be wrong...better confirm it
  4. Oct 23, 2007 #3
    graphite become unusable

    i already test the gas. it is chlorine gas. but when i used the same graphite for the other experiment, it seem like become unusable. the reaction (bubbles produce) was very very slow compared to the first experiment. why this thing happens? what should i do to continuously produce chlorine gas from the experiment.
  5. Oct 23, 2007 #4


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    You may find some answers here. Did you measure the pH of your brine in the second experiment?
  6. Jul 28, 2010 #5
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