Electrolysis

• anpanman

  10 Oct 09, 20:35

  Say I want to electrolyse dilute H2SO4

  At the anode the reaction is:   4OH- -> 2H2O + O2 + 4e-

  At the cathode: 2H+ + 2e- ->H2

  Overall reaction : 2H2O -> 2H2 + O2

  I am not sure how to obtain the overall reaction. After all, water is also produced so why does the final equation not include water?

  And if we continue to electrolyse H2SO4, we will finally get a more concentrated solution. Reason being all the water is converted into molecules of H2 and O2, and with less water molecules, this leads to the solution being more concentrated with the acidic molecules. I constructed the explanation myself. The highlighted part is that included in the answers given. What does it mean by with the acidic molecules? For me, removal of water means less dilute, hence more concentrated. Any other logical way to understand this?

  Thanks !

• dkcx

  10 Oct 09, 20:39

  Originally posted by anpanman:

  Say I want to electrolyse dilute H2SO4

  At the anode the reaction is:   4OH- -> 2H2O + O2 + 4e-

  At the cathode: 2H+ + 2e- ->H2

  Overall reaction : 2H2O -> 2H2 + O2

  I am not sure how to obtain the overall reaction. After all, water is also produced so why does the final equation not include water?

  And if we continue to electrolyse H2SO4, we will finally get a more concentrated solution. Reason being all the water is converted into molecules of H2 and O2, and with less water molecules, this leads to the solution being more concentrated with the acidic molecules. I constructed the explanation myself. The highlighted part is that included in the answers given. What does it mean by with the acidic molecules? For me, removal of water means less dilute, hence more concentrated. Any other logical way to understand this?

  Thanks !

  Water is converted to H2 and O2 as its being produced so its not written in the product. You cannot have a reactant and a product being the same compound.

  Acidic molecules should refer to the H+ or H3O+ depending on which you all learn.

• yiha093

  10 Oct 09, 20:53

  however. overall eqn for electro of h2so4 is

  oh-+h+ -> h2o .

  i believe its in the tb.

• SBS n SMRT

  12 Oct 09, 13:33

  add the cathode and anode r(x)s together

  for eg

  Cathode: X + Y --> XY

  anode: Y + Z --> YZ

  overall is X + 2Y + Z --> XY + YZ