Difference between carbon electrodes and copper electrodes
Answers
Answered by
5
Well, In electrolysis, positive electrode = anode (oxidation takes place); negative electrode = cathode (reduction takes place)
This question requires basic understanding of standard electrode potentials.
When using copper electrodes, it's basically electroplating an object at cathode with copper. Electrons are gained at the cathode and electrons are lost at anode. Hence anode becomes thinner as it "dissolves" in the solution. Cathode/object at cathode becomes heavier/thicker. The colour intensity of the solution remains the same, because as copper ions are reacting at the cathode, copper ions are given out at the anode.
When using carbon (graphite) electrodes, it's the "battle" between the copper cations and hydrogen cations. Referring to the standard electrode potentials of Cu2+ and H+, you'll realise that
Cu2+ + 2e- -> Cu : 0.34V
H+ + e- -> 0.H2 : 0.00V
Reaction for Cu2+ is more positive, so this reaction is more favorable. So at cathode, you'll see reddish brown solid (copper) deposited on the carbon electrode. As copper cations are used up in this reaction, the solution becomes paler blue in colour.
At the anode, hydroxide ions are the only anions that can react, as this is not an acidified solution of hydrogen sulphate. Hence oxygen is produced at the anode.
Hope this helps!
This question requires basic understanding of standard electrode potentials.
When using copper electrodes, it's basically electroplating an object at cathode with copper. Electrons are gained at the cathode and electrons are lost at anode. Hence anode becomes thinner as it "dissolves" in the solution. Cathode/object at cathode becomes heavier/thicker. The colour intensity of the solution remains the same, because as copper ions are reacting at the cathode, copper ions are given out at the anode.
When using carbon (graphite) electrodes, it's the "battle" between the copper cations and hydrogen cations. Referring to the standard electrode potentials of Cu2+ and H+, you'll realise that
Cu2+ + 2e- -> Cu : 0.34V
H+ + e- -> 0.H2 : 0.00V
Reaction for Cu2+ is more positive, so this reaction is more favorable. So at cathode, you'll see reddish brown solid (copper) deposited on the carbon electrode. As copper cations are used up in this reaction, the solution becomes paler blue in colour.
At the anode, hydroxide ions are the only anions that can react, as this is not an acidified solution of hydrogen sulphate. Hence oxygen is produced at the anode.
Hope this helps!
Similar questions