related to voltaic cell and elecrolytic cell

[[Announcements] [Introduce Yourself] [ICT] [Prasekolah] [LINUS] [KSSR] [UPSR] [PMR] [SPM] [STPM] [School] [Classroom] [Clubs & Uniformed Bodies] [JPN] [SPA] [SICT] [SPP] [SPS] [SPPK] [SPSPK] [SPI] [SPsK] [JNJK] [PPD] [Program] [Computer & Internet] [Let's Hear It From You] [Membergroup]]

[Announcements] [Introduce Yourself] [ICT] [Prasekolah] [LINUS] [KSSR] [UPSR] [PMR] [SPM] [STPM] [School] [Classroom] [Clubs & Uniformed Bodies] [JPN] [SPA] [SICT] [SPP] [SPS] [SPPK] [SPSPK] [SPI] [SPsK] [JNJK] [PPD] [Program] [Computer & Internet] [Let's Hear It From You] [Membergroup]

[Loh Tze Hoon]

To all teacher,
For your information anode in electrolytic cell is known as positive terminal, and anode in voltaic cell is known as negative terminal. Both anodes are occuring same process which is oxidation where there is releasing of electron. Is there any explaination for why anode in voltaic cell is negative but for electrolytic cell is positive?
May I have a detail explaination? Thanks a lot.

[Sim Thiam Huat]

My chemistry teacher taught me this explanation and i'm using it till today
  " Anode or cathode is defined as the electrode where current enters or leaves a solution"
     [b]Anode[/b] is electrode where current enters the solution and [b]cathode[/b] is electrode where current leaves the solution

[Jong Kah Yin]

Anode and cathode is determined by the process that occurred at the electrodes. In anode, oxidation occurs whereas in cathode, reduction occurs.
In electrolytic cell, anode is positive by virtue that it is connected to the positive terminal of the power supply and vice-versa.
In voltaic cell, anode is negative because the metal used at anode is more electropositive, hence it will release electrons easily. Therefore, we expect the electrons released to accumulate at the electrode, electrons has a negative charge, thus causing the anode to be negative terminal.
Hope I answer your questions.

[Loh Tze Hoon]

Thanx for the answer first,
but if the electrons accumulated at anode for voltaic cell as the oxidation going on, then there is also electrons accumulated at anode in electrolytic cell as the oxidation also going on at the anode..so why is it anode for voltaic cell is negative terminal but electrolytic cell is positive terminal? or we can say it is not metal and not that eletropositive, so no electron will be accumulated at anode of electrolytic cell?
How about the current entering the electrode, actually it is from cathode to anode through external circuit or internal tru the solution?
  thanks again...

[Sim Thiam Huat]

In electrolysis, anode is connected to the positive terminal of a cell, Current flows (opp. direction to electron) from the positive terminal of the  power supply in the external circuit into the anode(into the solution). At cathode, current leaves the solution and go back to the negative terminal of the power supply thru the wire.
In a cell, say zinc/copper pair of electrodes. Zinc being the more electropositive metal is negative ( electrons leave this electrode , so current being flowing in the opp. direction enters the solution thru the external wire thru this zinc electrode, so zinc is anode. At the copper electrode(positive), electrons enter but current leaves - leaves the solution, so leaving the solution is cathode by definition. hence Copper (positive) is cathode.
Please make a sketch of the 2 cells and follow this explanation of current entering or leaving the solution. I find it explains well. I wouldn't use the concept of oxidation/reduction because in form 4, the students do not study it yet. Hope it helps.

[Liew Hui Lee]

In the electrolytic cell, the anode is connected to the positive terminal of the dry cells (power supplier), so the anions will attrach to the anode ( oppositely-charged particles attrach each other )and released electrons here, as anode or positive terminal accepts electrons, reduction occurs.
In the voltaic cell, the anode is the more electropositive metal, eg. zinc.  Zinc will release electrons to form zinc ions.  Here, the accumulation of electrons occurs and make it negatively in charge and acts as negative terminal.  As zinc release electrons ( for the zinc electrode its own ), oxidation occurs.

[Liew Hui Lee]

The current flow is only occurs when the circuit is compeleted.  To complete the circuit there must be the movement of ions through the electrolyte ( solution ) and the electrons flow through the external connecting wires.
The current flows in the opposite direction of the electrons flow.  Therefore, during we use the ammeter / galvanometer during the electrolysis, the indicator of the instruments will deflect from cathode to anode showing that the electrons flow from the anode to cathode through the external connecting wires.

[Loh Tze Hoon]

ok, get it..
thanks a lot 

Advanced search