chem electrolysis

樓上個位又唔係錯唔曬...不過好似miss左個重點.....
其實可以唔多理Pt容唔容易lose electron or oxidized 去變ion( 其實咁諗直頭錯, 因為Pt係好stable, 唔會係呢D case變ion form, 正如用graphite做electrode的原因)
樓上所講係simple chemcial cell就係咁諗, 呢個case係electrolysis

electrolysis of concentrated sodium chloride solution唔可以用platinum的因為係Cl-會"attack"platinum.(As chloride ion will attack the platinum electrode)

就個point係short Q都會考, 要記得呀!

係CE來說,, Chlorine ion is preferentially discharged into chlorine at anode.

2Cl- -> Cl2 + 2e-

你只需要答: Cl2 will attack plantium electrode during electrolysis.

Hope my explanations help.

http://www.ehow.com/how-does_4927039_metal-electrolysis-work.html

首先，我建議你睇明呢篇文章，大致內容係你講既METAL會擺係負極CATHODE而唔係ANODE︳而ANODE(陽極)係可以用來擺一件你想ELECTROPATING 既物件。

咁現在我用依段英文來解釋甚麼係ELECTROLYSIS(電解). 留心LA。

Whenever different metals are placed in a conductive liquid you create a battery. If you connect these pieces of metal together, current will flow. The current will be removing metal from one of the metal pieces = "electrolysis".
老實講，我雖然已經離開中四化學課程有10個年頭LA，但有一樣野仍然記得，所以可以解答你的問題。用簡單的解說去回答你的問題，就係dIFFERENT METAL has Different reactivity in electrolytic reactions. 如zinc(鋅)，它在sodium cholride 會被ionized, (ie. zinc is ionized in solution NaCl to form zinc 2+ ions. ) 可見zinc form的positive ions的charge is 2, charge 越高，代表metal越高reactivity in electrolysis. 又如aluminium, Al，它被ionized 後是form Al3+的ions, 這代表aluminium係十分適合用於electrolysis of concentrated sodium chloride solution. 而platinum，係一種稱為transition elements的金屬，這個element所具有既特性就是The transition elements have low ionization energies. 但唔代表platinum唔可以在electrolysis 用到，唯一的困難在於sodium chloride is not an acidic solution. 即係話，platinum需要在強酸作傳導才能被ionized 出幾種唔同的+ve ions,

如果係我答，就會答因為NaCl不是一種acidic solution but is a neutral solution with Ph about 7. 雖然唔知我答唔答到你要既答案，但係你可以試下去問，同多了解一下每樣metal 的ionic charge。