ce chem07年11題

Zn同Fe可以dissove係因為displacement reaction???

唔係. 因為 Zinc is the highest among the metals in anode in the E.C.S, Zinc 就氧化自己, 放電子, 變成 Zinc ion. 變左 ion 後, 因為佢而家 mobile, 所以就o係 solution 度. Electrolysis 係強逼性既, 逼死 D Zinc 放電子去 External Circuit 度, 所以 Zinc 唔會直接放 D 電子比隔離既 Copper(II) ion, 所以唔係 displacement reaction.

但點解Cu都可以dissolve ??

Zinc 變哂 ion 之後, 到 Iron, 先到 Copper 氧化自己, 放電子, 變成 Copper(II) ion, 入 solution.

一個metal可以dissolve 自己ion o既solution到??

可以

2008-03-31 12:48:20 補充：
Since Ag is at a lower position then Cu in the E.C.S (Ag is a weaker reducing agent then Cu), Ag cannot oxidize itself to give electron to copper through the external circuit. 所以你說得對.

2008-04-02 12:20:55 補充：
應該係 hydroxide ion oxidizes 掛 =,= OH- ge reducing power 勁過 Cu

in the anode , oxidation occurs. copper will lose electron and
become copper ii ion and move to the solution.
at the cathode, copper ii ion will deposite on the copper rod,
where reduction occurs.