A spontaneous  redox reaction happens between when Zinc and magnesium in an electrochemical cell . Use the reduction potentiachart to determine which is oxidized and which is reduced. Write the half reaction indicating the oxidation half reaction and reduction half reaction? Which metal is the anode and which is the cathode? Calculate the standard potential energy(voltage) of the cell? What kind of electrochemical cell is it? Explain

Expert Answers

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For a zinc-magnesium electrochemical cell, the half cell potentials from the standard table are:

`Mg^(2+) + 2e^- -> Mg, E = -2.38 V`

`Zn^(2+) + 2e^- -> Zn, E = -0.76 V`

From the standard half cell potential, we can see that magnesium will be reduced and zinc oxidized for the spontaneous reactions to take place.

Hence Zinc will be the cathode and Magnesium will be the anode.

The oxidation half-reaction will be:

`Zn -> Zn^(2+) + 2e^-`

The reduction half reaction will be:

`Mg^(2+) + 2e^- -> Mg`

The standard potential energy of the cell is E(magnesium) - E (zinc)

E (cell) =-2.38 - (-0.76) volts = - 3.14 volts

This is a voltaic cell, since the cell potential is negative.

Hope this helps.

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