A redox reaction occurs in an electrochemical cell, where Ag is oxidized and Ni is reduced. Write a half reaction for this reaction indicating the half reaction oxidized and half reaction reduced.
What is the anode and cathode.
Calculate the standard voltage of the cell.
What kind of electrochemical cell is it?
In voltaic cells, also called galvanic cells, oxidation occurs at the anode and reduction occurs at the cathode. A mnemonic for this is "An Ox. Red Cat." So since silver is oxidized, the silver half-cell is the anode. And the nickel half-cell is the cathode.
Another mnemonic is "OIL RIG". Oxidation Is Loss. Reduction Is Gain (of electrons). Since Silver is oxidized, silver loses 1 or more electrons. Silver loses 1 electron because it only forms a +1 charge (oxidation state). So the oxidation half-reaction is:
Ag ------> Ag^+1 + 1 e^-1. (The electron lost is produced and travels through the cell.)
Nickel is reduced which means it gains 1 or more electrons. In this case, The nickel(II) ion gains 2 electrons to form neutral nickel:
Ni^2+ + 2 e^-1 ---------> Ni
Using the table of reduction potentials, the overall standard voltage of the cell can be calculated. E cell = E cathode - E anode
E cell = -0.25 - 0.80 = -1.05 V
Since the cell potential is negative, this is a voltaic cell (aka galvanic cell). Hope this helps!