Since our overall reaction includes magnesium solid in the reactants, we must invert the first equation, including the sign of the electrical potential.

This cell is galvanic because the electrical potential, , is positive. Galvanic cells involve spontaneous reactions, and therefore, do not need any external energy source to drive the reaction.

Since our overall reaction includes calcium solid in the reactants, we must invert the second equation, including the sign of the electrical potential.

This cell is electrolytic because the electrical potential, , is negative. Electrolytic cells involve nonspontaneous reactions, and therefore, must have an external voltage source such as a battery to drive their reactions.

Using the equation: , for a spontaneous reaction to occur,  must be positive. With solid zinc as the reactant, any other solid can act as the product, and still give a positive . This is because, subtracting a negative number will give a positive value.

As a result, the equation,, will become inverted to make the solid zinc a reactant. . Solid zinc will give electrons, and oxidize, to reduce other ions. 

First we must rearrange the reduction potentials so that when added together, they match the reaction that takes place in the electrochemical cell.

In the overall reaction,  is in the reactant side, so the  equation must be inverted.

Use the equation:  to find the . 

 is product, while  is the reactant.

The cell must be electrolytic because the  value is negative. This means, this the reaction is a non-spontaneous reaction and need a applied energy source to make the reaction take place.

Oxidation always takes place at the anode, regardless of the electrical cell type. The charges on the anode and cathode are reversed between galvanic and electrolytic cells. In electrolytic cells, the cathodes are marked negative and the anodes are marked positive. In galvanic cells, the reverse is true: cathodes are marked positive and anodes are marked negative.

Oxidation always takes place at the anode, regardless of the electrical cell type. The charges on the anode and cathode are reversed between galvanic and electrolytic cells. In electrolytic cells, the cathodes are marked negative and the anodes are marked positive. In galvanic cells, the reverse is true: cathodes are marked positive and anodes are marked negative.

Remember the acronym "OIL RIG:" Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).

In the above reaction tin loses two electrons, and is oxidized in the process. Iron is reduced because each iron ion gains an electron.

Reduction: 

Oxidation: 

In an electrical cell, oxidation always takes place at the anode. As a result, tin is oxidized at the anode.

The reduction half reaction always takes place at the cathode. As a result, we are looking for the half reaction in which electrons combine with an ion in order to produce a metal product. Remember that reduction is a gain of electrons.

For the redox reaction above, copper ions are reduced in order to form copper metal. Since this is the reduction reaction, it must occur at the cathode.

Reduction: 

Oxidation: 

It does not matter if the cell is galvanic or electrolytic; oxidation will always take place at the anode. This means that the nickel loses two electrons and is oxidized at the anode to generate nickel ions.

Nickel ions and iron are products, and are neither oxidized nor reduced during the reaction. Iron ions are reduced at the cathode to generate the iron product.

Remember: AN OX and RED CAT (the ANode is the site of OXidation, and REDuction takes place at the CAThode). Also remember OIL RIG (Oxidation Is Loss of electrons and Reduction Is Gain of electrons). The question asks us which species is produced at the cathode (site of reduction). Also, remember that electrons always flow from anode to cathode, and that galvanic cells are spontaneous reactions (positive ), and since electrons are negatively charged, they spontaneously flow from the anode (negative cell) to the cathode (positive cell) according to the law of attraction.  is being produced at the anode because electrons are being transferred from the anode to the cathode. In this case, the lithium ions are gaining electrons to form solid lithium at the cathode. Solid potassium is losing electrons at the anode to form .