Describe galvanic cells that use the following reactions. In each case, write the anode and cathode half-reactions and sketch the experimental setup. Label the anode and cathode, identify the sign of each electrode, and indicate the direction of electron and ion flow. (b)

Key Concepts

Galvanic Cells

Galvanic cells, also known as voltaic cells, are electrochemical cells that convert chemical energy into electrical energy through spontaneous redox reactions. They consist of two half-cells, each containing an electrode immersed in an electrolyte. The anode is where oxidation occurs, releasing electrons, while the cathode is where reduction takes place, accepting electrons. This flow of electrons generates an electric current, which can be harnessed for external work.

Half-Reactions

Half-reactions are the individual oxidation and reduction processes that occur in an electrochemical cell. Each half-reaction shows the transfer of electrons and the change in oxidation states of the reactants. In a galvanic cell, the anode half-reaction involves the loss of electrons (oxidation), while the cathode half-reaction involves the gain of electrons (reduction). Understanding these half-reactions is crucial for determining the overall cell reaction and the flow of electrons.

Electrode Sign and Ion Flow

In a galvanic cell, the anode is designated as negative and the cathode as positive due to the flow of electrons from the anode to the cathode. This flow of electrons is accompanied by the movement of ions in the electrolyte; cations migrate towards the cathode, while anions move towards the anode. This charge separation is essential for maintaining electrical neutrality in the cell and is a key factor in the operation of galvanic cells.