A battery was produced using copper metal in a solution of Cu \(^{2+}\) ions connected to rhodium metal in a solution of \(\mathrm{Rh}^{3+}\) ions. Copper is the anode and rhodium is the cathode. Is rhodium higher or lower than copper in the EMF series?

An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical changes. These cells consist of two electrodes (anode and cathode) immersed in electrolyte solutions that are connected by an external circuit and a salt bridge.

Electrochemical cells come in two main varieties: galvanic (or voltaic) cells, which convert chemical energy to electrical energy, and electrolytic cells, which do the opposite, using electrical energy to drive chemical reactions. In the context of the exercise, a battery is a type of galvanic cell where the flow of electrons from the anode to the cathode through an external circuit provides electrical power.

The reduction potential, also known as the standard electrode potential, is a measure of the tendency of a chemical species to acquire electrons and be reduced. It is measured in volts (V) and is typically found on a table of standard potentials, where the higher the value, the greater the species' affinity for electrons.

These potentials are changes in free energy for the reduction process and are determined under standard conditions, which include a 1 M concentration and a pressure of 1 atmosphere at 25 degrees Celsius. In an electrochemical cell, the electrode with the higher reduction potential will act as the cathode, and the electrode with the lower reduction potential will act as the anode.

Half-reactions are the two parts of an oxidation-reduction (redox) reaction; one half describes the oxidation process, and the other describes the reduction process. In a complete redox reaction, the oxidation half-reaction involves the loss of electrons, whereas the reduction half-reaction involves the gain of electrons.

Understanding and balancing half-reactions are essential for analyzing electrochemical cells since they represent the individual processes that occur at each electrode. When writing half-reactions, it's important to balance the number of electrons lost in the oxidation reaction with the number gained in the reduction reaction.

Oxidation and reduction are two key processes involved in redox reactions that occur within an electrochemical cell. Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. Conversely, reduction is the gain of electrons or a decrease in oxidation state.

The terms 'oxidation' and 'reduction' can be remembered by the acronym 'OIL RIG,' which stands for 'Oxidation Is Loss, Reduction Is Gain' of electrons. When these two processes occur simultaneously, ensuring that the number of electrons lost is equal to the number of electrons gained, they constitute a redox reaction.

The anode and cathode are the two electrodes found in any electrochemical cell. The anode is the electrode where oxidation occurs, and it is the source of electrons that flow through the external circuit. As a rule of thumb, anodes are where negative ions (anions) migrate to, and they have a negative sign in galvanic cells but a positive sign in electrolytic cells.

On the other hand, the cathode is the electrode where reduction takes place, and it is where the electrons flowing through the circuit are accepted. Cathodes attract positive ions (cations), and they have a positive sign in galvanic cells and a negative sign in electrolytic cells. The distinction between anodes and cathodes is crucial in determining the direction of the electron flow in the external circuit of an electrochemical cell.