Final answer:
Under specific conditions, chemists measure the standard cell potential (Eºcell) to develop a scale of relative potentials, which allows them to predict the direction and magnitude of electrochemical reactions.
Step-by-step explanation:
Under specific conditions, chemists measure the standard cell potential (Eºcell) to develop a scale of relative potentials. These conditions include all species being in their standard states (1 M for solutions), 1 atm for gases, and specific temperatures (usually 25°C). This allows chemists to predict the direction and magnitude of electrochemical reactions.