Final answer:
A positive E°cell indicates a spontaneous redox reaction under standard conditions, meaning it occurs naturally without external energy.
Step-by-step explanation:
When E°cell is positive, the redox reaction of the cell is spontaneous. This indicates that under standard conditions, the reaction tends to occur without the need for additional energy input. The positive cell potential suggests that the reaction is likely to proceed far towards completion, with the majority of reactants converting to products. The Nernst Equation also supports this by providing a means to calculate the cell potential and determine the spontaneity of redox reactions under various conditions.
Additionally, standard electrode potentials can predict redox reaction spontaneity. By comparing the standard potentials of the cathode and anode (E° cathode > E° anode), a positive E°cell value predicts that a redox reaction will happen spontaneously. Conversely, a negative E°cell would indicate a nonspontaneous reaction, requiring external energy to proceed.