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The open circuit voltage of any storage cell depends wholly upon
its chemical constituents
on the strength of its electrolyte
its temperature
all of the above
all of the above
Quick Summary: The open circuit voltage (electromotive force) of a storage cell is determined by the standard electrode potential of the active materials, the chemical activity of the ions in the electrolyte, and the thermal energy of the system. Therefore, all these factors contribute to the final cell potential.
The open circuit voltage (electromotive force) of a storage cell is determined by the standard electrode potential of the active materials, the chemical activity of the ions in the electrolyte, and the thermal energy of the system. Therefore, all these factors contribute to the final cell potential.
E=E0тИТnFRTтАЛln(Q) тАФ Nernst equation relating voltage to chemicals, temperature, and electrolyte concentration
The cell potential is governed by the Nernst Equation. It shows that voltage is a function of the standard potential (derived from chemical constituents), the reaction quotient (dependent on electrolyte concentration/strength), and the absolute temperature. Changing any of these variables alters the Gibbs free energy change, thereby shifting the terminal voltage.
Chemical constituents define the standard potential (E0) of the electrodes.
Electrolyte strength (ion concentration) directly influences the reaction quotient (Q).
Temperature affects the voltage through the (RT/nF) term, as thermal energy influences ion mobility and equilibrium.
The open circuit voltage is independent of the size or plate area of the cell.
Higher temperature generally increases chemical reactivity.
Adjusting electrolyte density is used to control voltage in specific industrial applications.
Temperature fluctuations can lead to accelerated degradation of active materials.
Excessive electrolyte concentration may cause undesirable side reactions (corrosion).
Lead-acid battery design and maintenance.
Calibration of standard electrochemical cells.
Battery management systems (BMS) for SOC estimation.
The open circuit voltage (OCV) is the voltage measured when no current is flowing through the external circuit.
Option B is correct because the activity of ions in the electrolyte changes the reaction quotient in the Nernst equation.
D is correct тАФ The open circuit voltage of a cell is fundamentally determined by the Nernst equation, which explicitly depends on the chemical nature of the electrodes, electrolyte activity, and temperature.
Always remember that while OCV depends on these factors, the terminal voltage under load is further affected by the internal resistance of the battery.