Introduction / Context:
Batteries convert stored chemical energy into electrical energy by driving redox reactions that separate charges. Understanding the internal energy source clarifies why batteries have finite capacity, depend on temperature, and can be recharged only for certain chemistries.
Given Data / Assumptions:
- Conventional batteries (primary or secondary) with two electrodes and an electrolyte.
- Open-circuit voltage arises from electrode potentials determined by chemistry.
- No external mechanical or solar input during normal discharge.
Concept / Approach:
- Electrochemical cells perform oxidation at the anode and reduction at the cathode.
- Gibbs free energy change ΔG of the reaction relates to cell emf: E = −ΔG / (n * F).
- The chemical processes maintain ion/electron flow paths that sustain terminal voltage until reactants are depleted.
Step-by-Step Reasoning:
Chemical reactions pump charges internally, building an electric potential difference across the electrodes.External circuit connection allows electrons to flow from anode to cathode, performing work while reactions proceed.When reactants/products reach equilibrium or are exhausted, the voltage collapses.
Verification / Alternative check:
Compare with capacitors: capacitors store electric field energy directly, not chemical energy. Batteries rely on chemical conversion to sustain a quasi-constant voltage.
Why Other Options Are Wrong:
- Electronical energy: Not a standard form; electrical energy is produced, not the stored source.
- Mechanical energy: Relevant in generators, not ordinary batteries.
- Solar energy: Powers photovoltaic cells, not chemical batteries by themselves.
- None of the above: Incorrect because chemical energy is correct.
Common Pitfalls:
- Confusing batteries with capacitors or fuel cells; the underlying storage and conversion differ.
- Assuming the open-circuit voltage is set only by charge quantity rather than electrode potentials.
Final Answer:
Chemical energy
Discussion & Comments