Lead-Acid Battery Discharge

Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O

Overview

During discharge, lead is oxidized to PbSO₄ at the anode while PbO₂ is reduced to PbSO₄ at the cathode, consuming sulfuric acid and producing water. The cell voltage is about 2.1 V, and six cells in series give the standard 12.6 V car battery. Invented by Gaston Planté in 1859, it remains the world's most recycled product.

Participants

Role	Substance	Coefficient	State
Reactant	Lead Pb	1	(s)
Reactant	Sulfuric Acid H₂SO₄	2	(aq)
Product	Water H₂O	2	(l)

Everyday Example

The 12V battery that starts your car every morning uses this exact lead-acid chemistry, invented over 160 years ago.

Industrial Importance

Lead-acid batteries represent a $45 billion global market. They are 99% recyclable and dominate automotive starting, UPS, and telecom backup.

Properties

Type: Electrochemical
Reversible: Yes
Energy: Exothermic
ΔH: -359.0 kJ/mol

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Frequently Asked Questions

What is the equation for Lead-Acid Battery Discharge?

The balanced equation is: Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O.

What type of reaction is Lead-Acid Battery Discharge?

Lead-Acid Battery Discharge is a electrochemical reaction. It is reversible under certain conditions.

Is Lead-Acid Battery Discharge exothermic or endothermic?

Lead-Acid Battery Discharge is exothermic (releases energy). The enthalpy change (ΔH) is -359.0 kJ/mol.