A rechargeable battery with lead and lead dioxide plates in sulfuric acid, used in vehicles.
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A lead-acid battery has a lead anode and a lead dioxide cathode immersed in sulfuric acid of about 30 to 40 percent by mass. Each cell gives about 2 V, so six cells in series produce the 12 V used in vehicle starter batteries. During discharge both electrodes are converted to lead sulfate and acid is consumed, so the density of the electrolyte falls and indicates the state of charge. The battery is rechargeable because the lead sulfate can be reconverted to lead and lead dioxide by reversing the current. It is valued for its ability to deliver high surge currents.
Key ideas: Discharge: Pb + PbO2 + 2H2SO4 giving 2PbSO4 + 2H2O, about 2.0 V per cell, with six cells making 12 V. Anode Pb, cathode PbO2, 4 to 5 M H2SO4. State of charge is checked by acid density (1.28 g/mL full, 1.10 empty). Charging reverses the reaction.
Common mistakes and connections: Mistakes: thinking sulfuric acid is not consumed (it is, so density falls), and overcharging produces H2 and O2 by water electrolysis (explosion hazard). Sulfation, hard PbSO4 on plates, reduces capacity. High current for starter motors, and recycled at over 95 percent. Pb is toxic, so recycling is essential.
In a lead-acid cell both plates turn to PbSO4 on discharge, consuming sulfuric acid; each cell gives about 2 V and six in series make 12 V. The interactive lesson shows this as a live animation or chart.
A fully charged car battery has an electrolyte density of about 1.28 g/cm3, which falls as the battery discharges.
A rechargeable battery with lead and lead dioxide plates in sulfuric acid, used in vehicles.
Lead-Acid Battery is a intermediate topic in Acids, Bases & Electrochemistry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Acids, Bases & Electrochemistry first: Chlor-Alkali Process, Dry Cell, Alkaline Battery.
The next topics in Acids, Bases & Electrochemistry are Lithium-Ion Battery and Nickel-Metal Hydride Battery.
Yes. The interactive lesson includes a self-check question on Lead-Acid Battery, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Lead-Acid Battery is topic 70 of 105 in Acids, Bases & Electrochemistry.