chem ppt 06.pptx.engineeringchemistrysub

It is about chemistry subject

1. Topic: Lead Acid Storage Cell

2. Abstract: 1. What is a lead acid battery ? 2. Construction. 3. Chemical reaction for discharging. 4. Chemical reaction for recharging. 5.Applications. 6. Pros and Cons 7. Conclusion.

3. What is a lead acid battery ? The Lead-acid battery is one of the oldest types of rechargeable batteries. These batteries were invented in the year 1859 by the French physicist Gaston Plante. Lead-acid batteries can be classified as secondary batteries. The chemical reactions that occur in secondary cells are reversible The chemical process of extracting current from a secondary battery (forward reaction) is called discharging. The method of regenerating active material is called charging

4. Construction : In the lead acid battery construction, the plates and containers are the crucial components. The below section provides a detailed description of each component used in the construction. The lead acid battery diagram is

5. Working principle : As sulphuric acid is used as an electrolyte in the battery, when it gets dissolved, the molecules in it are dispersed as SO4– (negative ions) and 2H+ (positive ions) and these will have free movement. When these electrodes are dipped in the solutions and provide a DC supply, then the positive ions will have a movement and move towards the direction of the negative edge of the battery. In the same way, the negative ions will have a movement and move towards the direction of the positive edge of the battery.

6. Chemical reaction for discharging : When the battery is discharged, it acts as a galvanic cell and the following chemical reaction occurs Negative: Pb(s) + HSO4– + H2O(l) –> 2e– + PbSO4(s) + H3O+(aq) (oxidation ) Positive: PbO2(s) + HSO4–(aq) + 3H3O+(aq) + 2e– –> PbSO4(s) + 5H2O(l) (reduction)

7. Lead sulfate is formed at both electrodes. Two electrons are also transferred in the complete reaction. The lead-acid battery is packed in a thick rubber or plastic case to prevent leakage of the corrosive sulphuric acid.

8. Chemical reaction for recharging : The chemical reaction that takes place when the lead-acid battery is recharging can be found below. •Negative: 2e– + PbSO4(s) + H3O+(aq) –> Pb(s) + HSO4– + H2O(l) (reduction) •Positive: PbSO4(s) + 5H2O(l) –> PbO2(s) + HSO4–(aq) + 3H3O+(aq) + 2e– (oxidation)

9. Applications : Automotive and traction applications. Emergency power for electrical installations. Submarines. UPS (Uninterruptible power supplies) Lighting. High current drain applications.

10. Pros and cons: Pros: Low cost. Tolerant to overcharging. Low internal impedance. Can deliver very high currents. Indefinite shell life if stored without electrolyte. Wides range of sizes and capacities. World ‘s most recycled product. Cons : Dangers from chemical burns. Batteries can be heavy . Flammable gases while charging. Electrolyte can evaporate.

11. Conclusion : As they are inexpensive compared to newer technologies, lead–acid batteries are widely used even when surge current is not important and other designs could provide higher energy densities. For a few roles, modified versions of the standard cell may be used to improve storage times and reduce maintenance requirements.

12. Thank you