Student Ch 18 Electrochemistry

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”Never Leave till tomorrow Which u can do today " : 

”Never Leave till tomorrow Which u can do today "

Introduction & Application of Electrochemistry : 

Introduction & Application of Electrochemistry Venkatesan.J Noel Vinay Thomas Department of Chemistry Doctor of Phil.- 1st sem.

Electrochemistry : 

Electrochemistry Introduction Basic Terms in Electrochemistry Application of Electrochemistry Cells………… Fuel Cell Batteries………. Lead Acid Batteries

Electrochemistry : 

Electrochemistry Electron transfer reactions are oxidation-reduction or redox reactions. Results in the generation of an electric current (electricity) or be caused by imposing an electric current. Therefore, this field of chemistry is often called ELECTROCHEMISTRY.

Terminalogy for Redox Reaction : 

Terminalogy for Redox Reaction OXIDATIONloss of electron(s) by a species; increase in oxidation number; increase in oxygen. M M + + e – Cu Cu 2+ + 2e-- REDUCTION - gain of electron(s); decrease in oxidation number; decrease in oxygen; increase in hydrogen. M + e – M - Zn 2+ + 2e-- Zn

Application of Electrochemisry : 

Application of Electrochemisry Batteries Corrosion and coating Electroplating Electrolysis Electrochemiluminacence

Today Application Topic in electrochemistry : 

Today Application Topic in electrochemistry Cells Batteries

Reaction of Half cells : 

Reaction of Half cells Balanced half-reactions can be added together to get overall, balanced equation. Zn(s) ---> Zn2+(aq) + 2e- Cu2+(aq) + 2e- ---> Cu(s) -------------------------------------------- Cu2+(aq) + Zn(s) ---> Zn2+(aq) + Cu(s) If we know Eo for each half-reaction, we could get Eo for net reaction.

Chemical Current in External Circuit : 

Chemical Current in External Circuit To obtain a useful current, we separate the oxidizing and reducing agents so that electron transfer occurs through an external wire. .

Electrochemical cell types : 

Electrochemical cell types Concentration cell Electrolytic cell Galvanic cell Lesagne cell Fuel cell

Schematic Picture of Fuel Cell : 

Schematic Picture of Fuel Cell

Fuel Cell…. Conti…… : 

Fuel Cell…. Conti…… First demonstrated by WelshscienBst Sir William Robert Grove in 1839. First Ion Exchange fuel cell developed by W. Thomas rubb, working at GE, in 1955. Fuel cells used by NASA on Apollo, Space Shu3le, and many other space applicaBons, all supplied by United Technologies CorporaBon.

Reaction of Fuel Cell : 

Reaction of Fuel Cell Anode Reaction: 2H2 =====> 4H+ + 4e- Cathode Reaction: O2 + 4H+ + 4e- =====> 2H2O Overall Cell Reaction: 2H2 + O2 ======> 2H2O

Chemistry of fuel cell : 

Chemistry of fuel cell Process is most efficient with Pure Hydrogen Hydrogen (H2) is split at the anode into two positive Hydrogen ions (H+) and two electrons. H2 (e-) with the aid of a platinum catalyst The Electrolyte is permeable to positive ions and allows the Hydrogen to pass through…

Chemistry of Fuel cell….. : 

Chemistry of Fuel cell….. Electrons flow via a load to reunite with theHydrogen Ions to again form (H2), The flowcreates a DC electricity in the wire The hydrogen then combines with Oxygen (O2)to form Water (H2O)

Electrochemistry : 

Electrochemistry Batteries

Primary cell Batteries : 

Primary cell Batteries Alkaline battery Aluminium battery Atomic battery Bunsen cell Chromic acid cell Clark cell Daniell cell Germ battery Leclanché cell Lemon battery Lithium battery Mercury battery Molten salt battery Optoelectric nuclear battery Organic radical battery Oxyride battery Paper battery Silver-oxide battery Voltaic pile Water-activated battery Weston cell Zinc-air battery

Secondary Batteries cell : 

Secondary Batteries cell Alkaline battery Lead-acid battery Lithium-ion battery Lithium ion polymer battery Lithium-sulfur battery Molten salt battery Nickel-cadmium battery Nickel-iron battery Nickel hydrogen battery Nickel metal hydride battery Nickel-zinc battery Rechargeable alkaline battery Sodium-sulfur battery Super iron battery Super charge ion battery Vanadium redox battery Zinc-bromine flow battery

Lead Acid Battery : 

Lead Acid Battery Pb(s) + PbO2(s) + H2SO4(aq) 2 PbSO4(s) + 2 H2O(l) The cathode is made of metallic lead, and the Anode of lead dioxide The electrolyte is sulfuric acid This reaction, too, is reversible. The lead sulfate product clings to the electrodes, so applied external voltage can reverse the reaction

Mechanism of Lead Acid - Battery : 

Mechanism of Lead Acid - Battery

Uses of Lead –Acid Battery : 

Uses of Lead –Acid Battery Lead-acid batteries are referred to as “storage batteries”, because this charge-discharge cycle is so reliable These batteries were used in every automobile until quite recently The battery is discharged in order to start the engine Once the engine is running and burning gasoline, it turns an alternator which recharges the battery

Conti. : 

Conti. This process can continue for up to 5 years of normal driving After that time, enough of the lead sulfate product has been shaken off the plates that it can no longer recharge Lead-acid batteries are also used in environments where vehicles cannot emit combustion products: Indoor forklifts, golf carts, handicapped carts in airports, wheelchairs

Over all view : 

Over all view

Discussing time……….. : 

Discussing time……….. Question if any

Slide 25: 

Thank you…