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ELECTROCHEMISTRY ELECTROLYSIS MOLTEN COMPOUNDS AQUEOUS SOLUTION ELECTROLYSIS IN IDUSTRY EXTRACTION OF METALS PURIFICATION OF METALS ELECTROPLATING OF METALS.

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Presentation on theme: "ELECTROCHEMISTRY ELECTROLYSIS MOLTEN COMPOUNDS AQUEOUS SOLUTION ELECTROLYSIS IN IDUSTRY EXTRACTION OF METALS PURIFICATION OF METALS ELECTROPLATING OF METALS."— Presentation transcript:

1 ELECTROCHEMISTRY ELECTROLYSIS MOLTEN COMPOUNDS AQUEOUS SOLUTION ELECTROLYSIS IN IDUSTRY EXTRACTION OF METALS PURIFICATION OF METALS ELECTROPLATING OF METALS VOLTAIC CELL ELECTROCHEMICAL SERIES

2 ELECTROCHEMISTRY

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4 Process-a compound is decomposed into its constituents elements when electric current passes through an electrolyte Substance that can conduct electricity in molten/ aqueous solution Undergo chemical changes Substance that can conduct electricity in molten/ aqueous solution Undergo chemical changes Conductors in the form of wires, rods, or plates. It passes electricity through the electrolyte during electrolysis Inert: do not take part in chemical reactions e.g: carbon & platinum Active : take part in chemical reaction e.g: copper, silver, mercury Cathode: negative terminal Anode: positive terminal Conductors in the form of wires, rods, or plates. It passes electricity through the electrolyte during electrolysis Inert: do not take part in chemical reactions e.g: carbon & platinum Active : take part in chemical reaction e.g: copper, silver, mercury Cathode: negative terminal Anode: positive terminal ELECTROLYSIS ELECTROLYTE ELECTRODE

5 ELECTROLYSIS SETUP -molten compound-

6 Terms in electrolysis 1.Cation 2.Anion 3.Electrode 4.Inert electrode 5.Battery 6.Positive terminal 7.Negative terminal 8.Cathode 9.Anode 10.Electrolysis 11.Molten 12.Aqueous 13.Electrolyte 14.Non-electrolyte 15.Discharged

7 anioncation

8 ELECTROLYSIS OF AQUEOUS SOLUTIONS A compound water Aqueous solution NaCl solution (aq) NaCl (s) +

9 Electrolysis of NaCl solution CARBONCARBON CARBONCARBON Na⁺ H⁺H⁺ H⁺H⁺ OH⁻ Cl⁻ Na ⁺ H⁺H⁺ H⁺H⁺ Cl⁻ OH ⁻ Cathode: 2H ⁺ +2e ⁻  H 2 Cathode: 2H ⁺ +2e ⁻  H 2 Anode: 4OH ⁻  O 2 + 2H 2 O + 4e ⁻ Anode: 4OH ⁻  O 2 + 2H 2 O + 4e ⁻ e⁻e⁻

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11 Electrolytic cell

12 Electrochemical series (ECS) EASIER TODISCHARGEEASIER TODISCHARGE EASIER TODISCHARGEEASIER TODISCHARGE The lower the position of an ion in ECS,the higher is the tendency of the ion to be discharged.

13 Mari menghafal… K kalau Na nak Ca cari Mg mak Al ali Zn ziarah Fe flat Sn satu Pb pada H Hari Cu Cuti Au ahad K kalau Na nak Ca cari Mg mak Al ali Zn ziarah Fe flat Sn satu Pb pada H Hari Cu Cuti Au ahad F Fasha SO sandha NO Nok K Kahwin B Budak I India OH OH! F Fasha SO sandha NO Nok K Kahwin B Budak I India OH OH!

14 Example: Example 1: 0.5 mol dm 3 of potassium chloride, KCl solution Cations : K + and H + Anions : Cl - and OH - Cathode (negative electrode): H + move to the cathode (ions are selectively discharge) Anode (positive electrode): OH - move to the anode (ions are selectively discharge) Example 1: 0.5 mol dm 3 of potassium chloride, KCl solution Cations : K + and H + Anions : Cl - and OH - Cathode (negative electrode): H + move to the cathode (ions are selectively discharge) Anode (positive electrode): OH - move to the anode (ions are selectively discharge)

15 Example 2: 0.1 mol dm 3 of copper(II) sulphate, CuSO 4 solution Positive ions (cations): copper ions (Cu 2+ ) and hydrogen ions (H + ) Negative ions (anions): sulphate ions (SO 4 2- ) and hydroxide ions (OH - ) Cathode (negative electrode): Cu 2+ move to the cathode (ions are selectively discharge) Anode (positive electrode): OH - move to the anode (ions are selectively discharge)

16 Concentration of Ions in electrolyte Ion that have high concentration in electrolyte will be discharged.

17 Electrolysis 2.0 mol dm-3 of lead(II) bromide, PbCl 2 solution CARBONCARBON CARBONCARBON Pb 2 H⁺H⁺ H⁺H⁺ OH⁻ Cl⁻ Pb 2 ⁺ H⁺H⁺ H⁺H⁺ Cl⁻ OH ⁻ Cathode: 2H ⁺ +2e ⁻  H ₂ Cathode: 2H ⁺ +2e ⁻  H ₂ Anode: 2Cl ⁻  Cl 2 + 2e ⁻ Anode: 2Cl ⁻  Cl 2 + 2e ⁻ if 2 ions are placed very far apart in the ECS, the concentration aspect become insignificant.

18 Inert electrodes: Carbon and platinum (Both of these electrodes do not react with the electrolytes or products of electrolysis) Active electrodes: Silver, copper and nickel (Active anode ionizes and concentration of cations in the electrolyte does not change)

19 Electrolysis of CuSO 4 COPPerCOPPer coppercopper Cu 2⁺ H⁺H⁺ H⁺H⁺ OH⁻ SO4 2 ⁻ H⁺H⁺ H⁺H⁺ OH ⁻ Cathode: Cu 2 ⁺ +2e ⁻  Cu Cathode: Cu 2 ⁺ +2e ⁻  Cu Anode: Cu  Cu 2 ⁺ + 2e ⁻ Anode: Cu  Cu 2 ⁺ + 2e ⁻ SO4 2 ⁻ Cu 2⁺


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