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A+ CHEMISTRY, CHAPTER-3, , REACTIVITY SERIES AND ELECTROCHEMISTRY, Reactivity Series:, , , , The series obtained by arranging some of the metals in the decreasing order of their reactivity, is known as the Reactivity Series., Hydrogen is also included in this series for the sake of comparison of chemical reactivity., Potassium, Sodium, Calcium, Magnesium, Aluminium, Zinc, Iron, Nickel, Tin, Lead, Hydrogen, Copper, Silver, Gold, , K, Na, Ca, Mg, Al, Zn, Fe, Ni, Sn, Pb, H, Cu, Ag, Au, , React with dil HCl and displace hydrogen, , Do not displace hydrogen from dil. HCl, , REACTIVITY SERIES AND DISPLACEMENT REACTION:, Experiment:, , , Prepare some CuSO4 solution in a beaker 1 and ZnSO4 solution in another beaker 2., Dip a zinc plate in the first beaker and second beaker dip a copper plate., , Observation:, Beaker1, , Observation, , Before Experiment After Experiment, , Colour of Zn plate, , Ash colour, , Colour of Copper, , Colour of CuSO4 solution, , Blue colour, , Blue colour fade, , Beaker 2: No change is observed. There is no reaction., A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 1

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A+ CHEMISTRY, Conclusion:, , , , , The blue colour of CuSO4 solution is due to the presence of Cu2+ ions. When the Zn plate /rod is, dipped in CuSO4 solution, the Cu2+ ions in the solution get deposited at the Zn plate as Cu atoms., The chemical reaction is, Zn+Cu2+SO4 2-  Zn2+ SO42- + Cu, Zn is top of the reactivity series than Cu because Zn has higher reactivity than Cu., , Metals having high reactivity displace the metals having less reactivity from their salt solution., Such chemical reactions are known as Displacement Reaction, ACTIVITY, , 1. Observe the picture and answer the following., , a. In which test tube does the displacement reaction occur?, b. Write the chemical equation of the reaction., DISPLACEMENT REACTION:, , , , Oxidation is the process of loss of electrons., Reduction is the process of gain of electrons., , 1. Zinc rod is dipped in CuSO4 solution. The chemical reaction taking place given below., Zn + CuSO4  ZnSO4 + Cu., Rewrite the above equation showing the nature of ions., Zn0 + Cu2+SO42-  Zn2+SO42- + Cu0, Oxidised atom, , Zn, , Equation of oxidation, , Zn0  Zn2+ + 2e-, , Reduced atom, , Cu, , Equation of reduction, , Cu2+ + 2e-  Cu0, , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 2

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A+ CHEMISTRY, 1. Which metal was oxidised in this case?,  Cu., 2. Which metal was reduced?,  Ag, 3. Which ion is responsible for the change in colour of AgNO3 solution to blue colour after sometime?,  Cu2+ ions, 4. Write the equation oxidation and reduction?,  Oxidation: Cu Cu2+ + 2e Reduction:2Ag+1 +2e-  2Ag, Redox reaction: Cu + 2Ag+1  Cu2++2Ag., , ACTIVITY, , 1. Complete the Table, Metal, , Solution, , Displacement Reaction, , Mg, , CuSO4, , Take place, , Ag, , CuSO4, , …..a..., , Mg, , ZnSO4, , …..b…., , Mg, , AgNO3, , …..c..., , Cu, , MgSO4, , No reaction, , GALVANIC CELL, , , , Metals differ in their reactivity., Galvanic cell is an arrangement in which the difference in reactivity of metals is used to produce, electricity., , Procedure:, , , Take two beakers, one containing 100mL ZnSO4 solution and the second containing the same, amount of CuSO4 solution with the same concentration. Dip Zn rod in ZnSO4 solution and Cu in, CuSO4 solution. Connect the negative terminal of voltmeter to the Zn rod and the positive terminal to, the Cu rod. Connect the two solutions in the beakers using a salt bridge., (A long filter paper which is moistened with KCl solution can be used instead of salt bridge.), , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 4

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A+ CHEMISTRY, , Observation:, , , Electricity produced due to chemical change., , , , The electrons liberated from the Zn rod reach the copper electrode through the external circuit and, these electrons are received by copper ions in the solution changing them into copper. Chemical, equation is.., , Conclusion:, , Oxidation:, , , Zn Zn2+ +2e-, , , , Cu2+ + 2e- Cu, , , , Zn + Cu2+  Zn2+ + Cu, , Reduction:, , Redox reaction:, , Important points, , 1. Galvanic cell or voltaic cell is an arrangement in which chemical energy is converted into electrical, energy by means of redox reaction., 2. The electrode at which oxidation occurs is the anode and that which reduction occurs is the cathode., 3. Anode attains negative charge and cathode gets positive charge., 4. In galvanic cell direction of electron flow from the negative electrode(anode) to the positive, electrode (cathode)., 5. Salt bridge is a U- tube filled with a paste made by mixing gelatin or agar agar gel and a salt like, KCl, KNO3 or NH4Cl., 6. Salt bridge completes the circuit by transfer of ions and maintains the electrical neutrality of the cell., , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 5

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A+ CHEMISTRY, ACTIVITY, , a) Electron flow starts from which electrode?, b) At which electrode oxidation occurs?, c) Write down a chemical equation for the redox reaction taking place in the cell., (Hint: Zn >Fe> Ni> Sn)., GALVANIC CELL OR VOLTAIC CELL:, , , Construct Galvanic cell using Cu- Ag Electrode, , , , Silver rod, Copper rod, two beakers, Copper sulphate, salt bridge, voltameter, copper wire, water, etc., , Materials:, , Reaction:, , , , , Copper loses two electrons, and changes to Cu2+ ions and these electrons are moved towards silver, rod and Ag+ ions in the solution accept these electrons and changes to Ag., At Anode: Cu  Cu2+ + 2eAt Cathode: 2Ag+ + 2e- 2Ag., , , , Cu + 2Ag+  Cu2+ + 2Ag., , Redox reaction:, , Q: How many cells can be constructed using Zn, Cu & Ag metals?, A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 6

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A+ CHEMISTRY, Ans:, Cell, , Anode, , Cathode, , Zn- Cu, , Zn, , Cu, , Cu- Ag, , Cu, , Ag, , Zn- Ag, , Zn, , Ag, , ELECTROLYTIC CELL:, , , , , , , , , , Electrical energy is converted into chemical energy., Electricity passed through acidified water to obtain Hydrogen and Oxygen., The process of chemical change taking place in an electrolyte by passing electricity is known as, electrolysis., Electrolytes are substances which conduct electricity in molten state or in aqueous solutions and, undergo chemical change. Acids, alkalis and salts are electrolytes in their molten state or in aqueous, solution., In molten state or in aqueous solution, ions of the electrolytes can move freely. These ions are, responsible for the conduction of electricity by the electrolytes., The electrode which is connected to the positive terminal of the battery is known as anode., The electrode which is connected to the negative terminal is the cathode., Electrode at which oxidation takes place is anode and electrode at which reduction takes place is, cathode., , Comparison between Galvanic cell and Electrolytic cell :, Galvanic cell, , Electrolytic cell, , Chemical energy converted into, electrical energy, , Electrical energy is used to bring about a, chemical change, , Anode is negative, , Anode is positive, , Cathode is positive, , Cathode is negative, , Oxidation occurs at anode and reduction, at cathode, , Oxidation occurs at anode and reduction, at cathode, , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 7

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A+ CHEMISTRY, CATIONS AND ANIONS:, , , , , The positive ions which are attracted towards the negative electrode are called Cations and negative, ions which move towards anode are called Anions., During electrolysis oxidation takes place at the anode and reduction takes place at cathode., , ELECTROLYSIS OF MOLTEN SODIUM CHLORIDE, , , , , , , , , Sodium chloride in solid state is not an electrical conductor because its ions have no freedom of, movement., Electricity flows through molten NaCl., Sodium chloride melts, the positively charged sodium ions (Na+ ) and the negatively charged, chloride ions(Cl-) are free to move., Nacl  Na+ + Cl-, , Chloride ions are attracted to the positive electrode (Anode), Cl-  Cl + 1eCl + Cl  Cl2, Sodium ions reach the negative electrode (Cathode)., Na+ + 1e-  Na, Electrodes, , Chemical change, , Products, , Anode, , 2Cl-  Cl2 + 2e-, , Chlorine gas, , Cathode, , Na+ + 1e-  Na, , Sodium, , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 8

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A+ CHEMISTRY, ACTIVITY, , 1. Galvanic cells are made using the metals like Mg, Cu, Zn, and Ag. What will be the nature of, reaction in each cell?, 2. How many Galvanic cells can be made by using the metals Ag, Cu, Zn, and Mg., Prepared by:, , Sakeena T, HST PS, Iringannur Hss Calicut, , More Resources, Visit https://apluseducare.blogspot.com/, , Telegram Group: https://t.me/joinchat/ELv60hbE_g9Hvimlp0s1BA, , A+ BLOG- www.apluseducare.blogspot.com Whatsapp 9746544422, , Page 9