DETERMINATION OF EMF CELL || (ELECTROCHEMICAL/GALVANICA/DANIEL) CELL || @Experiment Talk скачать в хорошем качестве

DETERMINATION OF EMF CELL || (ELECTROCHEMICAL/GALVANICA/DANIEL) CELL || @Experiment Talk

What is Electrochemistry? Electrochemistry is the study of the interchange of chemical energy and electrical energy. The process of conversion of chemical energy into electrical energy is called electrochemical reaction and the reverse process is called electrolytic reaction or electrolysis. A device that produces electrical energy from a chemical reaction is called an electrochemical cell and devices that undergo chemical reaction with the aid of electricity are called electrolytic cells. Galvanic Cell : A galvanic cell is an important electrochemical cell. It is named after Luigi Galvani an Italian physicist. It is also called Voltaic cell, after an Italian physicist, Alessandro Volta. A galvanic cell generally consists of two different metal rods called electrodes. Each electrode is immersed in a solution containing its own ions and these form a half cell. Each half cell is connected by a salt bridge, or separated by a porous membrane. The solutions in which the electrodes are immersed are called electrolytes. The chemical reaction that takes place in a galvanic cell is the redox reaction. One electrode acts as anode in which oxidation takes place and the other acts as the cathode in which reduction takes place. The best example of a galvanic cell is the Daniell cell. Daniell cell : The Daniell cell was invented by a British chemist, John Frederic Daniell. In the Daniell cell, copper and zinc electrodes are immersed in a solution of copper (II) sulfate (CuSO4 (aq)) and zinc (II) sulfate (ZnSO4 (aq)) respectively. The two half cells are connected through a salt bridge. Here zinc acts as anode and copper acts as cathode. At the anode, zinc undergoes oxidation to form zinc ions and electrons. The zinc ions pass into the solution. If the two electrodes are connected using an external wire, the electrons produced by the oxidation of zinc travel through the wire and enter into the copper cathode, where they reduce the copper ions present in the solution and form copper atoms that are deposited on the cathode. What is a Salt Bridge? The salt bridge is usually an inverted U-tube filled with a concentrated solution of an inert electrolyte. The inert electrolyte is neither involved in any chemical change, nor does it react with the solutions in the two half cells. Generally salts like, KCl, KNO3, NH4NO3 are used as the electrolyte. Electrode potential:- When a metal electrode is dipped in a solution containing its metal ions, a potential difference is developed at the metal solution interface. This potential difference is called the electrode potential. For example, when a zinc rod is dipped in a solution containing Zn2+ ions, it oxidizes, and the Zn2+ ions pass from the zinc rod to the solution leaving excess of electrons at the zinc rod. Thus the zinc rod becomes negatively charged with respect to the solution and a potential difference is set up between the zinc rod and the solution. This potential difference is called the electrode potential of zinc. Similarly, when a copper rod is dipped in a solution containing Cu2+ ions, the Cu2+ ions gain electrons from the copper rod leaving positive charge on the copper rod. As a result a potential difference is set up between the copper rod and the solution and is called the electrode potential of copper. In an electrochemical cell, the anode has a negative potential and cathode has a positive potential.The potential of each individual half cell cannot be measured. We can measure only the difference between the potential of the two half cells. The potential of a half cell can be measured by connecting it with Standard Hydrogen Electrode (SHE). The standard electrode potential of a SHE is assumed to be zero. The electrode potential at standard conditions such as 25°C temperature, 1 atm pressure, 1 M concentration of electrolyte, is called the standard electrode potential. It is denoted by the symbol E0. The electrodes are arranged in the increasing order of their standard reduction potential and are called electrochemical series. Electromotive Force (emf) OR Cell Potential The potential difference between the two electrodes in a galvanic cell is called a cell potential or emf of the cell. It is measured in volts. emf of the cell = Potential of the half cell on the right hand side (Cathode) - Potential of the half cell on the left hand side (Anode) For example, #emf_of_Daniell_cell #EXPERIMENT_TALK #ALL_EXPERIMENT_CHANNEL #EXPERIMENT_CHEMISTRY #EXPERIMENT_PHYSICS #SAYSTALK