TRAVISTRA

 THERMOGRAVIMETRIC ANALYSIS It is a thermal analytic technique in which the mass of a substance is measured as a function of increasing temperature. As the temperature increases, the sample undergoes physical and chemically changed will be accompanied by mass loss.  It is used to determine a material’s thermal stability and its fraction of volatile components by measuring the weight change.  It is carried out in air or inert atmosphere such as nitrogen, helium, or Argon.  The graph obtained is known as a thermogram. It is a plot of mass vs temperature. It can provide information about physical phenomena such as vaporization, sublimation. Absorption, adsorption, and desorption. And chemical phenomena like chemisorption, dehydration, decomposition, oxidation, and reduction.  WORKING OF TGA The sample is placed in a crucible or shallow dish that is attached to an automatic recording balance and is continuously heated by the power source. The weight change of the sa...

 CATHODIC PROTECTION  It is a method of preventing a metallic object from corrosion. It is an electrochemical process in which the metal which is to be protected is forced to act as a cathode. Corrosion occurs only in the anodic area. Therefore the entire surface of the metal can be turned into a cathode, then corrosion can be prevented. In this case, corrosion is not actually eliminated but moved to a known location by adding an anode, which undergoes slow and controlled corrosion. There are two main methods of applying  cathodic protection: Sacrificial anode protection and Impressed current cathodic protection SACRIFICIAL ANODE PROTECTION In this method, the metallic structure which is to be protected is connected to a more anodic metal through a wire, so the entire corrosion is concentrated on the anodic metal, and the metallic structure is protected sacrificially. Anode metals commonly used for this are Mg, Zn, Al, and its alloys.   They are based on the position...

 LITHIUM-ION BATTERY Lithium-ion batteries are secondary rechargeable batteries.  It has an emf that varies from 3.5-4V depending on electrode potential. Construction The 3 primary components of a lithium-ion battery are: The anode is lithiated graphite (graphite in which lithium ions are inserted in between the layer of carbon atoms. The cathode is a mixed metal oxide like LiCoO2,  LiMnO2 or LiFeO2  The electrolyte is a lithium salt (LiPF6, LiBF4, or LiClO4 ) in an organic solvent. This is rechargeable. This is done by applying a higher voltage than the voltage of the battery, across the electrodes. The lithium-ion moves from anode to cathode during discharging and from cathode to anode while charging. Cell reaction Anode : LixC6  --->   6C + x Li+  + x e- Cathode : Li1-x CoO2 + x Li+  + xe ----->   LiCoO2 Overall cell reaction : LixC6 + Li1-x CoO2  ------->   LiCoO2  +6C Characteristics Depending on ...

STANDARD HYDROGEN ELECTRODE  The standard hydrogen is an example of a glass electrode, used as a primary reference electrode whose electrode potential is fixed as zero.  CONSTRUCTION OF SHE Hydrogen gas at 1atm pressure is bubbled through a one molar H+ ions as HCl solution at a temperature of 298⁰K. Under these conditions both hydrogen as well as hydrogen ions will be in their standard state and hence the name standard hydrogen electrode.  The platinum wire makes electrical contact and it is surrounded by an outer glass tube that has an inlet for hydrogen gas at the top and a number of holes at the base for the escape of hydrogen gas. It can act as a cathode as well as an anode depending on the potential of the electrode to which it is coupled.  If the potential of the coupled electrode is less than zero (Zn, Mg, Li) reduction takes place in SHE and it acts as the cathode. If the potential of the coupled electrode is greater than zero (Cu, Ag) oxidation takes place ...