D. C. Pant 💻

  Corrosion         It is the slow process of eating away metals by the reaction of atmospheric air and moisture, e.g. rusting of iron, formation of green coating over copper etc. PREVENTION OF CORROSION      Rusting of iron is prevented by galvanising, by making alloys, painting, greasing or oiling and tin-plating and chrome plating . Explained below -- 1. Galvanisation - It is the process of coating iron and steel object with a thin layer of zinc. It is done by dipping the object in molten zinc. The galvanised article is protected against rusting even if the zinc coating is broken. 2. Alloying - It is the method of improving the properties of a metal by mixing the metal with another metal or non-metal. 3. Alloying of iron - Pure iron is very soft and stretches easilywhen hot. It is mixed with a small amount of carbon and it becomes hard and strong. Iron is mixed with many metals to form different types of alloys. For example, when iron is mix...

  Types of chemical reaction The chemical reaction are classified into different classes depending upon the type of chemocal changes taking place. These reactions are as follows :   1.   Combination Reaction :-           A reaction in which two or more reactants combine to form a single product, is called combination reaction, e.g.   CaO (s) + H 2 O (l) → Ca(OH) 2(aq) + Heat   C (s) + O 2(g)     →    CO 2(g)   2.   Decomposition Reaction :-           A reaction in which a single reactants breaks down to form two or more products, is known as decomposition reaction. This reaction is opposite to combination reaction. e.g. CaCO 3(s)   →   CaO (s)   +   CO 2(g)   2AgCl (s)   →   2Ag (s) +   Cl 2(g)   2NaCl (l)   →   2Na (s)   +   Cl 2(g)   ...

  Balanced chemical equation             A balanced chemical equation is that in which the total number of atoms of each element are equal on both sides of the equation. The balancing of a chemical equation is based on law of conservation of mass. According to this – “mass can neither be created nor be destroyed during a chemical reaction.”               The method used for balancing chemical reaction is called hit and trial method as we make trials to balance the equation by using the smallest whole number coefficient. In this method the number of atoms of each element remains the same, before and after a chemical reaction.   BALANCING A CHEMICAL EQUATION             Several steps are involved in balancing a chemical equation. These steps are as follows :- Step (a) Writing unbalanced equation an...

Chemical Reactions A chemical reaction is a change in which one or more substances or reactants reacts to to form new substances with different properties. The reacting species (molecule, atom or ion) are known as reactants (the substances that undergo chemical change in the chemical reaction) and the new species formed as a result of the reaction are called products (the new substances formed during reaction).   2Na (s) + 2H 2 O (l) → 2NaOH (aq) + H 2(g) ↑ In the above chemical reaction , sodium hydroxide and hydrogen are the products and sodium and water are the reactants.     Identification of chemical reaction A chemical reaction can be identified by either of the following observations – (i)                 Change in state (ii)              Change in colour (iii)            Evolutio...