#Cbse notes for class 10 plus#

Heat evolved during the reaction is written as + Heat on the product side.The formation of precipitate is indicated by a downward arrow.The evolution of gas is indicated by an upward arrow.To make a chemical equation more informative, the reaction conditions such as temperature, pressure or catalyst are written on the arrow separating the reactants and products.The molecular formulas are simply multiplied by suitable coefficients. While balancing a chemical equation, the molecular formulas of the reactants and products should not change.Then in that compound select the element which has the maximum number of atoms. We should always start balancing with the compound that contains maximum number of atoms.The first step in balancing a chemical equation is to write the number of atoms of each element present on the left hand side and right hand side.The process of equating the number of atoms on both the sides of a chemical equation is known as balancing of a chemical equation.As per the law of conservation of mass, the total mass of the elements present in the products of a chemical reaction is equal to the total mass of the elements present in the reactants.If heat is absorbed from the surroundings, then such a reaction is known as endothermic reaction. Exothermic and endothermic reactions: If heat is evolved during a reaction, then such a reaction is known as Exothermic reaction.Chemical change: If a change involves formation of new substances, it is a chemical change.Physical change: If a change involves change in colour or state but no new substance is formed, then it is a physical change.A chemical reaction can be observed with the help of any of the following observations:Evolution of a gas.During a chemical reaction, there is a breaking of bonds between atoms of the reacting molecules to give products.Substances that react or take part in the reaction are known as reactants and the ubstances formed are known as products. A chemical reaction involves a chemical change in which substances react to form new substances with entirely new properties.Oxidation of oils or fats in a flood, resulting into a bad smell and taste. Prevention:Painting, Galvanization, oiling greasing.Д¬orrosion of Aluminium has advantage, since Al2O3 formed as a result вћЈ Corrosion: Process of slowly reacting up of metals due to attack of atmospheric In a chemical reaction matter is conserved. Neutralisation Reaction : When an acid and a base react together to form salt Exothermic Reaction: Reaction in which heat is evolved.ДЎ0. Redox Reaction: Reaction involving both oxidation and reduction simultaneously CuO (s)+ H 2ДЁ. Reduction Reaction: In reduction Reaction addition of hydrogen or removal of oxygen or gain of electron takes place. Oxidation Reaction: In oxidation reaction, addition of oxygen or removal of hydrogen or loss of electron takes place. Double Displacement Reaction : Aqueous soln of two ionic compounds react by exchange of their ions is called double displacement Reaction BaCl 2 (aq) + Na 2SO 4 (aq)ДҐ. Displacement Reaction : A more reactive element displaces less reactive elemen from its aqueous salt soln Fe (s) + ZnSO 4 (aq) в†’Д¤. Decomposition Reaction : A single compound decomposes or break down to give two or moresimpler substances.ДЈ. Combination Reaction :Two or more reactant combine to form a single product.Дў. Balanced chemical equation: A balanced equation is a chemical equation in which number of atoms of each element is equal on both sides of the equation i.e number ofatoms of an element on reactant side = number of atoms of that element on the product side.ДЎ.Skeletal chemical equation: A chemical equation which simply represents the symbols and formulas of reactants and products taking part in the reaction is known as skeletal chemical equation for a reaction.ДЇor example: For the burning of Magnesium in the air, Mg + O 2 в†’ MgO is the skeletal equation. The arrow head points towards the products and indicates the direction of the reaction. An arrow separates the reactants from the products.

#Cbse notes for class 10 plus#

The products are written on the right hand side with a plus sign between them.The reactants are written on the left hand side with a plus sign between them.The symbolic representation of a chemical reaction is called a вЂ“ Reactants lose their properties to form product of different properties. вЂ“ Old bonds are broken, new bonds are formed. вЂ“ Atoms in the reactants are rearranged to form one or more different substances. вћЈ Physical Change: Change in physical properties. Chapter 1 Chemical Reactions and EquationsД¬BSE Notes for Class 10 Science Chemistry