🗊Презентация Chem reactions. Different Typesof Chemical Reactions

A Presentation on “Different Types of Chemical Reactions” By Utkarsh Singh India

Chemical changes The formation of new substances takes place with different chemical properties is called chemical changes. A chemical change can be confirmed by any or all of the following observations: change in state change in color change in temperature evolution of gas

What is Chemical Reaction? The change of one or more substances into other substances having different composition and properties is called a chemical reaction. C(s) + O2(g) CO2(g) 2H2(g) + O2(g) 2H2O(g)

Combination reactions Combination reactions Decomposition reactions Displacement reactions Double-displacement reactions Oxidation-reduction reactions Precipitation reactions Exothermic and endothermic reactions

What is combination reaction? A reaction in which two or more substances (elements or compounds) combine together to form a new substance is called a combination reaction. Many combustion reaction are also examples of combination reaction. where A,B,C and ABC represent elements or compounds

Examples: Examples: H2(g) + Cl2(g) 2HCl(l) Mg(s) + Cl2(g) MgCl2(s) Fe(s) + S(s) FeS (s) MgO(s) + H2O(l) Mg(OH)2 (aq)

Synthesis Reaction: Synthesis Reaction: The combination reaction in which a compound is formed from its constituent elements is called “synthesis reaction”.

What is decomposition reaction? What is decomposition reaction? A reaction in which a substance is broken down into two or more simpler substances is known as decomposition reaction. A decomposition reaction is opposite of combination. A decomposition reaction takes place only when some energy in form of heat, light or electricity is supplied to the reactant.

Various types of decomposition reactions Thermal decomposition reaction Decomposition caused by heating Electrolytic decomposition (electrolysis) reaction Decomposition reaction caused by electricity Photodecomposition reaction Decomposition reaction caused by light

Examples: Examples: ZnCO3(g) ZnO(s) + CO2(g) 2H2O (l) 2H2(g) + O2(g) CaCO3(s) CaO (s) + CO2 (g) 2H2O2(l) 2H2O(l) + O2(g)

What is displacement reaction? What is displacement reaction? A reaction in which one part (an atom or a group of atoms) of a molecule is replaced by another is called a displacement reaction.

Examples: Examples: Zn(s) + 2HCl(dil) ZnCl2(aq) + H2(g) 2KBr(aq) + Cl2(aq) 2KCl(aq) + Br2(aq) CuSO4(aq) + Zn(s) Cu(s) + ZnSO4(aq) Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)

What is double-displacement reaction? What is double-displacement reaction? A reaction in which the two reacting ionic compounds exchange their corresponding ions is called a double-displacement reaction.

Examples: Examples: AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) Ni(NO3)2 (aq) + 2NaOH (aq) Ni(OH)2(s) + NaNO3(aq) 2KBr(aq) + BaI2 (aq) 2KI(aq) + BaBr(aq) Pb(CH3COOH)2(aq) +2HCl(aq) PbCl2(s) + CH3COOH(aq)

What do you mean by oxidation-reduction reaction? What do you mean by oxidation-reduction reaction? Oxidation reaction: any process involving addition of oxygen, removal of hydrogen and/or loss of electron is known as oxidation reaction. Example: Addition of oxygen P4(s) + 5O2(g) 2P2O5(s) (oxidation of P4) Removal of hydrogen H2S(aq) + Br2(aq) 2HBr(aq) + S(s) (oxidation of H2S) Loss of electron Al (s) Al3+(aq) + 3e- (oxidation of Al)

Oxidising agent : The substance which brings about oxidation of other substances is called an oxidising agent. Oxidising agent : The substance which brings about oxidation of other substances is called an oxidising agent. Example: 1. KMnO4 (potassium permanganate) 2 .H2SO4 (conc. sulphuric acid) Reduction reaction: any process involving removal of oxygen, addition of hydrogen and/or gain of electron is known as reduction reaction. Example: Removal of oxygen Fe2O3(s) + 3CO(g) Fe(s) + 3CO2(g) (reduction of Fe2O3) Addition of hydrogen H2S(aq) + Cl2(g) 2HCl(aq) + S(s) (reduction of Cl) Gain of electron Cu2+(aq) + 2e- Cu(s) (reduction of Cu2+)

Reducing agent: The substance which brings about reduction of other substance is called a reducing agent. Reducing agent: The substance which brings about reduction of other substance is called a reducing agent. Example: 1. H2 (hydrogen) 2.SO2 (sulphur dioxide)

What is precipitation reaction? What is precipitation reaction? The reaction in which one of the products formed is an insoluble substance and is thrown out of the solution as a solid (called precipitate) is called precipitation reaction. The formed precipitate is indicated by a downward arrow( ).

Examples: Examples: AgNO3(aq) + KCl(aq) AgCl(s) + KNO3(aq) Pb(NO3)2 (aq) + 2KI(aq) PbI2(s) + 2KNO3(aq) BaCl2(aq) + Na2SO4(aq) BaSO4(s) + 2NaCl(aq) LiBr(aq) + AgNO3(aq) LiNO3(aq) + AgBr(s)

What do you mean by exothermic and endothermic reaction? What do you mean by exothermic and endothermic reaction? Reaction which is accompanied by evolution of heat is known as exothermic reaction whereas reaction accompanied by absorption of heat is known as endothermic reaction. Melting of ice is an endothermic reaction Freezing of water is an exothermic reaction Exothermic and endothermic are reverse of each other.

Example: Example: H2O(s) + heat H2O(l) (endothermic) C(s) + H2O(v) + heat CO(g) + H2(g) (endothermic) CH4(g) + 2O2(g) CO2(g) + 2H2O(g) + heat (exothermic) H2(g) + O2(g) H2O(g) + heat (exothermic)