CLASS.X-CHEMICAL REACTIONS AND EQUATIONS-MODULE.4

TYPES OF CHEMICAL REACTION

•Combination Reaction
•Decomposition Reaction
•Displacement Reaction
•Double Displacement Reaction

COMBINATION REACTION • In combination reaction, two or more substances combine to form a new substance • For example – • C(s) + O₂ (g) CO₂ (g) • 2H₂ (g) + O₂ (g) 2H₂O (g)

DECOMPOSITION REACTION • In a decomposition reaction , a single compound breaks down to produce two or more similar substances. • The decomposition reactions take place when energy is supplied in the form of heat, electricity or light.

ELECTROLYSIS • When a substance is decomposed by passing electric current, the process is called electrolysis. • 2H₂O (I) 2H₂(g) + O₂(g)

THERMAL DECOMPOSITION • When a substance decomposes on heating it is called thermal decomposition. • CaCO₃ (S) CaO (S) + CO2 (g)

PHOTOCHEMICAL DECOMPOSITION • When a substance is decomposed in presence of sunlight, it is called a photochemical decomposition. • AgBr Ag +Br

REACTIVITY SERIES OF METALS • Reactivity series of metals is a series in which the metals arranged in the decreasing order of their reactivity.

DISPLACEMENT REACTION • In a displacement reaction, a more reactive metal displaces or removes another element from a compound. • For example • Zn(s) + CuSO4(aq) ZnSO4(s) +Cu In the above reaction Zn is more reactive Cu, so Zn displaces Cu from CuSO4. • 2AgNO₃ (aq) + Zn(s) → 2Ag(s) + Zn(NO3)2(aq) In the above reaction Zn is more reactive than Ag , so Zn displaces Ag from its solution.

DOUBLE DISPLACEMENT REACTION • The reaction in which two different atoms or group of atoms are displaced by other atoms or groups of atoms are double displacement reaction. • For example • BaCl₂(aq) + Na₂SO₄(aq) BaSO₄(s) + 2NaCl(aq) • Double displacement reaction can be

PRECIPITATION REACTION • Precipitation reactions occur when cations and anions in aqueous solution combine to form an insoluble ionic solid called a precipitate. • AgNO3 + NaCl AgCl + NaNO3

NEUTRALIZATION REACTION • A neutralization is a type of double replacement reaction. • In the reaction, H+ and OH- combine to form HOH or H2O or water molecules. • A salt is the product of an acid-base reaction. • For example • HCl + NaOH NaCl +H₂O In the above reaction NaCl is the salt.

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