Types of Reaction

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Types of Reaction

  1. 1. • One system which is convenient at an introductory level involves classifying reactions into four basic types.• Knowing the different types of reaction allows the chemist to predict the products of the reactions of different substance.c
  2. 2. TYPES OF REACTIONS:1.COMBINATION REACTION2.DECOMPOSITON REACTION3.SUBSTITUTION REACTION4.DOUBLE REPLACEMENT REACTION
  3. 3. 1. COMBINATION REACTION • Type of reaction in which two or more substances combine to form a more complex substance. • Also called synthesis reaction • Form: A + B -> AB
  4. 4. EXAMPLES: • C ₍s₎ + O₂₍g₎ -> CO ₂₍g₎ • 2 Ca ₍s₎ + O ₂₍g₎ -> 2CaO ₍s₎ • N ₂₍g₎ + 3 H ₂₍g₎ -> 2NH ₃₍g₎ • 2 Na ₍s₎ + Cl ₂₍g₎ -> 2NaCl ₍s₎
  5. 5. 2. DECOMPOSITION REACTION Various conditions can cause a substance to decompose: • The most common type of a decomposition is cause by a rise in temperature. This is called thermal decomposition. Example: 2 HgO ₍s₎ ->(heat) 2Hg ₍g₎ + O ₂₍g₎ 2KMnO ₄₍s₎ ->(heat) K ₂MnO ₄₍s₎ + MnO ₂₍g₎ + O ₂₍g₎
  6. 6. • If such a decomposition proceeds very fast, an explosion may occurExample:2NH₄NO ₃₍s₎ ->(heat) 4H₂O ₍g₎ + 2N ₂₍g₎ + O ₂₍g₎
  7. 7. • Light is another factor which may occur chemical decompositions to occur. Such decompositions are known as photo-chemical decompositions.Example:2AgBr ₍s₎ ->(light) 2Ag ₍s₎ + Br ₂₍g₎
  8. 8. • Although catalysts cannot cause chemicals to decompose, they can speed up the rate of a chemical decomposition. The addition of a tiny amount of manganese dioxide to a solution of hydrogen peroxide will immediately result in a vigorous evolution of oxygen gas.Example:2H ₂O ₂₍aq₎ ->(manganese dioxide/catalyst)2 H ₂O ₍l₎ + O ₂₍g₎
  9. 9. • Electricity can also be used to decompose compounds, resulting in electrolytic decomposition.Examples:2NaCl ->(electrolysis) 2Na + Cl ₂PbBr ₂ ->(electrolysis) Pb + Br ₂
  10. 10. 3. SUBSTITUTION REACTION • Also called single replacement reaction • Form: C + AB -> CB + A • more active element replaces a less active element in the compound. Example: Fe + CuSO₄ -> FeSO₄ + Cu 2 Na + 2H₂O -> 2NaOH + H₂
  11. 11. Metals:Lithium(Li) Chromium(Cr) Mercury(Hg)Potassium (K) Iron(Fe) Platinum(Pt)Barium(Ba) Cobalt(Co) Gold(Au)Calcium(Ca) Nickel(Ni)Sodium(Na) Tin(Sn)Magnesium(Mg) Lead(Pb)Aluminum(Al) Hydrogen(H₂)Manganese(Mn) Copper(Cu)Zinc(Zn) Silver(Ag)
  12. 12. Halogens:Flourine(F)Chlorine(Cl)Bromine(Br)Iodine(I)
  13. 13. 4. DOUBLE REPLACEMENT REACTION • Also called ionic reaction • Characterized by the exchange of ions (charged atoms or molecules) between two compounds • Form: AB + CD -> AD + CB
  14. 14. Several types of double replacement reactions arefrequently encountered:1. A reaction between a base such as NaOH, KOH or Ca(OH)₂ in aqueous solution and an acid such as HCl, H₂SO₄ or CH₃COOH. Reactions of this type are called neutralizations and the products are always water molecules and salt.HCl + NaOH -> NaCl + H₂OH₂SO₄ + 2KOH -> K₂SO₄ + 2H₂O
  15. 15. 2. A reaction between solutions of two solublesalts, a soluble salt and an acid, or a solublesalt and an alkali which, by exchanging cationsand anions, can produce one insolublecompound.Examples:NaCl + AgNO₃ -> NaNO₃ + AgClBaCL₂ + MgSO₄ -> MgCl₂ + BaSO₄
  16. 16. Activity:Given the type of reaction, predict theproducts and balance the equation.1. Combination: Li + F₂2. Decomposition: CuCO₃3. Substitution: Mg + HCl4. Ionic reaction: AgNO₃ + BaCl₂
  17. 17. End …Thank you!

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