Chemical Reaction

1. Chemical Reaction By iTutor.com T- 1-855-694-8886 Email- [email protected]

2. Chemical Reaction A chemical reaction occurs when one or more chemicals react to become different chemicals. A chemical reaction is characterized by the re-arrangement of atoms from the reactant side of the equation to the product side. -: Example :- Hydrogen gas burns in oxygen to make water. 2H 2 + O 2 2H 2 O

3. Types of Chemical Reaction Decomposition Reactions Combination R eactions Single-Replacement Reactions Double-Replacement Reactions Combustion Reactions

4. Decomposition Reaction A  decomposition reaction  is a reaction in which a single compound decomposes to two or more other substances . AB A + B Where A and B can be elements or compounds . Most compounds can be broken down into simpler substances or decomposed.

5. Decomposition Reaction -: Example :- The industrial preparation of calcium oxide (Lime) involves the decomposition of calcium carbonate by heating it. CaCO 3 (s) CaO(s) + CO 2 (g)

6. Combination Reaction A  combination reaction  is a reaction in which two substances combine to form a third . A + B AB Where A and B can be elements or compounds. Decomposition and combination reactions can be considered to be the reverse of each other.

7. Combination Reaction -: Example :- The reaction of calcium oxide with sulfur dioxide to form calcium sulfite CaO(s) + SO2(g) CaSO3(s)

8. Single-Replacement Reaction A  single-replacement reaction  is a reaction in which an element reacts with a compound and replaces another element in the compound . A + BC AB + C Where A and C are elements and BC and AB are compounds.

9. Single-Replacement Reaction -: Example :- The reaction in which copper displaces silver from an aqueous solution of silver nitrate Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

10. Double-Replacement Reaction A  double-replacement reaction is a reaction in which there is an exchange of positive ions between two compounds. These reactions generally take place between two ionic compounds in aqueous solution. AB + CD AD + CB Where A and C are cations and B and D are anions . For a double-replacement reaction to occur, at least one of the products must be a gas or water, or a precipitate .

11. Double-Replacement Reaction -: Example :- Precipitation reactions are one type of double- replacement reaction. AgNO 3 ( aq ) + NaCl( aq ) AgCl(s) + NaNO 3 ( aq )

12. Combustion Reaction A  combustion reaction  is a reaction in which a substance reacts with oxygen, usually with the fast release of heat and the production of a flame. Organic compounds usually burn in the oxygen in air to produce carbon dioxide and if the compound contains hydrogen, another product will be water.   For example butane burns in air as follows.

13. Combustion Reaction -: Example :- In general: C x H y + O2 CO2 + H2O Products in combustion are ALWAYS carbon dioxide And water. Combustion is used to heat homes and run automobiles (octane, as in gasoline, is C8H18).

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