Reaction Types

Five Types of Chemical Rx’s Double Replacement AX + BY → AY + BX Single Replacement AX + B → BX + A AX + Y2 → AY + X2 Synthesis C + D → CD Decomposition CD → C + D Combustion RS + O2 → RO + SO 2

What is the “driving force” makes chemical reactions happen? There are several: Formation of a gas. Formation of a molecular compound. Formation of a precipitate from aqueous solutions. Movement of electrons - Redox Reactions 3

Combination (Synthesis) Reactions Two or more substances combine to form a new compound. A + X  AX Reaction of elements with oxygen and sulfur Reactions of metals with Halogens Synthesis Reactions with Oxides There are others not covered here!

Decomposition Reactions A single compound undergoes a reaction that produces two or more simpler substances AX  A + X Decomposition of: Binary compounds H2O(l )  2H2(g) + O2(g) Metal carbonates CaCO3(s)  CaO(s) + CO2(g) Metal hydroxides Ca(OH)2(s)  CaO(s) + H2O(g) Metal chlorates 2KClO3(s)  2KCl(s) + 3O2(g) Oxyacids H2CO3(aq)  CO2(g) + H2O(l )

Single Replacement Reactions A + BX  AX + B BX + Y  BY + X Replacement of: Metals by another metal Hydrogen in water by a metal Hydrogen in an acid by a metal Halogens by more active halogens

The Activity Series of the Metals Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Chromium Iron Nickel Lead Hydrogen Bismuth Copper Mercury Silver Platinum Gold Metals can replace other metals provided that they are above the metal that they are trying to replace Metals above hydrogen can replace hydrogen in acids. Metals from sodium upward can replace hydrogen in water

The Activity Series of the Halogens Halogens can replace other halogens in compounds, provided that they are above the halogen that they are trying to replace. Fluorine Chlorine Bromine Iodine 2NaCl(s) + F2(g)  2NaF(s) + Cl2(g) MgCl2(s) + Br2(g)  No Reaction

Double Replacement Reactions The ions of two compounds exchange places in an aqueous solution to form two new compounds. AX + BY  AY + BX One of the compounds formed is usually a precipitate, an insoluble gas that bubbles out of solution, or a molecular compound, usually water.

Combustion Reactions A substance combines with oxygen, releasing a large amount of energy in the form of light and heat. Reactive elements combine with oxygen P4(s) + 5O2(g)  P4O10(s) (This is also a synthesis reaction) The burning of natural gas, wood, gasoline C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g)