Classification <ul><li>All reactions can be placed into groups. </li></ul><ul><li>Look for “tell tale” signs in the reaction. </li></ul>
Synthesis reactions A given compound is formed from simpler materials A + B AB Na + Cl 2 NaCl Indicators are: Two or more reactants One product
Decomposition reaction Breaking a compound down into simpler compounds AB A + B H 2 O H 2 + O 2 Indicators are: One reactant 2 or more products
Single Displacement reaction 1 compound exchanges either a cation or anion with another AB + C AC + B Mg + HCl MgCl 2 + H 2 Indicators are: Element + compound yields element +compound
Double Displacement reactions 2 compounds exchange cations and anions with one another AB + CD CB + AD AgNO 3 + NaCl NaNO 3 + AgCl Indicators are: Usually all the species are compounds.
Precipitation reactions When a solid forms from a chemical reaction Pb(NO 3 ) 2 (aq) + KI (aq) PbI 2 (s) + KNO 3 (aq) The indicator is a solid on the product side but not on the reactant side.
Acid/Base reaction HCl (aq) + NaOH (aq) H 2 O (l) + NaCl (aq) The indicators are: Acid, H in the front Base, OH in the back Water as a product. when water and a salt are formed from the reaction of an acid with a base
Oxidation/Reduction reactions involves a transfer of electrons Mg (s) + O 2 (g) MgO (s) look at charges 0 0 +2 -2 Magnesium lost two electrons oxidized Oxygen gained two electrons reduced Indicators are: Element by itself on one side & in a compound on the other.
Combustion reaction burning of a compound CH 4 + O 2 CO 2 + H 2 O Indicators are: Oxygen as a reactant CO 2 or H 2 O or both as a product
Classification continued <ul><li>All reactions fit one of the categories. </li></ul><ul><li>AND </li></ul><ul><li>Some reactions fit more than one. </li></ul>
Sample Problems NH 3 (g) + H 2 SO 4 (aq) (NH 4 ) 2 SO 4 (aq) synthesis H 2 O 2 (aq) H 2 O(l) + O 2 (g) decomposition redox Al(s) + H 3 PO 4 (aq) H 2 (g) + AlPO 4 (aq) single displacement redox
C 3 H 7 CHO(l) + O 2 (g) CO 2 (g) + H 2 O(g) combustion redox NH 4 OH(aq) + HNO 3 (aq) H 2 O(l) + NH 4 NO 3 (aq) acid/base double displacement Pb(NO 3 ) 2 (aq) + KCl(aq) PbCl 2 (s) + KNO 3 (aq) double displacement precipitation