The document classifies different types of chemical reactions: 1) Synthesis reactions involve combining two or more reactants to form one product. 2) Decomposition reactions involve breaking down one reactant into two or more products. 3) Single displacement reactions involve one compound exchanging ions with another. 4) Double displacement reactions involve two compounds exchanging ions to form two new compounds.

1. Classification of Reactions

2. Classification All reactions can be placed into groups. Look for “tell tale” signs in the reaction.

3. 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

4. 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

5. 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

6. 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.

7. 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.

8. 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

9. 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.

10. 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

11. Classification continued All reactions fit one of the categories. AND Some reactions fit more than one.

12. 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

13. 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