Determining Products of Reactions AP Chemistry 2012-2013 Chemical Reactions Determining Products of Reactions AP Chemistry 2012-2013

Types of Reactions Metathesis – no transfer of electrons Double Replacement Precipitation Reactions Solids Gases Acid-Base Reactions

Types of Reactions Continued Oxidation-Reduction Reactions – transfer of electrons Some types of redox reactions include Single Replacement Combustion Synthesis Decomposition

Writing the equations NET IONIC ONLY Balanced for mass and charge Examples

Two Elements as Reactants Synthesis Be sure to assign the most common oxidation states to the elements Examples Solid zinc is heated in chlorine gas. Solid sulfur is burned in oxygen

Example Reactions Answers Zn + Cl2  ZnCl2 S + O2  SO2

Single Reactant Must be a Decomposition When unsure, break the compound into its elements Most do not completely decompose but produce Ionic salts and oxide gases Example Solid calcium carbonate is heated A piece of solid potassium nitrate is heated

Example Reactions Answers CaCO3  CaO + CO2 2 KNO3  2 KNO2 + O2

Water is a Reactant Three variations Pure metal or metal hydride in water makes a base and hydrogen gas. Sodium metal is added to distilled water Lithium hydride is added to distilled water A metal oxide in water will produce a base. Solid barium oxide is added to water. A nonmetal oxide in water will produce an acid. Solid dinitrogen pentoxide is added to water. Carbon dioxide gas is bubbled through water.

Examples Answers Na + 2 H2O  Na+ + 2 OH- + H2 LiH + 2 H2O  Li+ + 2 OH- + H2 BaO + H2O  Ba2+ + 2 OH- N2O5 + H2O  2 H+ + 2 NO3- CO2 + H2O  H2CO3

Mixture of two salt solutions Precipitation Reactions – KNOW YOUR SOLUBILITY RULES AND COMMON IONS Net ionic and balanced Examples A solution of silver nitrate is added to a solution of potassium iodide Solutions of lead(II) nitrate and tri-potassium phosphate are mixed

Examples Ag+ + I-  AgI 3 Pb2+ + 2 PO4 3-  Pb3(PO4)2

Combustion of carbon compounds Combustion is the reaction with oxygen Produces carbon dioxide and water when enough oxygen is present Examples Propane is burned in air. Carbon disulfide is burned in excess oxygen.

Examples C3H8 + 5 O2  3 CO2 + 4 H2O CS2 + 3 O2  CO2 + 2 SO2

Single replacement Transition metal placed in a solution Oxidation-reduction reaction Metal will always be oxidized M+x Neutral conditions Ion in solution will be reduced Examples Solid manganese flakes are placed in a solution of copper (II) sulfate Iron filings are placed in a solution of iron (III) sulfate.

Examples Mn + Cu2+  Mn2+ + Cu Fe + 2 Fe3+  3 Fe 2+ Fe  Fe 2+ + 2e- Fe 3+ + 1 e-  Fe 2+

Single replacement (2) Acidic conditions with an oxoacid Examples Anion of the oxoacid will be reduced to an oxide gas and water will form Examples Copper is immersed in dilute nitric acid Lead is immersed in concentrated warm sulfuric acid

Examples Cu + H+ + NO3-  Cu2+ + NO + H2O Pb + H+ + HSO4-2  Pb2+ + SO2 + H2O

Formation of complex ions Look for transition metal ions in solution with NH3, OH-, CN-, or SCN- Don’t worry about how many you put on the metal ion Usually combine in 1, 2, 4, or 6 Add the charges together to determine the charge on the whole ion Example Excess ammonia is added to a solution of silver nitrate Ag+ + NH3  Ag(NH3)2+

More examples of complex ions A solution of sodium cyanide is added to a solution of iron(II) chloride Fe 2+ + CN-  Fe(CN)6 4- Charges are determined by adding all the ions in the complex 2+ + 6 x -1 = -4

Videos of reactions – alkali metals and water http://www.youtube.com/watch?v=oqMN3y8 k9So http://www.youtube.com/watch?v=Jy1DC6E uqj4 http://www.youtube.com/watch?v=92Mfric7 JUc