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Oxidation-Reduction Reactions. Predicting Products of Reactions AP Chemistry Ms. Paskowski. Single Replacement Reactions. More reactive element will replace a less reactive element Metals – use the activity series or the Standard reduction tables Nonmetals – use the activity table (easier).
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Oxidation-Reduction Reactions Predicting Products of Reactions AP Chemistry Ms. Paskowski
Single Replacement Reactions More reactive element will replace a less reactive element Metals – use the activity series or the Standard reduction tables Nonmetals – use the activity table (easier)
Single Replacement Reactions of Metals • The more reactive metal will replace the less reactive metal within a compound • Example • Zn (s) + CuSO4 Cu (s) + ZnSO4 • The more reactive zinc replaces copper.
Single Replacement Reactions Standard reduction potentials • All reactions listed are reduction reactions. • The reactions most likely to occur have the largest positive value. • The more positive, the more likely to be reduced
Predicting Products of Single Replacement Reactions • M + AB or N + CD • where M = metal and N = Nonmetal • Use Activity table to determine whether • M is more active than A or less likely to be reduced, if so a reaction will occur. • N is more active than D or more likely to be reduced, if so a reaction will occur
Practice Problems • Chemistry: Matter and Its Changes • Page 224 #5.50 and 5.51
Elements with Water • Very active metals will combine with water to form bases • Hydroxides • Often produce hydrogen gas • Very Reactive Nonmetals will react with water to form acids • Conditions will dictate which acid is formed.
Oxidizing Power of Acids • Nonoxidizing acids– i.e. HCl, HBr • Hydrogen will be replaced by a more active metal. H will be reduced and the metal will be oxidized. Anion does not participate • Oxidizing Acids always contain oxygen. • Anion is sometimes a stronger oxidizer than H+ • i.e. HNO3, H2SO4 (under certain conditions)
Reactions of Metals with Acids • Acids will react with active metals • Using the Standard Reduction Potential table • If the reduction value is negative , the metal will replace the H in the acid and Hydrogen gas will be produced. • If the reduction value is positive, no reaction will occur.
Predicting Products of the Metal/Acid Reactions • For anoxy acids, the products are a salt and hydrogen gas • M + HA MA + H2 • For oxoacids, the products are a salt, water, and a gas • M + HAxOy H2O + M+ + AzOq • Practice Problems • Page 224 # 46-49
Molecular Oxygen • Oxidizer! • Combustion is the adding of oxygen to carbon and hydrogen (and sulfur and nitrogen). • Reaction with metals form oxides • Reaction with nonmetals produce nonmetallic oxides
Oxides and Water • Soluble Metallic oxides • MxOy produce bases (hydroxides) when dissolved in water • Example • NaOH + H2O Na+ + OH- • Nonmetallic oxides • Produce acids when dissolved in water • Example • N2O5 + H2O H+ + NO3 –
Oxides and Acids or Bases • Metallic oxides plus acid • Produce a salt and water • Metallic oxides are weak bases and will react with the acid to produce salt and water • Nonmetallic oxides plus bases • Nonmetallic oxides are acidic • Produce a salt and water • Nonmetallic oxides are weak acids and will react with the base to produce salt and water
Metallic Oxides and Nonmetallic Oxides • Metallic oxides and nonmetallic oxides will combine to form a salt • Example • MgO + CO2 MgCO3 • CaO + SO3 CaSO4
Synthesis Reactions • Metals plus nonmetals • Adding Hydrogen makes hydrides • Adding halogens makes halides • Adding nitrogen makes nitrides • Adding sulfur makes sulfides • Adding oxygen makes oxides • Adding LOTS of oxygen makes peroxides • Adding water makes hydroxides or oxides and hydrogen gas
Decomposition • Problems given will usually produce a oxygen or water • Examples • CaCO3 CaO + CO2 • H2O2 H2O + O2 • KClO3 KCl + O2 • Al(OH)3 Al2O3 + H2O
Helpful Hints • Write all the species down in their physical state, i.e. liquid, solid, gas, or ions in solution • Determine the type of reaction that could occur • Double replacement – acid/base or precipitate • Oxidation-Reduction – single replacement, combustion, decomposition (only one reactant), synthesis • If nothing else fits, use a simple redox reaction where the charges on the ions change.
