AQUEOUS REACTIONS
 A solution is a homogeneous mixture of two or more
substances.
 All aqueous solutions can be classified in terms their
ability to conduct electricity.
 If a substance forms ions in solution, it is an electrolyte
and will conduct electricity. Ie. NaCl
 If a substance does not form ions in solution, it is a
nonelectrolyte and does not conduct electricity.Ie. sugar
 Compounds whose aqueous solutions conduct electricity
well are strong electrolytes. Compounds whose solutions
conduct electricity poorly are weak electrolytes.
 Exchange (metathesis) reactions involve the exchange of
ions in solution.
 Ionic equations:
2KI(aq)+Pb(NO3)2(aq)PbI2(s)+2KNO3(aq)
 Both potassium iodide and lead nitrate are colorless
solutions. When mixed they form lead iodide, a yellow
precipitate.
 The molecular equation lists all species in their molecular
form
 The complete ionic equation lists all strong soluble
electrolytes as ions:Pb2+(aq)+2NO3-(aq)+2K+(aq)+2I(aq)PbI2(s)+2K+(aq)+2NO3-(aq)
 The net ionic equation lists only those ions not common
on both sides of the reaction:Pb2+(aq)+2I-(aq)PbI2(s)
 The spectator ions that are present in the solution , but
play no direct role in the reaction are eliminated in the
net equation.
 Acids are substances that ionize in aqueous solutions to
form H+. Acids are proton donors. Bases are proton
acceptors. Bases react with the H+ to form water.
 Strong acids and bases are strong electrolytes. They
ionize completely in solution.
 Strong bases include Group1A metal hydroxides,
Ca(OH)2, Ba(OH)2, and Sr(OH)2
 Strong acids include HCl, HBr, HI, HClO3, H2SO4, and
HNO3
 Weak acids and weak bases are weak electrolytes. They
partially ionize in solution.
 A neutralization reaction occurs when an acid and base
react. The result is the formation of a salt and water
 Acids react with carbonates and hydrogen carbonates to
form carbon dioxide and water
 H+(aq)+ HCO3-(aq)H2O(l)+CO2(g)
 Reaction of sulfides with acid generate hydrogen sulfide
 2H+(aq)+S2+(aq)H2S(g)
 When a substance loses electrons, it undergoes
oxidation(OIL): Ca(s)+2H+(aq)Ca2+(aq)+H2(g).
 When a substance gains electrons, it undergoes
reduction(RIG): 2Ca(s)+O2(g)2CaO(s)
 The reaction of a metal with an acid or a metal salt is
called a displacement reaction: A+BXAX+B
 It is common for metals to produce hydrogen gas when
they react with acids.
 Mg(s)+2HClMgCl2(aq)+H2(g) molecular
 Mg(s)+2H+Mg2+(aq)+ H2(g) net ionic
 The metal is oxidized and the H+is reduced.
 It is possible for metals to be oxidized in the presence of a
salt:Fe(s)+Ni(NO3)2(aq)Fe(NO3)2(aq)+Ni(s) molecular
 Fe(s)+ Ni2+(aq)Fe2+(aq)+Ni(s) net ionic
 In this case, iron is oxidized and nickel is reduced.
 If one substance is oxidized, another substance must be
reduced.
 Molarity=moles of solute/liters of solution
 When an ionic compound dissolves, the relative
concentration of ions depends on the chemical formula
 For 1M NaCl, the solution is 1M in Na+ ; 1M in Cl For 1M Na2SO4, the solution is 2M in Na+; 1M in SO4 When making dilutions, MinitialVinitial=MfinalVfinal