Reactions in Aqueous Solutions

Reactions When you mix 2 aqueous ionic compounds, there are 2 possible outcomes: 1) compounds will remain in solution without reacting AB + CD  NR (no reaction) 2) you can have a double displacement reaction (DD) WX + YZ  WZ + YX

Evidence? How do you recognize if DD has occurred? precipitate (ppt) forms gas forms water forms

A. Formation of a Precipitate ions are removed by the formation of an insoluble solid need to use solubility guidelines Examples: 1) Pb(NO3)2(aq) +2NaI(aq)  2NaNO3(aq) + PbI2(s) a) see solubility guidelines: NaNO3 is soluble and PbI2 is insoluble

A. Formation of a Precipitate Examples: 2) The reaction of: potassium carbonate sol’n and copper (II) sulfate sol’n see solubility guidelines to find if a product is insoluble write word equation for the reaction write balanced chemical equation write total ionic equation (TIE) write net ionic equation (NIE) to show reacting ions only identify the reacting ions identify the spectator ions (the ions that remain on each side of the eq’n)

A. Formation of a Precipitate Examples: 3) NaNO3(aq) + CuSO4(aq)  ? see solubility guidelines to find if a product is insoluble

B. Formation of a Gas ions are removed from the solution in the form of a gaseous product gases are commonly H2(g), H2S(g), SO2(g), CO2(g), and NH3(g). often the result of molecular compounds (nonmetal-nonmetal) involved in the rxn

B. Formation of a Gas Na2SO3(aq) + 2HCl(aq)  2NaCl(aq) + H2SO3(aq) Examples: 1) hydrogen gas LiH(s) + H2O(l)  LiOH(aq) + H2(g) 2) sulfur dioxide gas Na2SO3(aq) + 2HCl(aq)  2NaCl(aq) + H2SO3(aq)   H2SO3(aq)  SO2(g) + H2O(l) Net rxn: Na2SO3(aq) + 2HCl(aq)  2NaCl(aq) + SO2(g) + H2O(l) 3) For other gases, see p340

C. Formation of Water H+ and OH- ions are removed from solution as water also called neutralization reaction between acid and base forms water and a salt

C. Formation of Water Examples HCl(aq) + KOH(aq)  H2SO4(aq) + NaOH(aq)  HNO3(aq) + MgO(s)  LiOH(s) + CO2(g) 

C. Formation of Water Examples HCl(aq) + KOH(aq)  KCl(aq) + H2O(l) H2SO4(aq) +2 NaOH(aq)  K2SO4(aq) + 2H2O(l) 2 HNO3(aq) + MgO(s)  Mg(NO3)2(aq) + H2O(l) 2 LiOH(s) + CO2(g)  Li2CO3 (aq) + H2O(l) NOTE: NIE is always the same for neutralization reaction (rxn #1 and #2)!