Aqueous Reactions.ppt

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1、Aqueous Reactions,Dr. Ron Rusay Spring 2002,Aqueous Reactions,There are several general types:1) Precipitation: An insoluble salt forms from the addition of solutions. (Refer to Solubility Rules)2) Acid-Base Reactions (Neutralization) generally produces a salt plus water3) Oxidation-Reduction (Redox

2、) there is a change in oxidation numbers between reactants and products,Solution Test Apparatus for Electrolytes,Electrolytes,Aqueous solutions can be categorized into 3 types: non-electrolytes, strong electrolytes or weak electrolytes based on their ability to conduct electricity. A solution must h

3、ave ions to conduct. Pure Water does not conduct. Aqueous solutions can be tested for conductivity which will determine the degree of ionization of the solutes. It is possible to have full or partial ionization.,Electrolytes,Almost all ionic compounds and a few molecular compounds are strong electro

4、lytes. Several molecular compounds are weak conductors, most are non-conductors. Conductivity is directly related to the amount of ionization, i.e. ions in solution. Table salt, sodium chloride, is completely ionized:NaCl(s) + H2O(l) - NaCl(aq) - 0.10M Na +(aq) + Cl -(aq) 0.00M 0.10M 0.10M,Electroly

5、tes,Concentrations: CaCl2 (s) + H2O(l) - CaCl2(aq) - 0.10M Ca 2+(aq) + 2 Cl -(aq) 0.00M 0.10M 0.20M,Electrolytes,Sugars like sucrose are non-ionic, molecular compounds that dissolve but produce no ions. C12H22O11 (S) + H2O(l) - C12H22O11 (aq)Some molecular compounds like acetic acid ionize partially

6、 (dissociate) in water HC2H3O2 (l) + H2O(l) H3O+(aq)+ 0.1000M C2H3O2 -(aq) 0.9987M 0.0013M,Aqueous Bases,Any compound that accepts a proton is a base. The common bases are group IA & IIA metal hydroxide compounds. They are strong bases, dissociating completely in water. An example of a weak base is

7、ammonia. NH3 (g) + H2O(l) NH3 (aq) NH4+(aq)+ OH-(aq),Aqueous Reactions: Neutralization Net Ionic Equations,HCl(aq) + NaOH (aq) - NaCl (aq) + H2O(l)_ HCl(aq) - H+(aq) + Cl -(aq) NaOH (aq) - Na+(aq)+ OH-(aq) NaCl (aq) - Na+(aq)+ Cl-(aq)_Na+(aq)+ OH-(aq) + H+(aq) + Cl -(aq) - Na+(aq)+ Cl-(aq) + H2O(l)_

8、,H+(aq) + OH -(aq) - H2O(l),Aqueous Reactions: Precipitation Net Ionic Equations,50mL of a 0.1M solution of sodium sulfate is mixed with 50mL of a 0.2M solution of silver nitrate. What is the result? Molecular Equation:?Na2SO4(aq)+ ?AgNO3(aq) - ?Ag2SO4(s) + ?NaNO3(aq),1,2,1,2,Aqueous Reactions: Prec

9、ipitation Net Ionic Equations,Na2SO4(aq)+ 2 AgNO3(aq)Ag2SO4(s)+ 0.1M 0.2M 2 NaNO3(aq) Ionic Reaction (Reactants): Na2SO4(aq) 2 Na+(aq) + SO42-(aq)2 AgNO3(aq) 2 Ag+(aq) + 2 NO31-(aq)2 Na+(aq)+ SO42-(aq)+ 2 Ag+(aq)+ 2 NO31-(aq)0.2M 0.1M 0.2M 0.2M,Aqueous Reactions: Precipitation Net Ionic Equations,Na

10、2SO4(aq)+ 2 AgNO3(aq)Ag2SO4(s)+ 0.1M 0.2M 2 NaNO3(aq) Ionic Reaction (Products): 2 NaNO3(aq) 2 Na+(aq) + 2 NO31-(aq)Ag2SO4(s) Does not dissolve (ionize)2Na+(aq)+ 2NO31-(aq) + Ag2SO4(s)0.2M 0.2M solid,Aqueous Reactions: Precipitation Net Ionic Equations,Na2SO4(aq)+ 2 AgNO3(aq)Ag2SO4(s)+ 2 NaNO3(aq) Overall Ionic Reaction: 2Na+(aq)+ SO42-(aq) +2Ag+(aq)+ 2NO31-(aq) 2Na+(aq) + Ag2SO4(s) + 2NO31-(aq) Net Ionic Equation: (Subtract Spectator Ions),2Ag+(aq)+ SO42-(aq) Ag2SO4(s),= MNa2SO4 xVNa2SO4 / 1:1stoichiometry,= 0.10M x 0.050 L/ 1 = 0.0050 mol,How many moles?,