aqueous reactions dr. ron rusay. aqueous reactions there are several general types: 1)...
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Aqueous Reactions
Dr. Ron Rusay
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 water
3) Oxidation-Reduction (Redox) there is a change in oxidation numbers between reactants and products
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Solution Test Apparatusfor 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 have 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.
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Electrolytes Almost all ionic compounds and a few molecular
compounds are strong electrolytes. 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
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Molarity (M) = Moles solute / Liter solution
Electrolytes
Concentrations: CaCl2 (s) + H2O(l) CaCl2(aq) 0.10M
Ca 2+
(aq) + 2 Cl -(aq) 0.00M
0.10M 0.20M
Molarity (M) = Moles solute / Liter solution
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 (dissociate) in water
HC2H3O2 (l) + H2O(l) H3O+(aq)+
0.1000M C2H3O2 -(aq)
0.9987M 0.0013M
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Molarity (M) = Moles solute / Liter solution
Aqueous Acids
Any compound that provides a proton can be considered an acid. Strong acids are sulfuric acid, nitric acid, perchloric acid, HI, HBr and HCl.
Electrolytes
How would the conductivity of acetic acid compare to hydrochloric acid?
HCl Completely Ionized
Acetic Acid (HC2H3O2)
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 ammonia.
NH3 (g) + H2O(l) NH3 (aq) NH4+
(aq)+ OH-(aq)
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⇔ ⇔
An Aqueous Solution of Sodium Hydroxide
NH3 in Water
QUESTION
Aqueous Reactions: Neutralization
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) _______________________________________________________
H+(aq) + OH -
(aq) H2O(l)
An aqueous solution of H2SO4 is added to aqueous Ba(OH)2. The reaction is monitored using a conductivity tester. Predict the correct statement(s).
I) Both H2SO4 and Ba(OH)2 are strong electrolytes.
II) This is a neutralization reaction.
III) This is a precipitation reaction.
IV) The light bulb will glow at the neutralization point.
A) II B) I and II
C) I, II and III D) I, II, III and IV
QUESTION
Aqueous Reactions: Acid-Base
QUESTIONIf an antacid contains Al(OH)3 it will form AlCl3 upon neutralization of stomach acid. How many moles of Cl– ions are in 100.0 mL of 0.010 M AlCl3?
A.0.0010 MB.0.010 MC.0.0030 MD.0.030 M
Molarity (M) = Moles solute / Liter solution
QUESTION
How do you know the state of the products?
What type of reaction is it?
Write a balanced equation for the reaction.
QUESTIONGiven the insoluble compound Al2(CO3)3 predict the ions and coefficients that would be necessary to complete the following net ionic equation:
__ _____ + ____ _____ Al2(CO3)3
A.2 AlCl3 + 3 Na2CO3 also include 6 NaCl on rightB.3 Al3+ + 2 CO3
2–
C.2 Al3+ + 3 CO32–
D.2 Al3+ 6 Cl – + 3 CO32– + 6 Na+
Aqueous Reactions: PrecipitationNet 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)
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1 2
1 2
Aqueous Reactions: PrecipitationNet Ionic Equations
Na2SO4(aq)+ 2 AgNO3(aq) Ag2SO4(s)+ 2 NaNO3(aq)
0.1M 0.2M Ionic Reaction (Reactants):
Na2SO4(aq) 2 Na+(aq) + SO4
2-(aq)
2 AgNO3(aq) 2 Ag+(aq) + 2 NO3
1-(aq)
2 Na+(aq)+ SO4
2-(aq)+ 2 Ag+
(aq)+ 2 NO31-
(aq)
0.2M 0.1M 0.2M 0.2M
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Aqueous Reactions: PrecipitationNet Ionic Equations
Na2SO4(aq)+ 2 AgNO3(aq) Ag2SO4(s)+ 2 NaNO3(aq)
0.1M 0.2M Ionic Reaction (Products):
2 NaNO3(aq) 2 Na+(aq) + 2 NO3
1-(aq)
Ag2SO4(s) Does not dissolve (ionize)
2Na+(aq)+ 2NO3
1-(aq) + Ag2SO4(s)
0.2M 0.2M solid
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Aqueous Reactions: PrecipitationNet Ionic Equations
Na2SO4(aq)+ 2 AgNO3(aq) Ag2SO4(s)+ 2 NaNO3(aq)
Overall Ionic Reaction:
2Na+(aq)+ SO4
2-(aq) +2Ag+
(aq)+ 2NO31-
(aq)
2Na+(aq) + Ag2SO4(s) + 2NO3
1-(aq)
Net Ionic Equation: (Subtract Spectator Ions)
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2Ag+(aq)+ SO4
2-(aq) Ag2SO4(s)
= MNa2SO4 xVNa2SO4 / 1:1stoichiometry
= 0.10M x 0.050 L/ 1= 0.0050 mol
How many moles?
M x Vsolution= mol
QUESTION
Pb(NO3)2 (aq) + NaI (aq) NaNO3(aq) + PbI 2(s)
Write a balanced Net Ionic equation for the reaction.
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What are the spectator ions in the reaction?
QUESTION
QUESTIONIf you began a reaction with the following ions in solution (all would be written with an (aq) subscript how would you represent the proper final net ionic equation? (Consult a solubility Table.)
6Na+ + 2PO43– + 3Fe2+ + 6NO3
–
A. 3Na+ + PO43– + Fe2+ + 2NO3
– No ReactionB. 6Na+ + 2PO4
3– + 3Fe2+ + 6NO3– Fe3(PO4)2 (s)+ 6NaNO3
C. 3Na+ + PO43– + Fe2+ + 2NO3
– Fe3(PO4)2 (s)+ 6 Na+ + 6 NO3–
D. 2PO43– + 3Fe2+ Fe3(PO4)2 (s)
Oxidation-Reduction
Oxidation is the loss of electrons. Reduction is the gain of electrons. The reactions occur together. One does
not occur without the other. The terms are used relative to the
change in the oxidation state or oxidation number of the reactant(s).
Aqueous Reactions:Oxidation - Reduction
In the following reaction, identify what is being oxidized and what is being reduced. What is the total number of electrons involved in the process?
Oxidation Reduction Reactions
QUESTIONIn a redox reaction, oxidation and reduction must both occur. Which statement provides an accurate premise of redox chemistry?
A.The substance that is oxidized must be the oxidizing agent.B.The substance that is oxidized must gain electrons.C.The substance that is oxidized must have a higher oxidation
number afterwards.D.The substance that is oxidized must combine with oxygen.
QUESTION
