© Copyright 1995-2007 R.J. Rusay Aqueous Reactions Dr. Ron Rusay Fall 2007

© Copyright 1995-2007 R.J. Rusay© Copyright 1995-2007 R.J. Rusay

Aqueous ReactionsAqueous Reactions

Dr. Ron RusayDr. Ron Rusay

Fall 2007Fall 2007


Aqueous ReactionsAqueous Reactions There are several general types:There are several general types:

1) 1) Precipitation: Precipitation: An insoluble salt forms An insoluble salt forms from the addition of solutions. from the addition of solutions. (Refer to Solubility Rules)(Refer to Solubility Rules)

2) 2) Acid-Base Reactions (Neutralization) Acid-Base Reactions (Neutralization) generally produces a salt plus watergenerally produces a salt plus water

3) 3) Oxidation-Reduction (Redox) Oxidation-Reduction (Redox) there is a there is a change in oxidation numbers between reactants change in oxidation numbers between reactants and productsand products

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Solution Test ApparatusSolution Test Apparatusfor Electrolytes for Electrolytes

04_43 Power Source

(a)(b)(c)+−+++−−−− −++


ConductivityConductivity

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ElectrolytesElectrolytes Aqueous solutions can be categorized into 3 Aqueous solutions can be categorized into 3

types: non-electrolytes, strong electrolytes or types: non-electrolytes, strong electrolytes or weak electrolytes based on their ability to conduct weak electrolytes based on their ability to conduct electricity.electricity.

A solution must have A solution must have ions ions to conduct.to conduct. Pure Water Pure Water does not conduct.does not conduct. Aqueous solutions can be tested for conductivity Aqueous solutions can be tested for conductivity

which will determine the degree of ionization of which will determine the degree of ionization of the solutes.the solutes.

It is possible to have full or partial ionization.It is possible to have full or partial ionization.

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ElectrolytesElectrolytes Almost all ionic compounds and a few molecular Almost all ionic compounds and a few molecular

compounds are strong electrolytes.compounds are strong electrolytes. Several molecular compounds are weak conductors, Several molecular compounds are weak conductors,

most are non-conductors.most are non-conductors. Conductivity is directly related to the amount of Conductivity is directly related to the amount of

ionization, i.e. ions in solution. Table salt, sodium ionization, i.e. ions in solution. Table salt, sodium chloride, is completely ionized: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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ElectrolytesElectrolytes

� Concentrations:Concentrations:�CaCl2 2 (s) + H2O(l) ---> CaCl2(aq) --->

0.10M Ca 2+

(aq) + 22 Cl -(aq)

0.00M 0.10M 0.20M


ElectrolytesElectrolytes Sugars like sucrose are non-ionic, molecular Sugars like sucrose are non-ionic, molecular

compounds that dissolve but produce no ions.compounds that dissolve but produce no ions.

CC1212HH2222OO11 (S)11 (S) + H + H22OO(l)(l) ----> C ----> C1212HH2222OO11 (aq)11 (aq)

Some molecular compounds like acetic acid ionize Some molecular compounds like acetic acid ionize partially (dissociate) in waterpartially (dissociate) in water

HCHC22HH33OO2 (l)2 (l) + H + H22OO(l)(l) H H33OO++(aq)(aq)+ +

0.1000M0.1000M C C22HH33OO2 2 --(aq)(aq)

0.9987M0.9987M 0.0013M0.0013M

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⇔


Aqueous AcidsAqueous Acids

� Any compound that provides a proton can be Any compound that provides a proton can be considered an acid. Strong acids are sulfuric acid, considered an acid. Strong acids are sulfuric acid, nitric acid, perchloric acid, HI, HBr and HCl.nitric acid, perchloric acid, HI, HBr and HCl.

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ElectrolytesElectrolytes

�How would the conductivity of acetic How would the conductivity of acetic acid compare to hydrochloric acid?acid compare to hydrochloric acid?

Figure 4.6 HCl Figure 4.6 HCl is Completely is Completely IonizedIonized

Figure 4.8 Figure 4.8 Acetic Acid Acetic Acid (HC(HC22HH33OO22))


Aqueous BasesAqueous Bases

Any compound that accepts a proton is a base.Any compound that accepts a proton is a base. The common bases are group IA & IIA metal The common bases are group IA & IIA metal

hydroxide compounds. They are strong bases, hydroxide compounds. They are strong bases, dissociating completely in water.dissociating completely in water.

An example of a weak base is ammonia.An example of a weak base is ammonia.

NH3 (g) + H2O(l) NH3 (aq) NH4+

(aq)+ OH-

(aq)

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⇔ ⇔

Figure 4.7 An Figure 4.7 An Aqueous Solution Aqueous Solution of Sodium of Sodium HydroxideHydroxide

Figure 4.9 The Figure 4.9 The Reaction of Reaction of NHNH33 in Water in Water

QUESTIONQUESTIONAll of the following are weak acids except: 1) HCNO. 2) HBr. 3) HF. 4) HNO2. 5) HCN.


Aqueous Reactions:Aqueous Reactions: NeutralizationNeutralization


Aqueous Reactions:Aqueous Reactions: NeutralizationNeutralization Net Ionic EquationsNet 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)


Aqueous Reactions:Aqueous Reactions: Acid-BaseAcid-Base

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QUESTIONQUESTIONIf an antacid contains Al(OH)3 it will form AlCl3 upon neutralization of stomach acid. What would be the molarity of Cl– ions in 100.0 mL of 0.010 M AlCl3?

1. 0.001 0 M2. 0.010 M3. 0.003 0 M4. 0.030 M

QUESTIONQUESTIONIn the balanced molecular equation for the neutralization of sodium hydroxide with sulfuric acid, the products are: 1) NaSO4 + H2O 2) NaSO3 + 2H2O 3) 2NaSO4 + H2O 4) Na2S + 2H2O 5) Na2SO4 + 2H2O

Pb(NO3)2 (aq) + NaI (aq)

NaNO3(aq) + PbI 2(s)

How do you know the state of the products: (s) vs. (aq)?

What type of reaction is it?Double Displacement & Precipitation

Write a balanced equation for the reaction.

2

2

QUESTIONQUESTIONGiven 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

1. 2 AlCl3 + 3 Na2CO3 also include 6 NaCl on right2. 3 Al3+ + 2 CO3

2–

3. 2 Al3+ + 3 CO32–

4. 2 Al3+ 6 Cl – + 3 CO32– + 6 Na+


Aqueous Reactions: PrecipitationAqueous Reactions: PrecipitationNet Ionic EquationsNet Ionic Equations

50mL of a 0.1M solution of sodium sulfate is 50mL of a 0.1M solution of sodium sulfate is mixed with 50mL of a 0.2M solution of silver mixed with 50mL of a 0.2M solution of silver nitrate. What is the result?nitrate. What is the result?

Molecular Equation:Molecular Equation:

?Na?Na22SOSO4(aq)4(aq)+ ?AgNO+ ?AgNO3(aq)3(aq) ---> --->

?Ag?Ag22SOSO4(s) 4(s) + ?NaNO+ ?NaNO3(aq)3(aq)

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1 2

1 2


Aqueous Reactions: PrecipitationAqueous Reactions: PrecipitationNet Ionic Equations

NaNa22SOSO4(aq)4(aq)+ 2 AgNO+ 2 AgNO3(aq)3(aq)-->Ag-->Ag22SOSO4(s)4(s)+ + 0.1M0.1M 0.2M0.2M 2 NaNO 2 NaNO3(aq)3(aq)

Ionic Reaction (Reactants):Ionic Reaction (Reactants):

NaNa22SOSO4(aq) 4(aq) 22 Na Na++(aq)(aq) + SO + SO44

2-2-(aq)(aq)

22 AgNO AgNO3(aq) 3(aq) 22 Ag Ag++(aq)(aq) + + 2 2 NONO33

1-1-(aq)(aq)

2 Na2 Na++(aq)(aq)+ SO+ SO44

2-2-(aq)(aq)+ 2 Ag+ 2 Ag++

(aq)(aq)+ 2 NO+ 2 NO331-1-

(aq)(aq)

0.2M0.2M 0.1M0.1M 0.2M0.2M 0.2M 0.2M

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NaNa22SOSO4(aq)4(aq)+ 2 AgNO+ 2 AgNO3(aq)3(aq)-->Ag-->Ag22SOSO4(s)4(s)+ + 0.1M0.1M 0.2M0.2M 2 NaNO 2 NaNO3(aq)3(aq)

Ionic Reaction (Products):Ionic Reaction (Products):

2 NaNO2 NaNO3(aq) 3(aq) 22 Na Na++(aq)(aq) + 2 NO + 2 NO33

1-1-(aq)(aq)

AgAg22SOSO4(s) 4(s) Does not dissolve (ionize)Does not dissolve (ionize)

2Na2Na++(aq)(aq)+ 2NO+ 2NO33

1-1-(aq) (aq) + Ag+ Ag22SOSO4(s)4(s)

0.2M0.2M 0.2M 0.2M solid solid

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NaNa22SOSO4(aq)4(aq)+ 2 AgNO+ 2 AgNO3(aq)3(aq)-->Ag-->Ag22SOSO4(s)4(s)+ +

2 NaNO2 NaNO3(aq)3(aq)

Overall Ionic Reaction:Overall Ionic Reaction:

2Na2Na++(aq)(aq)+ SO+ SO44

2-2-(aq) (aq) +2Ag+2Ag++

(aq)(aq)+ 2NO+ 2NO331-1-

(aq) (aq)

2Na2Na++(aq)(aq) + Ag + Ag22SOSO4(s) 4(s) + 2NO+ 2NO33

1-1-(aq) (aq)

Net Ionic Equation: (Subtract Spectator Ions)Net Ionic Equation: (Subtract Spectator Ions)

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2Ag2Ag++(aq)(aq)+ SO+ SO44

2-2-(aq) (aq) AgAg22SOSO4(s) 4(s)

= MNa2SO4 xVNa2SO4 / 1:1stoichiometry

= 0.10M x 0.050 L/ 1= 0.0050 mol

How many moles?How many moles?

QUESTIONQUESTIONThe net ionic equation for the reaction of aluminum sulfate and sodium hydroxide contains which of the following species? 1) 3Al

3+(aq)

2) OH–(aq)

3) 3OH–(aq)

4) 2Al3+

(aq) 5) 2Al(OH)3(s)

Pb(NO3)2 (aq) + NaI (aq)

NaNO3(aq) + PbI 2(s)

Write a balanced Net Ionic equation for the reaction.

2

2

Pb 2+ (aq) + 2 I 1- (aq) PbI 2(s)

What are the spectator ions in the reaction?

2 Na 1+ (aq); 2 NO31- (aq)

QUESTIONQUESTIONWhich of the following salts is insoluble in water? 1) Na2S 2) K3PO4 3) Pb(NO3)2 4) CaCl2 5) All of these are soluble in water.

QUESTIONQUESTIONIf 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

–

1. 3Na+ + PO43– + Fe2+ + 2NO3

– No Reaction2. 6Na+ + 2PO4

3– + 3Fe2+ + 6NO3– Fe3(PO4)2 (s)+ 6NaNO3

3. 3Na+ + PO43– + Fe2+ + 2NO3

– Fe3(PO4)2 (s)+ 6 Na+ + 6 NO3–

4. 2PO43– + 3Fe2+ Fe3(PO4)2 (s)


Aqueous Reactions:Aqueous Reactions:Oxidation - Reduction Oxidation - Reduction

� In the following reaction, identify what is being In the following reaction, identify what is being oxidized and what is being reduced. What is oxidized and what is being reduced. What is the total number of electrons involved in the the total number of electrons involved in the process?process?

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QUESTIONQUESTIONIn a redox reaction, oxidation and reduction must both occur. Which statement provides an accurate premise of redox chemistry?

1. The substance that is oxidized must be the oxidizing agent.2. The substance that is oxidized must gain electrons.3. The substance that is oxidized must have a higher oxidation

number afterwards.4. The substance that is oxidized must combine with oxygen.


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© Copyright 1995-2007 R.J. Rusay Aqueous Reactions Dr. Ron Rusay Fall 2007