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CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
CONCEPT: MOLARITY
Molarity (M) can serve as the connection between the interconversion of ____________ to ____________ and vice versa.
For example, a 5.8 M NaCl solution really means __________________________ per __________________________.
Molarity =MolesSolute)(LitersSolution)(
A typical mixture consists of a smaller amount of one substance, the ________________, dissolved in a larger amount of
another substance, the __________________. Together they form a __________________.
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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PRACTICE: MOLARITY
EXAMPLE 1: 2.64 grams of an unknown compound was dissolved in water to yield
150 mL of solution. The concentration of the solution was 0.075 M. What was the
molecular weight of the substance?
EXAMPLE 2: A solution is prepared by dissolving 0.1408 mol calcium nitrate, Ca(NO3)2, in enough water to make 100.0 mL
of stock solution. If 20.0 mL of this solution is then mix with an additional 90 mL of deionized water, calculate the
concentration of the calcium nitrate solution.
PRACTICE 1: What is the molarity of calcium ions of a 650 mL solution containing 42.7 g of calcium phosphate?
PRACTICE 2: A solution with a final volume of 750.0 mL was prepared by dissolving 30.00 mL of benzene (C6H6, density =
0.8787 gmL
) in dichloromethane. Calculate the molarity of benzene in the solution.
M =MolesSolute)(LitersSolution)(
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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CONCEPT: MOLARITY & CHEMICAL REACTIONS
Whenever we are provided given information in a reaction we use ___________________ to find any unknown information.
• In aqueous reactions, this given information is typically in units of __________________ or __________________ .
Entities means ______________________ , ______________________ or ______________________.
Volume of Given Moles of Given Moles of Unknown Volume of Unknown
Entities of Unknown
Grams of Unknown
Use this chart when given a chemical equation with the known quantity in either ________ or ________ of a compound or
element and asked to find the unknown quantity of another compound or element.
EXAMPLE: How many grams of sodium metal are needed to react with 38.74 mL of 0.275 M NaOH?
2 Na (s) + 2 H2O (l) H2 (g) + 2 NaOH (aq)
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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PRACTICE: MOLARITY & CHEMICAL REACTIONS
PRACTICE 1: How many milliliters of 0.325 M HCl are needed to react with 16.2 g
of magnesium metal?
2 HCl (aq) + Mg (s) MgCl2 + H2 (g)
PRACTICE 2: What is the molarity of a hydrobromic acid solution if it takes 34.12 mL of HBr to completely neutralize 82.56
mL of 0.156 M Ca(OH)2?
2 HBr (aq) + Ca(OH)2 (aq) CaBr2 (aq) + 2 H2O (l)
PRACTICE 3 (CHALLENGE): Iron (III) can be oxidized by an acidic K2Cr2O7 solution according to the net ionic equation:
Cr2O72- + 6 Fe2+ + 14 H+ 2 Cr3+ + 6 Fe3+ + 7 H2O
If it takes 30.0 mL of 0.100 M K2Cr2O7 to titrate a 25 mL Fe2+ solution, what is the molar concentration of Fe2+?
M =MolesSolute)(LitersSolution)(
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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CONCEPT: AQUEOUS SOLUTIONS
The ___________________________ of a compound represents the maximum amount of solute that dissolves in a solvent.
SOLUBILITY RULES
SOLUBLE IONIC COMPOUNDS
INSOLUBLE IONIC COMPOUNDS
1. Group 1A ions (Li+, Na+, K+, etc.) and ammonium ion (NH4+) are soluble.
1. (Hydroxides) OH- and (Sulfides) S2-, are insoluble
except when with Group 1A ions (Li+, Na+, K+, etc.),
ammonium ion (NH4+) and Ca2+, Sr2+, Ba2+.
2. (Nitrates) NO3- , (acetates) CH3COO- or C2H3O2-,
and most perchlorates (ClO4-) are soluble.
2. (Carbonates) CO32- and (Phosphates) PO43- are
insoluble except when with Group 1A ions
(Li+, Na+, K+, etc.), ammonium ion (NH4+).
3. Cl- , Br- , and I- are soluble, except when paired
with Ag+ , Pb2+ , Cu+ and Hg22+.
4. (Sulfates) SO42- are soluble, except those of Ca2+ ,
Sr2+ , Ba2+ , Ag+ , and Pb2+ .
When we classify a compound as soluble it means that the compound is _______________________, it is also known as
a(n) _______________________ because it conducts electricity.
NaNO3 (s) H2O
Na+ (aq) + NO3– (aq)
When we classify a compound as insoluble it means that the compound is a _______________________, it is also known
as a(n) _______________________ because it doesn’t conduct electricity.
CH3OH (l) H2O
CH3OH (aq)
BaSO4 (s) H2O
BaSO4 (aq)
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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CONCEPT: WRITING CHEMICAL REACTIONS
EXAMPLE: Predict whether a reaction occurs, and write the balanced molecular equation.
a. LiOH (aq) + MgSO4 (aq)
EXAMPLE: Predict whether a reaction occurs, and write the balanced molecular equation, the total and net ionic equations.
Molecular: Na2CO3 (aq) + HBr (aq)
Total Ionic:
Net Ionic:
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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PRACTICE: Predict whether a reaction occurs, and write the balanced total and net ionic equations.
Total Ionic:
Net Ionic:
Molecular: Ag2SO4 (aq) + KCl (aq)
PRACTICE: Predict whether a reaction occurs, and write the balanced total and net ionic equations.
Total Ionic:
Net Ionic:
Molecular: MgBr2 (aq) + NaC2H3O2 (aq)
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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CONCEPT: ELECTROLYTES
Whenever we add a solute into a solvent three outcomes are possible:
• the solute will _________________ dissolve ( STRONG electrolytes).
• the solute will _________________ dissolve ( WEAK electrolytes).
• the solute will _________________ dissolve ( NON electrolytes).
Classification of Solutes in Aqueous Solution
STRONG ELECTROLYTES
WEAK ELECTROLYTES
NONELECTROLYTES
1. STRONG ACIDS: HCl, ______ , HI ,
HNO3 , _______ , _______ , _______ .
2. STRONG BASES:
Group 1A Metal with OH-, H-, O2- or
NH2-
Groups 2A Metal, Calcium or Lower, with
OH-, H-, O2- or NH2-
3) SOLUBLE IONIC COMPOUNDS:
1. WEAK ACIDS: HF, ____________ ,
________ , ________ , ________ .
2. WEAK BASES: Be(OH)2 , Mg(OH)2 ,
_________ , _________ .
1. MOLECULAR
COMPOUNDS:
______________
C6H12O6 (glucose)
C12H22O11 (sucrose)
______________
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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PRACTICE: ELECTROLYTES
EXAMPLE: Each of the following reactions depicts a solute dissolving in water. Classify each solute as a strong electrolyte,
a weak electrolyte or a non-electrolyte.
a. PbSO4 (s) PbSO4 (aq)
b. HC2H3O2 (aq) H+ (aq) + C2H3O2– (aq)
c. CaS (s) Ca2+ (aq) + S2- (aq)
d. Hg (l) Hg (aq)
PRACTICE: Classify each of the following solutes as either a strong electrolyte, a weak electrolyte or a non-electrolyte.
a. Perbromic acid, HBrO4
b. Lithium chloride, LiCl
c. Formic Acid, HCO2H
d. Methylamine, CH3NH2
e. Zinc bromide, ZnBr2
f. Propanol, C3H8OH
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
CH. 8 - INTRODUCTION TO SOLUTIONS AND AQUEOUS REACTIONS
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CONCEPT: BALANCING REDUCTION-OXIDATION REACTIONS
When balancing a redox reaction we balance them in terms of the number of electrons transferred between reactants. Balancing A Redox Reaction in Acidic Reactions: STEP 1: Write the equation into 2 half-reactions.
STEP 2: Balance elements that are not oxygen or hydrogen.
STEP 3: Balance Oxygens by adding _______.
STEP 4: Balance Hydrogens by adding _______.
STEP 5: Balance overall charge by adding e– to the more _______ side. Both reactions must have an equal number of e –.
STEP 6: Combine the half-reactions and cross out reaction intermediates.
Balancing A Redox Reaction in Basic Reactions: Follow Steps 1-6 from above.
STEP 7: Balance remaining H+ by adding an equal amount _______ ions to both sides of the chemical reaction.
EXAMPLE: Balance the following reaction in an acidic solution.
O2– + F2 O2 + F–
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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PRACTICE: BALANCING REDUCTION-OXIDATION REACTIONS
EXAMPLE 1: Balance the following reaction in an acidic solution. NO2– NO3– + NO
EXAMPLE 2: Balance the following reaction in a basic solution.
Cr2O72– + Hg Hg2+ + Cr3+
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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CONCEPT: SINGLE REPLACEMENT REACTIONS In a single replacement or displacement reaction one element displaces another element from a compound. More reactive or active metals displace less reactive metals or hydrogen from compounds.
Act
ivit
y In
crea
ses
Metals
Lithium (Li) > Potassium (K) > Barium (Ba) > Strontium (Sr) > Calcium (Ca) > Sodium (Na)
Activity
Metals in this category can displace hydrogen from liquid water, steam and acids:
Metals
Magnesium (Mg) > Aluminum (Al) > Zinc (Zn2+) > Chromium (Cr2+, Cr3+) > Iron (Fe2+, Fe3+)
Activity
Metals in this category can displace hydrogen from steam and acids:
Metals
Cadmium (Cd2+) > Cobalt (Co2+, Co3+) > Nickel (Ni2+) > Tin (Sn2+, Sn4+) > Lead (Pb2+, Pb4+)
Activity
Metals in this category can displace hydrogen from acids:
Hydrogen and Metals
Hydrogen (H) > Antimony (Sb3+) > Arsenic (As3+, As5+) > Bismuth (Bi3+) > Copper (Cu+, Cu2+) > Mercury (Hg22+, Hg2+) > Silver (Ag+) > Palladium (Pd3+) > Platinum (Pt2+, Pt3+) > Gold (Au+, Au3+)
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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PRACTICE: SINGLE REPLACEMENT REACTIONS EXAMPLE 1: Based on your understanding of activities determine if a reaction occurs and if so provide the products formed.
Ba (s) + H2O (g)
EXAMPLE 2: Based on your understanding of activities determine if a reaction occurs and if so provide the products formed.
Zn (s) + NiCl2 (aq)
EXAMPLE 3: If the activity of halogens is stated as: Fluorine > Chlorine > Bromine > Iodine, determine if a reaction occurs and if so provide the products formed.
Cl2 (g) + AlBr3 (aq)
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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CONCEPT: NORMALITY
Another measurement for concentration usually encountered is normality (N), which represents the number of equivalents per liter of solution.
N =equivalents of soluteLiters of solution
equivalent (eq) = n ×moles
• An equivalent is the mass of a compound that can either donate or accept an __________ or __________.
An equivalent (eq) and n are both determined by the compound being used (acid or base) and if the compound is undergoing a redox reaction.
Acids
For an acid the number for n is based on the number of _________________________ present.
EXAMPLE 1: Determine the number of equivalents for each of the acids given.
a) 2.5 moles CH3COOH b) 133.4 g H3PO4
Bases
For a base the number for n is based on the number of _________________________ present.
EXAMPLE 2: Determine the number of equivalents for the following base.
a) 50.0 mL of 0.165 M Ca(OH)2
Redox Reactions
For a redox reaction the number for n is based on the number of ________________________ transferred.
EXAMPLE 3: Based on the given redox reaction determine the value for n.
MnO4– (aq) + H+ (aq) Mn2+ (aq) + H2O (l)
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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PRACTICE: NORMALITY EXAMPLE 1: What is the normality of a solution made by dissolving 325.1 g HNO3 in enough water to create a 750.0 mL solution?
EXAMPLE 2: Determine the equivalent weight of the following compounds.
a) Al(OH)3 b) H2CO3
EXAMPLE 3: What volume, in mL, of 50.0 g H2SO4 is needed to create a 0.300 N H2SO4 solution?
EXAMPLE 4: If a concentrated 3.25 M H3PO4 solution possesses a density of 1.350 g/mL, what is its normality?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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16. How many milligrams of NaCN are required to prepare 712 mL of 0.250 M NaCN?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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17. What volume (in µL) of 0.100 M HBr contains 0.170 moles of HBr?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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18. How many moles of Ca2+ ions are in 0.100 L of a 0.450 M solution of Ca3(PO4)2?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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19. How many chloride ions are present in 65.5 mL of 0.210 M AlCl3 solution? a) 4.02 × 1023 chloride ions
b) 5.79 × 1024 chloride ions
c) 2.48 × 1022 chloride ions
d) 8.28 × 1021 chloride ions
e) 1.21 × 1022 chloride ions
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22. To what final volume would 100 mL of 5.0 M KCl have to be diluted in order to make a solution that is 0.54 M KCl?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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23. If 880 mL of water is added to 125.0 mL of a 0.770 M HBrO4 solution what is the resulting molarity?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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26. Consider the following balanced redox equation:
H2O + 2 MnO4 – + 3 SO32- 2 MnO2 + 3 SO42- + 2 OH – How many grams of MnO2 (MW: 86.94 g/mol) are produced when 32.0 mL of 0.615 M MnO4- (MW: 118.90 g/mol) reacts with excess water and sulfite?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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27. Iron (III) can be oxidized by an acidic K2Cr2O7 solution according to the net ionic equation:
Cr2O72- + 6 Fe2+ + 14 H+ 2 Cr3+ + 6 Fe3+ + 7 H2O
If it takes 35.0 mL of 0.250 M FeCl2 to titrate 50 mL of a solution containing Cr2O72-, what
is the molar concentration of Cr2O72-?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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28. Vinegar is a solution of acetic acid, CH3COOH, dissolved in water. A 5.54 g sample of
vinegar was neutralized by 30.10 mL of 0.100 M NaOH. What is the percent by weight of
acetic acid in the vinegar?
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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29. What is the molar mass of a 0.350 g sample of a monoprotic acid if it requires 50.0 mL of 0.440 M Ca(OH)2 to completely neutralize it?
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30. Give the complete ionic equation for the reaction (if any) that occurs when aqueous solutions of sodium sulfide and copper (II) nitrate are mixed. a) Na+ (aq) + SO42-(aq) + Cu+(aq) + NO3-(aq) CuS(s) + Na+(aq) + NO3-(aq)
b) Na+ (aq) + S-(aq) + Cu+(aq) + NO3-(aq) CuS(s) + NaNO3(aq)
c) 2 Na+(aq) + S2-(aq) + Cu2+(aq) + 2 NO3-(aq) Cu2+(aq) + S2-(aq) + 2 NaNO3(s)
d) 2 Na+(aq) + S2-(aq) + Cu2+(aq) + 2 NO3-(aq) CuS(s) + 2 Na+(aq) + 2 NO3-(aq)
e) No reaction occurs.
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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31. Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of H2SO4 and KOH are mixed. a) H+(aq) + OH-(aq) H2O(l)
b) 2 K+(aq) + SO42-(aq) K2SO4(s)
c) H+(aq) + OH-(aq) + 2 K+(aq) + SO42-(aq) H2O(l) + K2SO4(s)
d) H22+(aq) + OH-(aq) H2(OH)2(l)
e) No reaction occurs.
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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32. Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of Na2CO3 and HCl are mixed. a) 2 H+(aq) + CO32-(aq) H2CO3(s)
b) 2 Na+(aq) + CO32-(aq) + 2 H+(aq) + 2 Cl-(aq) H2CO3(s) + 2 NaCl(aq)
c) 2 H+(aq) + CO32-(aq) H2O(l) + CO2(g)
d) 2 Na+(aq) + CO32-(aq) + 2 H+(aq) + 2 Cl-(aq) H2CO3(s) + 2 Na+(aq) + 2 Cl-(aq)
e) No reaction occurs.
CHEMISTRY - TRO-STRUCTURE & PROPERTIES 2E
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