1 types of chemical reactions and solution stoichiometry chapter 4

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Types of Chemical Reactions Types of Chemical Reactions and Solution Stoichiometryand Solution StoichiometryChapter 4Chapter 4

2

Water, the Common Water, the Common SolventSolvent

Section 4.1Section 4.1

3

• Type of bond?

• Shape?

• Polarity?

Nature of WaterNature of Water

Covalent

Polar

Bent/Angular

4

• Ionic solids that dissolve are soluble.• Ionic solids will dissolve in polar solvents

but not nonpolar solvents• Water molecules break the crystal lattice

into separate ions. This is dissociation.• Then the water molecules surround the

ions. This is hydration. • Ionic solids that do not dissolve are

insoluble.

Ionic Solute-Solvent Ionic Solute-Solvent InteractionInteraction

5p. 411

Ion

ic S

olu

te-S

olv

en

t In

tera

cti

on

Ion

ic S

olu

te-S

olv

en

t In

tera

cti

on

6Solu

bilit

y o

f C

om

pou

nd

sS

olu

bilit

y o

f C

om

pou

nd

s

notes

7Solu

bilit

y o

f C

om

pou

nd

sS

olu

bilit

y o

f C

om

pou

nd

s

notes

8

• Miscible – Liquids that dissolve freely in one another in any proportion.

• Immiscible – Liquids that are not soluble in each other.

• “Likes dissolve likes”Polar solutes dissolve in polar

solvents.Nonpolar solutes dissolve in

nonpolar solvents.• Alcohols are slightly polar.

Liquid Solute-Solvent Liquid Solute-Solvent InteractionInteraction

9Mis

cib

le a

nd

Im

mis

cib

leM

iscib

le a

nd

Im

mis

cib

le

10p. 412

Immiscible & MiscibleImmiscible & Miscible

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The Nature of Aqueous The Nature of Aqueous SolutionsSolutions

Section 4.2Section 4.2

12

• A homogeneous mixture of two or more substances in a single phase

• Particles are thoroughly mixed and remains mixed indefinitely

• Components of a solution– Solvent: does the dissolving; the larger

amount– Solute: is being dissolved; the smaller

amount

SolutionSolution

13p. 406

Electric Conductivity in Electric Conductivity in SolutionsSolutions

14

• Electrolyte – a substance that dissolves in water to give a solution that conducts electric current

• Nonelectrolytes – a substance that dissolves in water to give a

solution that does not conduct electricity– Does not produce ions– Example: sugar and ethanol

Electrolytes & Electrolytes & NonelectrolytesNonelectrolytes

15

• Completely ionized when they are dissolved in water

• Three classes– Soluble Salts

– Strong Acids: produce H+ ions when dissolved in water•HCl (g) + H2O (l) H3O+ (aq) + Cl- (aq)

– Strong Bases: produce OH- ions when dissolved in water•NaOH (s) Na+ (aq) + OH- (aq)

Strong ElectrolytesStrong Electrolytes

NaCl (s) Na1+(aq)

+ Cl1-(aq)

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An acid that ionizes completely in aqueous solution.

STRONG ACID LISTHCl hydrochloric acidHI hydroiodic acidHBr hydrobromic acidH2SO4 sulfuric acidHNO3 nitric acidHClO3 chloric acidHClO4 perchloric acid

Strong AcidsStrong Acids

MEMORIZE!

MEMORIZE!

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Strong Bases – bases that dissociate completely – strong electrolytes

Formed from Group I & II metalscombined with hydroxide

Strong BasesStrong Bases

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• Substances that exhibit a small degree of ionization in water

• Two classes– Weak Acids: produce few H+ ions when

dissolved in water

CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+

(aq)

– Weak Bases: produce few OH- ions when dissolved in waterNH3 (aq) + H2O (l) NH4

+ (aq) + OH-(aq)

Weak ElectrolytesWeak Electrolytes

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The Composition of The Composition of SolutionsSolutions

Section 4.3Section 4.3

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The number of moles of solute in one liter of solution.

MolarityMolarity

MM = =moles of solutemoles of solute

liters of solutionliters of solution

MM = =molmol

LL

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1. Calculate the molarity of a solution prepared by dissolving 11.5 g of solid NaOH in enough water to make 1.50 L of solution.

2. Give the concentrations of each type of ion in the following solutions:a. 0.50 M Co(NO3)2

b. 1 M Fe(ClO4)3

3. Calculate the number of moles of chloride ions in 1.75 L of 1.0 x 10-3 M ZnCl2.

4. Typical blood serum is about 0.14 M NaCl. What volume of blood contains 1.0 mg NaCl?

Molarity Practice ProblemsMolarity Practice Problems

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• A solution whose concentration is accurately known.– To analyze the alcohol content of a certain

wine, a chemist needs 1.00 L of an aqueous 0.200 M K2Cr2O7 solution. How much solid potassium dichromate must be weighed out to make this solution?

Standard SolutionStandard Solution

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• A solution in concentrated form.• Dilution: process where water is added

to achieve the molarity desired for a particular solution.

• If the mole ratio is 1:1, then M1V1=M2V2 can be used– What volume of 16 M sulfuric acid must be

used to prepare 1.5 L of a 0.10 M sulfuric acid solution?

DilutionDilution

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Precipitation ReactionsPrecipitation Reactions

Section 4.5Section 4.5

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• Two solutions mix and an insoluble solid forms

• The solid that forms is called a precipitate.

• Predicting Reaction Products:– Using the solubility rules, predict what will

happen when the following pairs of solutions are mixed.• Potassium nitrate and barium chloride• Sodium sulfate and lead (II) nitrate• Potassium hydroxide and iron (III) nitrate

Precipitation ReactionsPrecipitation Reactions

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Describing Reactions in Describing Reactions in SolutionSolution

Section 4.6Section 4.6

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NET IONIC EQUATION• Write the balanced equation for the

reaction between ammonium sulfide and cadmium II nitrate. Be sure to include states of matter

• What type of reaction is it? What are the products?(NH4)2S (aq) + Cd(NO3)2 (aq)

2 NH4NO3 (aq) + CdS

(s)

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NET IONIC EQUATION

Each (aq) is dissociated. The (s) is not dissociated; it is the precipitate.

(NH4)2S (aq) + Cd(NO3)2 (aq) 2 NH4NO3 (aq) + CdS

(s)

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NET IONIC EQUATION(NH4)2S (aq) + Cd(NO3)2 (aq) 2 NH4NO3 (aq) + CdS

(s)

(NH4

)S

+ +

Cd

1+ 2-

(aq) (aq)

(NO3

)

2+ 1-

(aq) (aq)

NH4NO3

+ +1+ 1-

(aq) (aq)

2 2 2 2

CdS

+(s)

Break all (aq) into ions; not the (s)

Balance and add states

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NET IONIC EQUATION(NH4)2S (aq) + Cd(NO3)2 (aq) 2 NH4NO3 (aq) + CdS

(s)

(NH4

)S+ + Cd

1+ 2-

(aq) (aq)

(NO3

)

2+ 1-

(aq) (aq)

NH4NO3+ +

1+ 1-

(aq) (aq)

2 2 2 2 CdS+(s)

Identify spectator ions and remove

Write what’s left.

+

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2-

NET IONIC EQUATION(NH4)2S (aq) + Cd(NO3)2 (aq) 2 NH4NO3 (aq) + CdS

(s)

(NH4

)

S

+ +

Cd

1+

(aq)

(aq)

(NO3

)

2+

1-

(aq)

(aq)

NH4NO3+ +

1+ 1-

(aq) (aq)

2 2 2 2

CdS

+

(s)

This is the net ionic equation.

+

32

Ag(NO3) + NaCl

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NET IONIC EQUATION• Write the balanced equation for the

reaction between sodium chloride and silver nitrate. Be sure to include states of matter

• What type of reaction is it? What are the products?NaCl (aq)+ Ag(NO3) (aq) NaNO3 (aq)+ AgCl (s)

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NaCl (aq) + AgNO3 (aq) NaNO3 (aq) + AgCl (s)

NET IONIC EQUATIONN

aCl

+ +

Ag

1+ 1-

(aq) (aq)

NO3

1+ 1-

(aq) (aq)

NaNO3

+ +1+ 1-

(aq) (aq)

AgCl

+(s)

Break all (aq) into ions; not the (s)

Balance and add states

35

+

NaCl (aq) + AgNO3 (aq) NaNO3 (aq) + AgCl (s)

NET IONIC EQUATION

Na

Cl+ + Ag1+ 1-

(aq) (aq)

NO31+ 1-

(aq) (aq)

Na

NO3+1+ 1-

(aq) (aq)

AgCl+(s)

Identify spectator ions and remove

Write what’s left.

+

36

This is the net ionic equation.

+

NaCl (aq) + AgNO3 (aq) NaNO3 (aq) + AgCl (s)

NET IONIC EQUATION

Na

Cl

+ +

Ag

1+

1-

(aq)

(aq)

NO3

1+

1-

(aq)

(aq)

Na

NO3+1+ 1-

(aq) (aq)

AgCl

+

(s)

+

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Stoichiometry of Stoichiometry of Precipitation ReactionsPrecipitation Reactions

Section 4.7Section 4.7

38

1. When aqueous solutions of sodium sulfate and lead (II) nitrate are mixed, lead (II) sulfate precipitates. Calculate the mass of lead (II) sulfate formed when 1.25 L of 0.0500 M lead (II) nitrate and 2.00 L of 0.0250 M sodium sulfate are mixed.

Determining the mass of Determining the mass of product formedproduct formed

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Acid-Base ReactionsAcid-Base Reactions

Section 4.8Section 4.8

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Brønsted-Lowry Acid & BaseBrønsted-Lowry Acid & Base

H

NH3(aq) + H2O(l) NH4+

(aq) + OH-

(aq)N

H

O

HH N HH

H +

OH-

HH

A molecule

or ion that is a proton

donorACID

A molecule or ion that is a proton acceptor

BASE

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The reaction of hydronium ions and hydroxide ions to form water molecules.

Neutralization ReactionsNeutralization Reactions

HCl(aq) + NaOH(aq) NaCl(aq) + HOH(l)

ACID + BASE SALT + WATER

H++Cl- + Na++OH- Na++Cl- + HOH

H+ (aq)

+ OH- (aq) HOH (l)

42

The reaction of hydronium ions and hydroxide ions to form water molecules.

Neutralization ReactionsNeutralization Reactions

HC2H3O2 (aq) + KOH(aq) KC2H3O2(aq) + HOH(l)

ACID + BASE SALT + WATER

HC2H3O2 + K++OH- K++C2H3O2-1+ HOH

HC2H3O2(aq) + OH-

(aq) HOH (l) + C2H3O2

-1(aq)

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1. What volume of a 0.100 M HCl solution is needed to neutralize 25.0 mL of 0.350 M NaOH?

2. In a certain experiment, 28.0 mL of 0.250 M HNO3 and 53.0 mL of 0.320 M KOH are mixed. Calculate the amount of water formed in the resulting reaction. What is the concentration of H+ and OH- ions in excess after the reaction goes to completion.

Neutralization ReactionsNeutralization Reactions

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• Delivery from a buret of a measured volume of a solution of known concentration (the titrant) into a solution containing the substance to be analyzed (the analyte)

• Equivalence point: the point in a titration where enough titrant has been added to react exactly with the analyte

• Endpoint: The point where the indicator actually changes color

Acid-Base TitrationAcid-Base Titration

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1. A student weighs out a 1.3009 g sample of KHC8H4O4 . KHP has one acidic hydrogen. The student dissolves the KHP in distilled water, adds phenolpthalein and titrates the solution with sodium hydroxide to the endpoint. The difference between the final and initial buret readings indicates that 41.20 ML of the sodium hydroxide is required to react exactly with the KHP. Calculate the concentration of sodium hydroxide.

Neutralization Neutralization Titration/AnalysisTitration/Analysis

46

2. An environmental chemist analyzed the effluent from an industrial process known to produce the compounds CCl4 and HC7H5O2, a weak acid with one acidic hydrogen. A sample of the effluent weighing 0.3518 g was shaken with water and the resulting aqueous solution required 10.59 mL of 0.1546 M NaOH for neutralization. Calculate the mass percent of HC7H5O2 in the original sample.

Neutralization Neutralization Titration/AnalysisTitration/Analysis