Download Oxidation-reduction reactions and electrochemistry

School of Biomedical Biomolecular and Chemical Sciences
Unit Outline
Inorganic and Physical Chemistry
CHEM1101
Semester: 1
Campus: Crawley
Unit Coordinator: Assoc. Prof. Bob Bucat
This outline is the currently available version for this unit. Detailed Information on unit
content and assessment may undergo modification before the time of delivery of the
unit. For the most up to date information students must consult material supplied to
enrolled students by the unit co-ordinator.
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Copying of this material by students, except for fair dealing purposes under the Copyright Act, is prohibited. For the
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© The University of Western Australia 2001
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Introduction
This unit is primarily for science students who intend to major in Chemistry or proceed with
Level 2 chemistry major units. During the semester the integrated laboratory/lecture
programme is concerned with physical and inorganic chemistry. Content includes categories
of chemical reaction in aqueous solution, and participation of water molecules in reactions;
solubility, acid-base and complexation equilibria in aqueous solution; periodic trends of
properties of the elements, and models of atomic structure to account for these; simple
models of bonding; overview of chemistry of main block and first row transition elements;
oxidation-reduction reactions and electrochemistry; thermodynamics of reactions, and the
concept of stability; phase equilibria and phase changes in one- and two-component systems;
properties of solutions.
Advisable Prior Study
Although some revision will be presented, a reasonable knowledge of the Year 11/12 school
Chemistry syllabus will be assumed.
Technical Requirements
Laboratory Notebook
Detailed records of plans, observations, measurements, thought processes, inferences
conclusions, and answers to questions must be kept during laboratory classes in a dedicated
notebook. The notebook should have a hard cover, with ruled pages that are properly bound.
Graph paper pages are not necessary
Calculator
You should have a scientific calculator to use in the laboratory.
Lab Coat
Every student must wear a lab coat in the laboratory classes.
Footwear
You will not be allowed into the lab classes in bare feet, thongs, sandals or other open shoes.
Software Requirements
Students are required to arrange their own access to word processing and spreadsheet and
graphing software. Microsoft Word and Excel are recommended and instructions and
templates contained in course materials will assume that this is the software employed.
Contact Details
Unit web site (may include Web CT URL): http://Webct.uwa.edu.au/
Name of Unit coordinator: Associate Professor Bob Bucat
e-mail: [email protected]
Phone: 6488 3158
Fax: 6488 1005
Consultation hours: By appointment
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Unit Structure Summary
Lectures
Three 1-hour lectures per week – Tuesday, Wednesday and Friday in the Tattersall Lecture
Theatre.
Practical and/or Laboratory Sessions
Nine laboratory sessions, each of three hours duration, in weeks that suit integration with the
lecture content. Provisionally, these will be held in weeks 3-7 and 9-13 of semester.
Attendance is compulsory at either of the alternative sessions on Monday 10 am – 1 pm and
Monday 2 pm – 5 pm. Severe discounts to the mark awarded for practical work are applied for
non-attendances.
Tutorials
Three timeslots will be made available for discussion/clarification of the presented course
content. The basis of discussion will usually be a weekly worksheet, but it is expected that
tutors will mainly respond to student queries. Attendance is optional.
Course Content
References are to Chemistry: The Molecular Nature of Matter and Change by M. Silberberg
(3rd Edition). References in square brackets - eg, [pp.767-8] - are to Silberberg, 2nd edition
Behaviour of Water pp.132-8, 420-3, 442-5
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[134-41, 421-5, 444-7]
Remarkable physical properties, rationalisation in terms of hydrogen bonds.
Role as a solvent and reaction medium. Solubility/insolubility in terms of cation-anion vs.
ion-water forces of attraction.
Effective independence of ions in dilute solutions. Difference between what is put into
solution and what is in solution. Chemistry of solutions as sum of individual chemistries of
cation and anion.
Reactions of water: formation (by neutralisation, combustion), decomposition (both
oxidation and reduction by electrolysis), reduction by reducing agents, oxidation by
oxidising agents.
Temperature dependence of Kw, change of neutral pH with temperature.
Indefinability of what meant by H+(aq), transient nature of various H+(aq) species.
Basic notions of stability - a concept that has meaning only in a relative sense, related to
direction of reaction that takes system closer to equilibrium. Distinction between
thermodynamic stability (A reaction mixture at equilibrium) and kinetic stability
(Apparently at equilibrium because of negligible rate of reaction). Nil reference in text.
Types of “Inorganic” Reaction in Aqueous Solution
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Oxidation-reduction, precipitation, formation of weak electrolytes (especially water), Ch. 4
[Ch.4] seen as competition processes (little attention given to this notion in textbook).
Qualitative notion of “driving forces” of competing reactions - eg, in the case of pHdependent solubilities of salts of weak acids, insolubility of salt (eg, CaCO 3) vs. strength
of weak acid (HCO3- and H2CO3) pp. 829-30 [829-30]
Aquation of metal ions seen as complex ion formation - eg Al(H2O)63+ pp. 786 [785-6]
Complexation as a competition process. Concentration-dependent speciation - eg,
changes of relative amounts of species due to successive substitution of H 2O ligands by
OH- ligands as pH increases, amphoterism. Substitution of H2O by other ligands such as
NH3, Cl- etc. Qualitative aspects of #19.4 [19.4]
Notion of “stabilisation” by complexation.
Overlap of complexation and Lewis acid-base concepts pp. 786, 791-5 [785-6, 791-4]
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Course Content continued
Chemical Equilibrium, General Principles - Ch. 17 [Ch. 17]
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Prediction of reaction direction by comparison of Q of reaction mixture with K of reaction
at given temperature #17.2, 17.4 [ #17.2, #17.4]
Prediction of effect of change of Q, by changing concentration or pressure pp.736-41
[736-40]
Prediction of effect of change of K, by changing temperature of systems at equilibrium
pp. 741-3, [740-1]
Notion that K expressed in concentrations (rather than activities) yields approximate
results, the less concentrated the solution (or gas) the more accurate the prediction.
Equilibria Involving Slightly Soluble Ionic Compounds - #19.3 [#19.3]
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Competition: precipitation vs. complex ion formation #19.4 [#19.4]
Competition: precipitation vs. weak acid formation (Dependence of solubility on pH)
pp.829-32 [829-32]
Calculation of solubilities from Ksp values, common ion effect, prediction whether a
precipitate will form - for 1:1, 1:2 and 1:3 salts #19.3 [#19.3]
Selective precipitation to separate metals p. 840 [pp. 840], precipitation titrations LabEx.4
The Periodic Table and Atomic Structure - Ch 7, 8, pp. 531-41, #14.2
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[Ch.7, 8,
pp. 530-9, #14.2]
General arrangement of table (metals, non-metals, semi-metals)
Names, symbols, atomic number, position in table, and electron configuration of s-block
elements, p-block elements, first transition series, and Ni, Cu and Zn triads.
Periodic physical and chemical properties of elements: melting points, boiling points,
oxidising ability, reducing ability
Quantum mechanical model of atomic structure Ch.7
Electron configuration and chemical periodicit Ch. 8
Periodic atomic properties and rationalisation of - atomic size p.304-6
[308-10], first
and successive ionisation energies p.307-10
[311-14], electron affinity p.310-11
[314-5], electronegativity p.344-6 [347-9], sizes of ions p.318-9 [322-3] - with particular
reference to shielding and “effective nuclear charge” Z eff in rationalisations p.293-4,
[297- ]
Connection between atomic structure and reactivity #8.5 [#8.5]
Main Block Chemistry - Silberberg Ch. 14 and Interchapter p. 529
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Chemistry of s-block elements
Chemistry of p-block elements: commonalities and differences within groups and
between groups. Specific chemistry of Groups 14, 17 and 18.
Periodic trends, such as covalent/ionic character linked to acid/base character of oxides
and hydroxides
Importance of charge-to-radius ratio of cations, polarisation of anions
Diagonal relationships
Hydrogen, a group on its own.
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Course Content continued
Acid-base Chemistry - Silberberg, Ch. 18, 19
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Arrhenius, Lowry-Bronsted and Lewis definitions
Factors affecting acid strength of binary acids, oxyacids
Role of water in ionisation in aqueous solution, self-ionisation of water, Kw, pH, pOH
Ionisation of acids, strong and weak acids
Acid ionisation constant, Ka, base ionisation constant, Kb, relationship between them for
conjugate acid-base pairs
Dependence of pH and percent ionisation on magnitude of Ka (for fixed concentration),
and on concentration (for fixed Ka)
Dependence of [acid]/[base] ratio on pH. Indicator theory
Common ion effect
Acid-base character of salts
pH of polyprotic acid solutions. Acid-base character of intermediate salts of polyprotic
acids in relation to relative extent of acidic and basic reactions. Calculation of pH using
pH = ½(pK1 + pK2)
Titration curves, speciation changes during titration, pH at various points, selection of
indicators
Buffer solutions: design, including selection of conjugate acid-base system; effect of
addition of specified quantities of acid or base; buffer capacity
Thermochemistry and thermodynamics - Silberberg, Ch. 6, Ch. 20
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Constant volume changes and changes of internal energy
Constant pressure changes and enthalpy changes. Standard enthalpy changes
Hess’s Law
Calculation of enthalpy changes using Hess’s Law or by reference to tabulated enthalpy
changes of formation
Bond energies, lattice energies, hydration energies of ions
Qualitative notion of entropy as probabilistic positional dispersion and as energy
dispersion
Entropy of a substance, standard entropy, Third Law of Thermodynamics and indications
of how entropies of substances are estimated
Calculation of standard entropy change of reaction from tabulated standard entropies.
Correspondence between sign and magnitude of entropy change and nature of reaction
Gibbs free energy, free energy changes, standard free energy changes, standard free
energies of formation
Calculation of standard free energy change from tabulated standard free energy changes
of formation, or from standard enthalpy change and standard entropy change - at fixed
temperature
Second Law. Progression from criterion of maximisation of entropy of the universe to
minimisation of free energy of the system. The notion of spontaneity - a property of
reaction mixtures, not of reactions
Independence of criterion of spontaneity and rate of reaction
Relationship between G of reaction and equilibrium constant K
Quantitative estimates of G and K at T  25 C, assuming H and S are constant.
Special reference to dependence of vapour pressure of liquids on temperature.
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Course Content continued
Oxidation-reduction reactions and electrochemistry - Silberberg #4.3 & Ch. 21
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Oxidation and reduction as complementary electron transfer processes.
Oxidation states, balancing oxidation-reduction equations
Electrochemical cells, comparison between spontaneous (Voltaic) cells and nonspontaneous (electrolytic) cells
Cell emf as difference between competitiveness of electrodes for electrons. Competing
reactions of water and dissolved species at electrodes
Cell potentials, standard conditions, standard cell emf, standard half-cell reduction
potentials and arbitrariness of reference point
Nernst equation to calculate cell emf, or half-cell potential, at non-standard conditions
Deducing K from E
Corrosion as an electrochemical process. Factors such as metal fatigue and differential
aeration in determining locations of anode and cathode regions. Protection against,
prevention of
Over voltages in high current electrolysis
Mineral chemistry: principles of extraction of metals from ores.
States of matter - Silberberg Ch. 12
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Comparison of macroscopic properties and sub-microscopic models of gases, liquids and
solids
Changes of state of pure substances: one-component phase diagrams with one solid
phase in relation to vapour pressure of liquids and dependence on temperature; boiling
point and external pressure; vapour pressure of solids and dependence on temperature;
triple point; supercooling; sublimation; melting/freezing point and pressure; critical point
and supercritical fluids
Comparison and use of phase diagrams of water, carbon dioxide and sulfur.
References, Resources and Reading Materials
Recommended Text
M. Silberberg, Chemistry: The Molecular Nature of Matter and Change, 3rd Edition, McGrawHill.
Specific references to the text will be given during lectures. The content of the second edition
of this text is not much different, but there are differences of page numbers and the
numbering of figures and tables.
Unit Web Site
All enrolled students have access to the unit WebCT site (http://webct.uwa.edu.au). This site
will be used for notices, posting of supplementary course materials, email and discussion. It is
strongly recommended that you log onto this site regularly. Students are encouraged to pose
questions about course content on the discussion forum of the site so that all class members
can view and contribute to the discussion.
Assessment Details
Practical work (based on performance in the laboratory as well as reports): 20%
3-hour examination: 80%
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Plagiarism
The University of Western Australia takes very seriously the matter of academic misconduct
by students and has policies in place that define misconduct (including plagiarism) and the
penalties that apply. The consequences for misconduct can be severe, including exclusion
from the university.
All students are expected to make themselves aware of the definitions and policies relating to
academic misconduct, found at the websites below, and with any additional requirements or
stipulations that may be provided by individual unit co-ordinators.
http://www.secretariat.uwa.edu.au/__data/page/20839/StuMiscondInfo.rtf
http://www.teachingandlearning.uwa.edu.au/tl/academic_conduct
When you obtain authority to log in to the unit website, you will see an online module on
academic conduct which you are strongly advised to complete in your own time.
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