Academic Year 2020/2021 - 2° Year
Teaching Staff: Alberto TORRISI
Credit Value: 6
Scientific field: CHIM/01 - Analytical chemistry
Taught classes: 21 hours
Exercise: 36 hours
Term / Semester:

Learning Objectives

At the end of the course, the student should be able to calculate the chemical composition of an aqueous solution in presence of Broensted acid-base equilibria and/or complexation equilibria and/or precipitation-solubility equilibria.

Course Structure

Lectures and numerical exercices.

Should teaching be carried out in mixed mode or remotely, it may be necessary to introduce changes with respect to previous statements, in line with the programme planned and outlined in the syllabus.

Learning assessment may also be carried out on line, should the conditions require it.

Detailed Course Content

Introduction - Chemical equilibrium – Equilibrium constant – Factors affecting the equilibrium constant; composition, solvent, temperature. Systematic treatment of equilibrium. Mass, charge and proton balances.

Acid-base equilibria – Broensted and Lewis theories – Conjugate acid-base pair – Strength of acids and bases – Water ionic product and pH – Acidity and neutrality of an aqueous solution - Strong acids or strong bases aqueous solution; rigorous and approximate treatments; criteria and validity limits – Weak monoprotic acids or weak monoacid bases aqueous solution; dissociation degree; rigorous and approximate treatments; criteria and limits of validity – Aqueous solution containing one conjugate polyprotic acid or one polyacid base; rigorous and approximate treatments - Composition vs. pH expression; distribution plot - Aqueous solution containing a conjugate acid-base pair; rigorous and approximate treatments; buffers; buffer capability – Aqueous solution containing a conjugate polyprotic acid - polyacid base pair –– Ampholytes - Aqueous solution containing mixture of acids and bases (strong-strong, weak-strong, strong-weak, weak-weak); rigorous and approximate treatments.

Complex formation equilibria – monodentate and polydentate ligands, chelate effect, partial formation , global formation and conditional formation constants, pH influence.

Precipitation equilibria - Solubility and solubility product - Selective precipitation, gravimetry - Influence of Broensted and Lewis acid-base interaction on the solubility of salts containing monovalent and polyvalent cations and anions.

Activity - Relationship between activity and concentration – Thermodynamic and stoichiometric constants – Ionic strength – Short outline of Debye Hückel theory and its practical application on ionic equilibrium.

Volumetric methods; generality, titration graphs, end-point indicators.

  • Acid-base titrations; strong acid, strong base, weak acid, weak base, polyprotic acid, polyacid base - Titration criteria - Acid-base indicators - Titration error.
  • EDTA complexation titrations; pH choice, auxiliary complexing agents, indicators, titration error – Liebig titration.
  • Precipitation titration: generality - Silver nitrate as precipitation agent - Visualization of titration end-point by Möhr, Volhardt and Fajans methods - Titration error.

Textbook Information

- Daniel Harris - Quantitative Chemical Analysis, 9th edition, W.H. Freeman and Company, New York, 2016

- Douglas A. Skoog, Donald M. West, F. James Holler, Stanley H. Crouch - Foundamentals of Analytical Chemistry, 9th edition, Brooks/Cole, Cengage Learning, 2014