Physical Chemistry - CR

Objectives

This subject aims at conferring the students the principles of Physical Chemistry necessary to raise adequate questions to an interpretation of situations to be found in the field of Conservation & Restoration.[1]

Specific objectives are the following: i) quantify chemical equilibrium and fully characterize it in thermodynamic grounds; ii) quantify ion transport in solution; iii) characterize the kinetics of a chemical reaction; iv) understand the principles behind current spectroscopic methods, in particular IR and UV-vis spectroscopies.

In laboratory, the following skills are expected to be developed/acquired: i) design experiments to test a given hypothesis; ii) plan experiments to characterize the kinetics of a chemical reaction or of an ageing process; iii) use UV-vis spectroscopy to characterize compounds and follow reactions.

 

[1] Physical Chemistry is a key subject to other subjects that appear later on in LCR as well as in CR Master courses, e. g., Polymers in Conservation, Diagnostic subjects, Analytical Methods I e II, History and Techniques of Artistic Production).

 

General characterization

Code

10873

Credits

9.0

Responsible teacher

António Jorge Dias Parola

Hours

Weekly - 5

Total - 80

Teaching language

Português

Prerequisites

This subject requires students to be acquainted with basic knowledge in solution chemistry (for thermodynamics and kinetics) and in the structure of matter (for spectroscopy), provided by previous chemistry related subjects of LCR (Principles of Chemistry and Laboratory Security Good Practices (1st semester), Inorganic Chemistry (CR) (2nd semester) and Organic Chemistry (CR) (3rd semester)).

 

Bibliography

P. Atkins, J. de Paula, Elements of Physical Chemistry, 6thEd., Oxford University Press, 2013.

P. Atkins, J. de Paula, Atkins’ Physical Chemistry, 9thEd., Oxford University Press, 2010.

Teaching method

The teaching of Physical-Chemistry is in portuguese, spread over 39 h of theoretical lessons, complemented by 9 h of exercises and problem solving. The experimental part includes 21 h of laboratory practice, where the students prepare an experiment and carry it out.

Students have access to a webpage in CLIP where the experimental protocols, syllabus, exercises, problems, and old exams as well as several data tables are available. 

Evaluation method

Grading of theoretical part (accounting for 60% of the final grade) is done upon three in-class tests  or a final exam. To be successful in the theoretical part, the average of the three tests must be ≥9.5. If not successful through tests evaluation, the theorectical part can be graded though an exam; there is only one exam date.

Grading of the laboratory part (accounting for 40% of the final grade) is done upon reports and question sets relative to experiments (report of T1 to be delivered until 3/10 and the others until mid-18/11, except T5 to be delivered until December) and upon carrying out an experimental mini-project (2 laboratory sessions). The objectives of this mini-project will be given in the first laboratory session. Possible themes for these projects: 1) chemical basis of photography; 2) dyes: natural or synthetic in various supports (textiles, paper, parchment, canvas, glass) and its different uses; 3) inorganic pigments in various supports; 4) other themes suggested and instructed by the student. The mini-project theme must be chosen until the 17/10; the two laboratory sessions concerning this mini-project are scheduled to the weeks of 7/11 and 14/11. The report must be delivered until 31/11. Public oral presentation and discussion of the work will take place on 19/12.

 

Subject matter

1. Revision of concepts acquired in the subject Principles of Chemistry

1.1 Chemical reactions

Spontaneous chemical reactions. Gibbs function. Exoergonic and endoergonic reactions. Chemical equilibrium and its response to changes in experimental conditions. Applications of the concept of chemical equilibrium.

1.2 Electrochemical equilibrium

Thermodynamic properties of ions in solution. Ionic strength. Debye-Hückel law. Electrochemical cells. Nernst equation. Applications: the electrochemical series; solubility constants; measurement of pH, pKa, pX; thermodynamic functions from cell potential measurements; potentiometric titrations.

2. Ion transport and molecular diffusion

Conductivity. Strong and weak electrolytes. Degree of ionization. Kohlrausch’s law and Ostwald’s dilution law. Diffusion. Reference to Fick’s law.

3. Chemical kinetics

Experimental techniques. The rates of reactions. The rate law: rate constant, reaction order. Differential method and integrated rate laws. Half-lives. Reactions approaching equilibrium. Relaxation methods. Dependence of reaction rate on temperature.

Accounting for the rate laws. Consecutive elementary reactions. The rate-determining step. The steady-state approximation. The Michaelis-Menten mechanism. Unimolecular reactions.

4. Molecular spectroscopy

Some important results from quantum mechanics. Electromagnetic radiation and its interaction with atoms and molecules. Molecular symmetry and group theory. Vibrational spectroscopy. Electronic spectroscopy.

5. Basic processes in Molecular Photochemistry

Quantum yields. Excited state lifetime. Bimolecular processes, Ster-Volmer kinetics.

 

In the laboratory:

There is a pool of 8 experimental procedures, 5 of which are each year selected:

T1: Acid-base titration of an anthocyanin followed by UV-vis spectrophotometry. Reds, violets and blues in nature.

T2: Ionic conductivity of weak and strong electrolytes.

T3: Measurement of contact angles in solid-liquid interfaces.

T4: Kinetics of the thermal reduction of toluidine blue with sulfite

T5: Kinetics of the degradation of benomyl in organic solvents

T6: Quantum yield of the photochemical aquation of potassium hexacyanocobaltate(III).

T7: UV-vis spectra of cyanins.

 

There are two laboratory lessons where each group of three students carries out procedures related to a specific problem in Conservation and Restoration.

 

Programs

Programs where the course is taught: