# CHEM30320 Chemical Thermodynamics & Physical Transformations

Building upon physical chemistry topics introduced in earlier years, this module provides a comprehensive presentation of the key concepts in statistical and classical thermodynamics, based on an "atoms first" approach. New concepts are introduced alongside the relevant mathematics, providing a rigorous understanding of thermodynamics concepts, as it applies to chemistry, from first principles. Applications of thermodynamics and physical transformation (e.g. in metallurgy and battery development) and relevant area of emerging research (e.g. the applications of super-critical fluids) are also discussed.

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Curricular information is subject to change

Learning Outcomes:

By the end of this module, you should be able to:
Employ statistical thermodynamics to understand the distribution of molecular states by considering configurations and weights; derive the Boltzmann distribution and use it to predict the populations of states in systems at thermal equilibrium; define what is meant by the molecular partition function, interpret it, and, in certain simple cases, calculate it; describe how thermodynamic information, such as the internal energy or the statistical entropy of a system, may be extracted from the partition function; employ the partition function to obtain any thermodynamic function, for example, the Helmholtz energy, the pressure, the enthalpy, the Gibbs energy, for a system; factorize the molecular partition function into a product of translational, rotational, vibrational and electronic contributions.

Understand the dispersal of energy and the origin of the spontaneity of physical and chemical change; define the property of entropy in thermodynamic terms and describe it from a statistical viewpoint; understand that entropy is a state function; Describe the entropy changes that accompany specific processes such as expansion, phase transition, and heating.

Understand the criteria for spontaneity in terms of the properties of the Helmholtz energy and the Gibbs energy; use the Gibbs energy to express the spontaneity of a process in terms of the properties of a system; use the Gibbs energy to predict the maximum non-expansion work that a system can do; use the fact that the Gibbs energy is a state function to find relations between system properties in terms of Maxwell relations.

Describe mixtures of substances in thermodynamic terms using the class of properties known as partial molar quantities; describe the thermodynamics of mixing; apply the concept of the chemical potential of a substance to describe the physical properties of liquid mixtures; understand how Raoult’s and Henry’s laws may be used to express the chemical potential of a substance in terms of its mole fraction in a mixture; understand the effect of a solute on the thermodynamic properties of a solution, e.g. the lowering of vapour pressure of the solvent.

Describe the use of phase diagrams as a means to discuss the thermodynamic description of the stabilities and transformations of one or more phases; describe the characteristic properties of phase transitions; apply the phase rule to explain phase stability and equilibria between phases for systems involving more than one component; describe the thermodynamic aspects of phase transitions with reference to the dependence of stability on conditions such as temperature and pressure and to the location of phase boundaries.

Execute laboratory experiments involving the construction of simple electrochemical cells and the measurement of equilibrium processes; Calculate relevant physical properties from laboratory experiments, including appropriate propagation of measurement uncertainty; explain the relationship between Gibbs Free Energy and equilibrium; describe the relevance of equilibrium to simple electrochemical systems; use the Nernst equation to predict the energy generated by simple Galvanic cells to extract parameters such as electromotive force and solubility constant.

Indicative Module Content:

Lectures 1 & 2 - The Energy Levels of Atoms and Molecules
Quantization of energy; electronic, translational, rotational and vibrational energies.

Workshop 1: Calculating the Energies of Atoms and Molecules
Calculating electronic, translational, rotational and vibrational energies of systems; expressing energies as wavelengths and wavenumbers, unit conversion in mathematics.

Lectures 3 & 4 - The Boltzmann Factor and Partition Functions Probability; ensemble energy; electronic, translational, vibrational, rotational, molecular partition functions.

Workshop 2 – The Distribution of Energy
Calculating the energies and degeneracies of simple systems; deriving expressions for partition functions. The laws of logs in mathematics.

Lecture 5 & 6 - Statistical Energy & Entropy
System partition functions for solid and fluid systems; statistical (ensemble) molecular energy and the link to internal energy. The third law of thermodynamics, micro- and macro-states, the relationship between absolute entropy and the partition function.

Workshop 3 – Elementary Statistical Mechanics
Using the partition function to determine the internal energy and absolute entropy of a particle or collection of particles; differentiation in mathematics.

Lectures 7 & 8 - The First Law
Heat, work and pressure (classical and statistical); state and path functions; reversible processes; enthalpy; heat capacity.

Workshop 4 – Elementary Classical Thermodynamics
The directionality of heat and work; reversible and irreversible gas expansion, interpreting calorimetry data.

Lectures 9 & 10 - The Second Law
Entropy, and spontaneity, reversible and irreversible heat exchange, entropy temperature dependence, heat flow and heat engines.

Workshop 5 – Entropy Changes in Ideal Gas Systems
The relationship between entropy, enthalpy and internal energy. The relationship between constant volume and constant pressure heat capacity. Integration and partial derivatives in mathematics.

Lectures 11 and 12 – The Helmholtz and Gibbs Energy
Derivation of Gibbs and Helmholtz energies; natural variables; the Maxwell relations; statistical Gibbs and Helmholtz energies. Inequalities in mathematics.

Workshop 6 – Thermodynamic Functions
Manipulating thermodynamic functions under system constraints (isochoric, isothermal etc.), deriving and using the Maxwell relations to determine thermodynamic system changes; second order derivatives in mathematics.

Lectures 13 and 14 - Physical Transformation
Open thermodynamic systems, chemical potential as applied to phase change, chemical potential in mixtures; partial molar quantities; phase diagrams and phase boundaries; Clausius-Clapeyron equation.

Workshop 7 – Phase Diagrams
Interpreting phase diagrams and calculating thermodynamic properties from them; the relationship between the chemical potential of two phases.

Lectures 15 and 16 – Mixtures and Composition
Vapor pressure; Ideal and non-ideal solutions; Raoult and Henry's laws; liquid-liquid solution activity; composition diagrams; mixing energy; liquid-solid solutions; colligative properties.

Workshop 8 – Properties of Solutions
Calculating vapour pressure for liquid-liquid and liquid-solid mixtures; using colligative properties to determine molecular mass.

Student Effort Hours:
Student Effort Type Hours
Lectures

24

Practical

30

Autonomous Student Learning

60

Total

114

Approaches to Teaching and Learning:
A combination of lectures to introduce key concepts, workshops to reinforce and practice the underpinning mathematics, and laboratory sessions to demonstrate how key thermodynamic properties can be measured.
Requirements, Exclusions and Recommendations
Learning Requirements:

CHEM20080 Basis of Physical Chemistry AND CHEM20120 Physical Chemistry (Level 2) of Atoms and Molecules or equivalent

Module Requisites and Incompatibles
Not applicable to this module.

Assessment Strategy
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade
Report(s): Laboratory reports based on discrete experiments conducted in the teaching laboratory. Note: The assessment timing is representative - reports are due one week after the allocated laboratory session. n/a Graded No

30

Assignment(Including Essay): A single homework assignment in which the heat capacity of a material is derived from first principles. n/a Graded No

10

Exam (In-person): Terminal exam. n/a Graded Yes

60

Carry forward of passed components
No

Resit In Terminal Exam
Summer Yes - 2 Hour