## CHEM1301: Basic Physical Chemistry

**Course Organizer: Dr D M Rowley **

**Lecturers: Dr C G Salzmann, Dr D
W Lewis and Dr D M Rowley**

Normal prerequisite: CHEM1004

Units: 1/2

Moodle page: http://moodle.ucl.ac.uk/course/view.php?id=4553

#### Aims

The aim of this course is to introduce students to gases through the kinetic theory of gases, and to the description and interpretation of chemical systems using quantum mechanics, statistical mechanics, and thermodynamics.

#### Objectives

Students will be able to

- describe real gases in terms of equations of state and virial coefficients
- use the Maxwell distribution to obtain the pressure, the perfect gas equation and Graham's law of effusion
- apply the kinetic theory of gases to collisions between molecules and their consequences in terms of reaction rates
- appreciate the failure of classical mechanics to describe molecular systems, and the role of quantum mechanics in chemistry
- apply the Schrödinger wave equation to translation, vibration, and the hydrogen atom
- use the Boltzmann distribution to describe simple systems and calculate their properties
- apply the principles of thermodynamics, especially the first law, to changes in chemical systems

#### Course Structure

- Lectures:25
- Tutorials:9
- Labs:5 afternoons

#### Assessment

- Exam: 70 % (2 hours)
- Lab: 20 %
- Coursework: 10%

#### Practical course organizer:

Prof N Kaltsoyannis

#### Recommended Texts

- R Silbey and R A Alberty
*Physical Chemistry*3rd Edition John Wiley 2001

An acceptable alternative is:

- P W Atkins and J de Paula
*Atkins' Physical Chemistry*8th edition, Oxford 2006

#### Further Reading

R S Berry, S A Rice and J R Ross Physical Chemistry Oxford 2000

### Course Outline

**Kinetic theory of gases, DMR, 8 lectures**

Experimental observations of gas properties: Boyle's Law, Charles' Law and the work of Avogadro. The ideal gas equation. The model of a perfect gas: it's use in predicting gas pressure and insights into molecular speeds and energies.

Molecular speeds and velocities in the gas phase. The Boltzmann distribution of molecular speeds. Different measures of speeds and velocities of gas molecules.

Collisions between gas molecules and transport properties. Deriving the collision frequency for gas molecules. Collisions between different molecules and an introduction to gas phase kinetics. The simple collision theory for understanding gas phase reaction rates.

Further transport properties. Effusion, and Graham's law. Measurement of vapour pressures. Gas viscosity.

Real gases. Deviations from ideality and the compression factor. Virial equations of state. Condensation. Developing the van der Waals equation of state.

Intermolecular forces. The potential energy of interaction. Disoersive and repulsive forces. The Lennard-Jones potential. Concluding remarks.

**Quantum Mechanics DWL, 8 lectures**

Introduction: Importance of quantum mechanics in chemistry, review of classical mechanics.

Failures of classical mechanics and the wave-particle duality.

The Schrödinger wave equation: principles and simple applications.

Quantum-mechanical treatment of the harmonic oscillator.

Quantum-mechanical treatment of the hydrogen atom.

**Statistical thermodynamics and thermodynamics CGS, 8 lectures**

Distribution of molecular states: number of configurations, gaseous diffusion, real chemical systems, most probable distribution, Boltzmann distribution and Boltzmann factor.

Molecular partition functions: physical interpretation and the fraction of molecules with a particular energy using the partition function, most probable (average) value of energy, effect of temperature.

Vibration: partition function and energy, effect of temperature, mathematical expression for vibrational partition function.

Translation: energy levels, partition function.

Thermodynamics: system and surroundings; heat work and energy; expansion (pV) work, reversible and irriversible processes.

First Law of Thermodynamics: definition; state functions; isothermal expansion and compression of a perfect gas; adiabatic and mechanically isolated systems; calorimetry; enthalpy; heat capacities.