Chemistry · Ch 10 — Surface Chemistry
Introduction
Introduction
Why can mosquitoes and other small insects walk on water, yet sink the moment soap is added nearby? Why do water droplets and mercury droplets pull themselves into near-perfect spheres? Why are a butterfly's wings and a lotus leaf's surface non-sticky? Every one of these everyday puzzles comes down to the same branch of chemistry: surface chemistry, the study of processes occurring at the interface between two phases -- solid-liquid, solid-gas or liquid-liquid.
Surfaces matter far beyond curiosities. The bonding between atoms right at a solid's surface differs from the bonding inside its bulk, and that difference drives heterogeneous catalysis, controls the formation and stability of colloids, and governs electrode reactions -- with applications spanning materials science, paints, medicine and biotechnology. Creams, lotions and food products are, at their core, engineered colloids and emulsions.
What this unit sets out to do. By the end of it you should be able to:
- classify adsorption, and distinguish it from absorption;
- explain the Freundlich adsorption isotherm;
- understand catalysis, the characteristics of catalysts, and the theories of catalysis and enzyme catalysis;
- classify colloids, and explain how they are prepared and purified;
- discuss the properties of colloidal solutions, and the role of colloids and emulsions in everyday life.
Irving Langmuir won the 1932 Nobel Prize in Chemistry for his work in surface chemistry. He also invented the gas-filled incandescent lamp and the hydrogen welding technique, and co-discovered the electron-density waves in plasmas now known as Langmuir waves.