Refrigerants for the 21st Century
A Case-Study General Chemistry Curriculum Supplement
Dr. William Gumprecht
Refrigeration for the preservation of food, blood, human organs and pharmaceuticals and the cooling of living spaces is one of the critical chemical developments of the 20th century. Refrigeration has depended upon refrigerant gases - chlorofluorocarbons - that efficiently carry out therefrigeration cycle.
In 1974, Sherwood Rowland and Mario Molina predicted that chlorofluorocarbon refrigerant gases would reach the high stratosphere and there damage the protective mantle of the oxygen allotrope, ozone. In 1985 we discovered the "ozone hole" over the Antarctic and by 1990 Rowland and Molina's prediction was proved correct. By the time Sherwood and Molina received the Nobel Prize in Chemistry in 1995, we knew how to correct many of the unintended environmental consequences of the refrigerant gases.
This is the story of how industry, government and private citizens worked together, beginning with Rowland and Molina's hypotheses, and long before their predictions proved correct, to fashion new refrigerant gases that should not harm the environment.
These are the refrigerants for the 21st Century
Fluorocarbon Alternatives Concept Map
The story of refrigeration seems to carry nothing but success.
The principles of physics and the science of chemistry combine to offer comfort and convenience - the cooling and freezing of food blood, human organs and pharmaceuticals and the cooling of our living spaces.
And we learn that the chlorofluorocarbon materials that made efficient refrigeration possible seemed to have nothing but attractive properties.
They were available, relatively inexpensive, stable to chemical change, nontoxic and
|We can understand that, over time,
refrigerants escaped from their cooling systems and entered the atmosphere.
So it won't surprise us that in 1973, Prof. James Lovelock reported finding trace amounts of refrigerant gases in the atmosphere. But what basis do we have to worry about this finding? The refrigerants are stable, nontoxic and nonflammable, after all.
|In 1974, Prof. Sherwood Rowland at
the University of California, Irvine was troubled with the thought that the refrigerant
gases would diffuse throughout the atmosphere.
He and post-doctoral researcher Mario Molina applied their knowledge of chemistry and postulated a chain reaction involving the refrigerant gases - a chain reaction that might destroy the important UV-absorbing ozone in the upper atmosphere.
Good science based on the ozone depletion model enabled us to positively identify the ozone hole over the Antractic by 1985.
you do to evaluate Rowland and Molina's unproved thesis in 1974?.
In fact the industrial world responded even to the potential threat. Manufacturers, long before the effect was proved, began to develop refrigerant gases that would not harm our environment .
So today we live in a world in which environmental damage is being slowly abated!
But how do we prevent society's next challenge to the gaseous environment in which we live?
|Concept Maps for this ChemCase||Or move on to|
Principal Investigator Laurence Peterson;
Project Director Matthew Hermes;
Author of this module William Gumprecht.