Air-Conditioning, the Ozone Hole, and Technology

we consider something that directly affects more of us than DNA testing—the chemicals used as refrigerants. The development of refrigerants is rooted in some interesting history of chemistry. Refrigeration as we know it 

An abstract picture of how DNA unravels and is reproduced. In this way, a parent s DNA is passed to the offspring. (More information about how this happens is given in Section 15.11.) 

FIGURE 1.1 The natural sciences, with some of their subdivisions. The number of subdivisions continues to increase as the boundaries between the sciences disappear. 

To a chemist, a stabie substance is one that is not easiiy changed into something else. Water is a stable substance. 

Ozone is a gaseous pollutant at low altitudes in our atmosphere (Section 4.7). 

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