Interdependence. Interdependence is a key idea in science. As students learn about science, they begin to understand that the earth is not a group of discrete parts but a continuous environment existing over time as well as place.
In order to remove the caffeine from coffee beans, the beans are washed in a solvent (a liquid capable of dissolving substances), transferring the caffeine from bean to liquid in a process known as extraction. To extract caffeine from whole coffee beans, the following solvents can be used:
Then the beans are removed and either dichloromethane or ethyl acetate is used to extract the caffeine from the water. As in other methods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. An equilibrium is reached after several cycles, wherein the water and the beans have a similar composition except for the caffeine.