Дата публикации: 2018-05-27 12:34
These are not graded assignments. They are intended only as practice of concepts and vocabulary that are essential to your success in this course. Most of these interactive review activities work well in recent versions of Internet Explorer, Firefox, Chrome and Safari. Most also render perfectly in mobile browsers on higher resolution Android and Apple phones.
In keeping with the framework for AP Chemistry adopted in 7568 - 7569, I am indicating here if the topic to which a review activity relates has been dropped from the curriculum. It will be identified as excluded (Excluded) to indicate that the College Board has specifically excluded it. I will leave the reviews here, however, in case some of you find them useful.
Alkanes undergo few reactions, as the bonds between carbon and carbon and carbon and hydrogen are strong. However, in teh presence of ultraviolet light halogens react directly wth alkanes forming a mixture of products. This can be exemplified by the reaction between methane and chlorine.
It was standing-room only in the lecture theatre last week when we invited prospective undergraduates to a sample Chemistry Lecture. They were attending the University Open Days to find out what it is like to study here.
However, it became apparent that the relative stability of the CFCs was also a problem as they tended to persist in the environment. After diffusing to the upper atmosphere the abundant ultraviolet light caused them to break apart and produce chlorine free radicals.
In this reaction, the chlorine free radical is effectively behaving as a catalyst in that it is regenerated at the end of the reaction. This allows one chlorine free radical to cause the breakdown of hundreds of ozone molecules, before finally meeting another free radical (termination).
It is because of the need to protect the ozone layer that legislation is now in place preventing the use of CFCs in aerosol cans.
This results in free chlorine atoms (free radicals), which are very reactive. These then collide with other particles and cause a chain reaction of the type:
Of course, it is also possible for chloromethane to react in the same way as methane making dichloromethane, trichloromethane and tetrachloromethane. This is typical of free radical mechanisms- there is a mixture of products formed