计算题：取水样50ml，用0..0500mol/LHCl溶液滴定测碱度，当酚酞由红色转为无色时，消耗滴定液0.65ml，用甲基橙作指示剂继续滴定，当溶液由黄色转为红色时，又消耗滴定液4.19ml，试计算判断该水样中的碱度成分含量及总碱度值。
参考答案：
解：令P为酚酞碱度，M为甲基橙碱度。
P=（0.05×0.65×103）/50=0.65（mmol/L）
M-P=（4.19×0.05×103）/50=4.19（mmol/L）因为M-P＞P，所以水样中仅有CO和HCO两种碱度成分。
C（1/2CO）=2P=2×0.65=1.3（mmol/L）
C（HCO）=（M-P）-P=4.19-0.65=3.54（mmol/L）
即M=4.19+0.65=4.84（mmol/L）
水样中仅有CO和HCO两种碱度成分，浓度分别为1.3mmol/L，3.54mmol/L，总碱度为4.84mmol/L。
| 完形填空。 This year is World Conservation (保护) Year. The United Nations wanted everyone to know that the world is 1 . They hoped that the governments would act quickly in order to conserve 2 . Here is one example of the problems. 3 there were 1,300 different plants, trees and flowers in Holland but now only 866 remain. 4 have been destroyed by modern man and his technology. We are changing the earth, the air and water, and everything that 5 and lives. We can't live without these things. If we continue to do things 6 this, we shall destroy ourselves. What 7 in the future? Perhaps it is more important to ask "What must we do now?" The people who will be living in the world of tomorrow 8 the young of today. A lot of them know that conservation is necessary. Many are helping to 9 . They plant trees, build bridges across rivers in forests and so on. In a small town in the United States a large group of girls cleaned the banks of 11 kilometers of their rivers. Young people may hear about conservation through 10 called "No one's going to change our world." It was made by the Beatles, Cliff Richard and other singers. The money from it will help to conserve wild animals. | ||||
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