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选修4第一章《化学反应与能量》,在新课标全国卷中年年重复出现,运用盖斯定律计算反应热,属于高考的新增热点之一,能量变化图像是近几年高考命题的常见形式,热化学方程式的书写和对基本概念的辨析是高考命题的重点。下面举例透析这部分学习要点,供同学们学习时参考。一、反应热与化学键的键能的关系1.化学反应的过程:化学键的断裂与形成的过程。反应物分子的化学键断裂要吸收能量,生成物分子的化学键形成要放出能量,化学键的断裂与形成是物质在化学反应中发生能量变化的主要原因。
Elective 4 Chapter I, “Chemical Reactions and Energy,” reappears year by year in the New Curriculum Reforms, using Gass’s Law to calculate the heat of reaction is one of the new hot spots in the college entrance examination. The images of energy changes are the subjects of college entrance examination in recent years The common form of thermochemical equation writing and discrimination of the basic concepts is the focus of college entrance examination proposition. The following example dialysis this part of the learning points for students to learn reference. First, the heat of reaction and the bond energy bond The relationship between the chemical reaction process: the bond breaking and forming process. Reactants molecules to break the chemical bond to absorb energy, the formation of the chemical bond molecules to release energy molecules, the chemical bond breaking and formation of the material in the chemical reaction occurs in the main energy changes.