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一、热化学方程式1.概念:热化学方程式是表示参加反应的物质的量和反应热的关系的化学方程式。2.意义:热化学方程式不仅表示了化学反应中的物质变化,更重要的是表示了一定物质的量的反应物反应时的能量变化。例如,2H2(g)+O2(g)2H2O(l)ΔH=-571.6 kJ·mol-1表示:在25℃,101 kPa的条件下,2 mol H2和1 mol O2反应生成2 mol H2O时放出571.6 kJ的热。3.要求:①热化学方程式必须和化学方程式一样需要配平。原因是化学反应遵循质量守恒定律。
First, the thermochemical equation 1 concept: Thermochemical equation is to participate in the reaction of the amount of material and reaction heat of the chemical equation. 2. Significance: The thermochemical equation not only expresses the change of the substance in the chemical reaction, but more importantly, the change of the energy of the reactant in response to a certain amount of substance. For example, 2H2 (g) + O2 (g) 2H2O (l) ΔH = -571.6 kJ · mol-1 indicates that 2 mol H2 reacted with 1 mol O2 at 25 ℃ and 101 kPa to generate 2 mol H2O released 571.6 kJ heat. 3. Requirements: ① thermochemical equations must be balanced with the same chemical equation. The reason is that chemical reactions follow the law of conservation of mass.