※ 引述《leptin323 (leptin)》之铭言： : 设有反应:aP(g)+bQ(g)=cR(g)+dS(g)在定容下反应物p的分压在200度比300度大 : 且使反应容器体积缩小时P莫耳数减少 : 则a+b>c+d,△H>0 : 为何呢谢谢 The main idea behind Le Chatellier principle is merely that the reaction will proceed in the direction that can help restore the system to its initial state when external changes are applied. In the first case, heat is applied to the system when the temperature rises from 200 degrees to 300 degrees, therefore, the reaction will try to consume the heat by working as an endothermic reaction. As stated in the problem, the partial pressure of "P" is larger at 200 degrees. This tells us that the reaction proceeds in the forward direction when temperature is increased. As the first conclusion, we get that the forward reaction is endothermic, which gives us △H > 0. When the total volume is decreased, the pressure of the system will increase if the total mass is held constant. In this case, the reaction will proceed in the direction which can alleviate the pressure by reducing the total number of moles, since they are positively proportional. The problem statement tells us that, when pressure increases, "P" is consumed and thus the reaction moves in the forward direction, and c + d will have to be smaller than a + b in order to result in a reduction in the total number of moles when proceeding in this direction. -- 我的网志： http://www.wretch.cc/blog/appleamily --

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