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展开全部H的定义是来自于在等压条件下内能变的时候的一个函数组合.特意用来计算等压下的反应热的.本身没有任何意义.不过是为了计算方便而已.P是压力.整条式子的意思就是某一状态下,具有的焓等于此时的内能+此时的压强与此时的体积的乘积.然后就构造出来了一个函数了.没有什么理解不理解的.因为本身没有意义.只是数学函数的组合,记住就是了,没有必要去理解.当然了,目前是这样.也许未来会发现它的真正物理意义呢.',getTip:function(t,e){return t.renderTip(e.getAttribute(t.triangularSign),e.getAttribute("jubao"))},getILeft:function(t,e){return t.left+e.offsetWidth/2-e.tip.offsetWidth/2},getSHtml:function(t,e,n){return t.tpl.replace(/\{\{#href\}\}/g,e).replace(/\{\{#jubao\}\}/g,n)}},baobiao:{triangularSign:"data-baobiao",tpl:'{{#baobiao_text}}',getTip:function(t,e){return t.renderTip(e.getAttribute(t.triangularSign))},getILeft:function(t,e){return t.left-21},getSHtml:function(t,e,n){return t.tpl.replace(/\{\{#baobiao_text\}\}/g,e)}}};function l(t){return this.type=t.type
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工程热力学思考题答案,第一章_图文第一章基本概念与定义1.闭口系与外界无物质交换，系统内质量保持恒定，那么系统内质量保持恒定的热力系一定是闭口系统吗, 答:不一定。稳定流动开口系统内质量也可以保持恒定。2.有人认为，开口系统中系统与外界有物质交换，而物质又与能量不可分割，所以开口系统不可能是绝热系。对不对，为什么,答:这种说法是不对的。工质在越过边界时，其热力学能也越过了边界。但热力学能不是热量，只要系统和外界没有热量地交换就是绝热系。3.平衡状态与稳定状态有何区别和联系，平衡状态与均匀状态有何区别和联系, 答:只有在没有外界影响的条件下，工质的状态不随时间变化，这种状态称之为平衡状态。稳定状态只要其工质的状态不随时间变化，就称之为稳定状态，不考虑是否在外界的影响下，这是他们的本质区别。平衡状态并非稳定状态之必要条件。物系内部各处的性质均匀一致的状态为均匀状态。平衡状态不一定为均匀状态，均匀并非系统处于平衡状态之必要条件。4.倘使容器中气体的压力没有改变，试问安装在该容器上的压力表的读数会改变吗,绝对压力计算公式，中，当地大气压是否必定是环境大气压, ppp,，()pp,ppp,,()pp,eebebe 答:压力表的读数可能会改变，根据压力仪表所处的环境压力的改变而改变。当地大气压不一定是环境大气压。环境大气压是指压力仪表所处的环境的压力。5.温度计测温的基本原理是什么,上一页下一页

展开全部
H=U+PV ，ΔH=ΔU+Δ(PV)=ΔU+PΔV=ΔU-Wp=Qp，下标p表示等压过程。该式适用于一切无非体积功的等压过程。氮气 H2 生成氨气体积减少，过程中外界大气压压缩反应系统，对系统做功，这种功称为体积变化功，简称体积功，该例中不存在非体积功。非体积功的例子如N2和H2构成原电池系统，过程中电池系统对外界用电器做的电功，常见的非体积功主要是电功，表面张力做功。该例中同时存在体积功（系统中气体体积减少了）。如有不明欢迎追问。
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0:-1;if(n!==r)for(var i=0;i0&&function(t,e,n,r){var i=document.getElementsByClassName(t);if(i.length>0)for(var o=0;o展开全部焓的定义式是：H=U+PV，U是系统的内能，P是外界的压力，V是系统的体积纠正一下，焓变与反应热都与温度差有关，而不只有初始温度。而且，我认为
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