分析化学专业英语-03.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 　Go down to business. 言归正传。 Closed system allows the transfer of energy (heat) but no mass. 封闭系统允许能量（热）交换，但不允许物质交换。 　Go down to business. 言归正传。 Isolated system does not allow the transfer of either mass or energy. 隔离系统既不允许物质交换，也不允许能量交换。 isolate 　Go down to business. 言归正传。 State function 状态函数 A property of a system that is determined by specifying its condition or its state (in terms of temperature, pressure, location, and so forth). 取决于系统环境或状态（如温度、压强、位置等）的一种性质。 　Go down to business. 言归正传。 The value of a state function does not depend on the particular history of the sample, only depends on its present condition. 状态函数的值与样品的某段历史无关，仅取决于其当前的环境。 　Go down to business. 言归正传。 For example: U, n, T, V and p are said to be state functions - properties that are determined by the state the system in pV = nRT R: molar gas constant (8.314 J?K-1?mol-1) 例如：U，n， T，V和p都是状态函数，它们取决于处于pV = nRT（R：摩尔气体常数，8.314 J?K-1?mol-1）中的系统的状态。 　Go down to business. 言归正传。 Characteristics: 特点 1). When the system’s state is specified, we can give a state function a certain value. 当系统的状态一定时，状态函数有确定值。 　Go down to business. 言归正传。 2). When the system’s state is changed, the value of a state function only depends on its initial state and final state, doesn’t depend on the particular history of the system. 当系统的状态改变时，状态函数值仅决定于系统的始态和终态，而与其某段历史无关。 　Go down to business. 言归正传。 3). When the system comes back to the beginning state, the value of a state function will return to the initial magnitude. 当系统回到开始状态时，状态函数值将恢复到其初始值。 　Go down to business. 言归正传。 Heat and work 热和功 Energy is transferred in two general ways: to cause the motion of an object against a force or to cause a temperature change. 能量以两种基本形式传递：要么使得一个物体克服外力移动，要么使得其温度改变。 　Go down to business. 言归正传。 Heat is the en