信息检索与阅读第二课：松香酸值的标准测定方法.ppt

Alternatively, if an automatic titrator is used, the end point shall be taken either as the inflection point from the plotted curve or pH 10.8 (Note 3) with instruments which titrate to a preset value. 另外，如果使用自动电位滴定仪，终点既可由曲线的拐点来判断，也可以通过仪器滴定到预先设定的pH=10.8来判断。 Note 3 － The value of 10.8 is the average pH encountered at the inflection point by the above procedure using closely controlled conditions, solvent, water ratio, etc. Glass electrodes tend to dehydrate in nearly anhydrous solvent medium. Condition the electrode in water between tests and check with known pH buffers frequently. 注3：pH10.8是上述操作过程在相近控制条件、溶剂、水比例时所得拐点的pH平均值。 玻璃电极在几乎无水的溶剂介质中有脱水的趋势。 在试验中需经常用已知pH值的缓冲液在水中校正电极。 12. Calculation and Report 12.1 Calculate the acid number as described in Section 7, and report to the nearest whole number. 12 计算和报告 12.1 根据第七部分计算酸值，结果取整数。 * Designation：D465－82 (Reapproved 1997)?1 Standard Test Methods for Acid Number of Rosin1 名称： D465－82 (1997年重新核准) 松香酸值的标准测试方法 第五讲 学习目标 掌握：有关酸碱滴定方面的专业词汇； 熟悉：松香酸值测定的两种标准方法；翻译课文； 了解：松香酸度的标准测试方法的原理；并能够借助词典阅读相关的英文文献。 New words and expressions rosin acid number internal indicator method potentiometric method glass electrode alkali isopropanol 松香，树脂 酸值，酸度 内指示剂法 电位(势)法 玻璃电极 碱 异丙醇 n- 正； iso- 异； sec- 仲； tert- 叔 phenolphthalein thymol blue erlenmeyer flask normality stirring paddle standardization borax 酚酞 百里酚蓝 厄伦美厄烧瓶（锥形瓶） 当量浓度 搅拌桨 标准化 硼砂 New words and expressions New words and expressions buffer beaker volumetric flask buret inflection point 缓冲液 烧杯 容量瓶 滴定管 拐点 New words and expressions designation jurisdiction purport lump grind titrate automatic titrator 名称，指定 权限 声称 块 碾，磨 滴定 自动滴定仪 This standard is issued under the fixed designation D 465: the number immediately followed the designation indicate the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year 上标