分光光度法测定铬和钴的混合物.ppt

,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,分光光度法测定铬和钴的混合物,质量与安全系,分析,3091,班,指导教师：姜洪文,汇报人：刘雅男,学号：,11,2010.12.23,小组成员,组长：刘雅男,组员：郑梦莹 宋世平,郭宏丹 赵海男,葛玥,索 引,一、项目实施依据,二、仪器与试剂,三、分析检验程序,四、数据记录与处理,五、参考资料,一、项目实施依据,当混合物两组分,M,及,N,的吸收光谱互不重叠时，则只要分别在波长,1,和,2,处测定试样溶液中的,M,和,N,的吸光度，就可以得到其相应的含量。若,M,及,N,的吸收光谱互相重叠，只要服从吸收定律则可根据吸光度的加和性质在,M,和,N,最大吸收波长,1,和,2,处测量总吸光度,A,（,M+N,）,1,、,A,（,M+N,）,2,。用联立方程求出,M,和,N,组分含量。,本实验测,Cr,和,Co,的混合物。先配制,Cr,和,Co,的系列标准溶液，然后分别在,1,和,2,测量,Cr,和,Co,系列标准溶液的吸光度，并绘制工作曲线，所得四条工作曲线的斜率即为,Cr,和,Co,在,1,和,2,处的摩尔吸光系数，代入联立方程式中即可求出,Cr,和,Co,的浓度。,二、仪器与试剂,仪器：,752,型紫外可见分光光度计一台,50mL,容量瓶,9,只,10mL,吸量管,2,只,玻璃棒一只,试剂：,0.350mol/LCo,（,NO,3,）,2,溶液,0.100mol/L Cr,（,NO,3,）,3,溶液,752,型可见分光光度计,三、分析检验程序,1,、准备工作,1,）清洗容量瓶、吸量管及需用的玻璃器皿。,2,）配制,0.350mol/LCo,（,NO,3,）,2,溶液：用电子 天平准确称量,10.1860gCo,，用蒸馏水溶解，用玻璃棒移至,50mL,容量瓶中，稀至标线，摇匀，定容。,配制,0.100mol/L Cr,（,NO,3,）,3,溶液：用电子 天平准确称量,4.0015g Cr,，用蒸馏水溶解，用玻璃棒移至,50mL,容量瓶中，稀至标线，摇匀，定容。,3,）按仪器使用说明书检查仪器。开机预热,20min,，并调试至工作状态。,4,）检查仪器波长的正确性和吸收池的配套性。,两个吸收池的吸光度之差要小于,0.5%,，才可配成一套使用。,2,、系列标准溶液的配制：取,4,只洁净的,50mL,容量瓶分别加入,2.50mL,、,5.00mL,、,7.50mL,、,10.00mL 0.350mol/LCo,（,NO,3,）,2,溶液，另取,4,只洁净的,50mL,容量瓶分别加入,2.50mL,、,5.00mL,、,7.50mL,、,10.00mL,0.100mol/L Cr,（,NO,3,）,3,溶液，分别用蒸馏水将各容量瓶中的溶液稀至标线，摇匀，定容。,3,、测绘,Co,（,NO,3,）,2,和,Cr,（,NO,3,）,3,溶液的吸收光谱曲线确定入射光波长,1,和,2,取步骤,2,配制的,Co,（,NO,3,）,2,和,Cr,（,NO,3,）,3,系列标准溶液中各一份，以蒸馏水为参比，在,420700nm,，每隔,20nm,测一次吸光度（在峰值附近间隔小些），分别绘制,Co,（,NO,3,）,2,和,Cr,（,NO,3,）,3,吸收曲线，并确定,1,和,2,。,4,、工作曲线的绘制,以蒸馏水为参比，在,1,和,2,处分别测定步骤,2,配制的,Co,（,NO,3,）,2,和,Cr,（,NO,3,）,3,系列标准溶液的吸收，并记录各溶液不同波长下的各相应吸光度。,5,、未知试样的测定,取一只洁净的,50mL,容量瓶，加入,5.00mL,未知试液，用蒸馏水稀至标线，摇匀，在波长,1,和,2,处测量试液的吸光度,A,（,Cr+Co,）,1,、,A,（,Cr+Co,）,2,。,6,、结束工作,测量完毕关闭仪器电源，取出吸收池，清洗晾干后入盒保存，清理工作台，罩上仪器防尘罩，填写仪器使用记录，清洗容量瓶及其他所用的玻璃器皿，并放回原处。,四、数据记录与处理,420700nm,之间，,Co,（,NO,3,）,2,和,Cr,（,NO,3,）,3,的吸光度,由此确定,Co,（,NO,3,）,2,最大吸收波长是,511nm,，即,1,/nm,420,440,460,480,500,520,540,560,580,600,620,640,660,680,700,A,Co(NO,3,）,2,0.086,0.158,0.277,0.346,0.426,0.424,0.276,0.137,0.080,0.074,0.080,0.086,0.088,0.088,0.088,A,Cr(NO,3,）,3,0.423,0.280,0.150,0.106,0.128,0.192,0.284,0.357,0.370,0.322,0.232,0.147,0.081,0.047,0.021,/nm,490,502,504,505,506,507,508,509,510,511,512,513,A,Co(NO,3,）,2,0.371,0.419,0.426,0.428,0.430,0.432,0.434,0.434,0.435,0.438,0.435,0.433,由此确定,Cr,（,NO,3,）,3,的最大吸收波长是,576nm,，即,2,各溶液在不同波长下的吸光度,0.117 0.106 0.124,/nm,A,Cr(NO,3,）,3,560,0.357,562,0.362,564,0.365,566,0.368,568,0.372,570,0.375,572,0.373,574,0.373,575,0.377,576,0.381,577,578,0.379,0.370,编号,1,2,3,4,Co,（,NO,3,）,2,标液体积,V/mL,2.50,5.00,7.50,10.00,Cr,（,NO,3,）,3,标液体积,V/mL,2.50,5.00,7.50,10.00,A,1,Co,（,NO,3,）,2,0.038,0.286,0.383,0.560,A,1,Cr,（,NO,3,）,3,0.080,0.106,0.117,0.124,A,2,Co,（,NO,3,）,2,0.157,0.138,0.163,0.279,A,2,Cr,（,NO,3,）,3,0.048,0.333,0.491,0.608,未知样在,511nm,的吸光度,平均吸光度,=0.113,未知液在,576nm,的吸光度,平均吸光度,=0.112,编号,1,2,3,A,未知液,0.123,0.109,0.107,编号,1,2,3,A,未知液,0.068,0.069,0.199,工作曲线,由,A=,bC,得,=A/bc b=2cm,求得,Co,511nm,=3.91 L/(mol/L),Cr,511nm,=1.3,L/(mol/L),Co,576nm,=2.04 L/(mol/L),Cr,576nm,=13.75,L/(mol/L),联立方程,A,Co+Cr,511nm=,Co,511nm,bC,Co,+,Cr,511nm,bC,Cr,A,Co+Cr,576nm=,Co,576nm,bC,Co,+,Cr,576nm,bC,Cr,求得,C,Co,=0.014mol/L,C,Cr,=0.005mol/L,五、参考资料,仪器分析（第二版）,黄一石、吴朝华、杨小林 编,仪器分析实验,张济新、孙海霖、朱明华 编,分光光度法,罗庆尧等 编,谢谢观看,