《EDTA检测食品中钙的含量.ppt

Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 本任务过程设计为以CaCO3粉末和上次实验所得灰分为样品，测定样品中的含钙量。本实验通过样品的消化将灰化以后的钙转化为溶液中的钙离子状态，将所用的EDTA用钙红试剂进行标定，计算出EDTA的滴定度，再用EDTA来滴定样品，计算出样品的钙离子的含量。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 钙与氨梭络合剂能定量地形成金属络合物，其稳定性较钙与指示剂所形成的络合物为强。在适当的pH值范围内，以氨梭络合剂EDTA滴定，在达到当量点时，EDTA就自指示剂络合物中夺取钙离子，使溶液呈现游离指示剂的颜色（终点）。根据EDTA络合剂用量，可计算钙的含量。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 重点掌握如何根据样品中钙的含量选择EDTA的浓度 掌握本实验中钙红指示剂络合状态及其游离状态时的现象判断 当EDTA从钙红中竞争络合时现象判断 掌握钙标准溶液的配制方法及使用 掌握通过钙标准溶液的浓度来书写实验公式的方法 钙红指示剂的使用特点 柠檬酸钠溶液的作用 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 品名：乙二胺四乙酸(Ethylene Diamine Tetraacetic Acid) 　　简称：EDTA EDTA是化学中一种良好的配合剂，它有六个配位原子，形成的配合物叫做鳌合物，EDTA在配位滴定中经常用到，一般是测定金属离子的含量。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1.25m ol/L氢氧化钾溶液：精确称取70.13 g 氢氧化钾，用水稀释至10 00mL 10g /l.氰化钠溶液：称取1.0 g 氰化钠，用水稀释至100mL 0. 05 m ol/ L 柠檬酸钠溶液：称取14.7 g 柠檬酸钠用水稀释至10 00M L, EDTA溶液：准确称取4.50g E DTA（乙二胺四乙酸二钠），用水稀释至10 00M L, 使用时稀释10倍即可。 钙红指示剂：称取0.1 g 钙红指示剂用水稀释至100m l,，溶解后即可使用。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. C