天然水中碳酸测定有关问题的探讨

Discussion on the Several Questions of the Determination of Carbonic Acid in Natural Water

介绍了天然水体中碳酸的来源、存在形式及平衡关系;指出用“双指示剂”法测定水中碱度的第一终点应显粉紫色,第二终点宜采用甲基红-溴甲酚绿混合指示剂;测定游离二氧化碳要用双样测定并严格控制滴定终点;各种碳酸的含量可与pH值、硬度的测定结果进行校核。

The source, existing form and equilibrium of carbonic acid in natural water are presented in this article, which points out that alkalinity is determined by double indicator that indicates purply at the first terminal point, while at the second terminal point should use methyl red - bromocresol green mixed indicator. Double exponent is applied to determine free state carbon dioxide and the titration terminal point should be controlled strictly. The content of different carbonic acid can be checked with pH value and the determining result of water hardness.