Abstract
In science classes, ammonia is an important substance that is dealt with in various learning situations, so it is meaningful to detect and measure ammonia in student experiments. Concentration of ammonia is generally evaluated by the indophenol method. This method requires phenol and sodium pentacyanonitrosylferrate (III), both chemicals are designated by the Poisonous and Deleterious Substances Control Law. Therefore, when implementing the indophenol method in classes and research activities, it is educationally appropriate to replace it with sodium salicylate, which is safer, or potassium hexacyanoferrate （II）, which is used as a food additive. However, in this measurement method, several types of solutions with different volumes are mixed, so it is an extremely complicated experiment for students. In this study, I investigated the condition of mixing all the test solutions in the same volume so that the experimental procedure could be performed more easily. Specifically, I combined various concentrations of sodium hypochlorite and sodium hydroxide, which greatly affect color development, and determined the concentration range for detecting ammonia.
