Determination of sodium hydroxide in sodium hypochlorite solution
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I have a question: when performing central control analysis for sodium hypochlorite, 5 ml of the sample to be tested is taken, 50 ml of distilled water is added, and 2 ml of 30% hydrogen peroxide is added. The starch-iodide test strip shows no color. However, after adding phenolphthalein as an indicator, the solution turns red at first; yet after shaking it for a few seconds, it becomes colorless. Is it because the sodium hypochlorite has not reacted completely? Theoretically, there should be an excess of hydrogen peroxide. I would appreciate guidance from those with more experience; I’m a beginner seeking help
Personal opinion 1: Could it be that the concentration of sodium hydroxide in your sodium hypochlorite is too high?