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目的评估水中总硬度质量浓度测量结果的不确定度。依据GB/T5750.4-2006生活饮用水标准检验方法。方法吸取水样50.0 ml,置于150 ml锥形瓶中,加入2 ml缓冲溶液,5滴铬黑T指示剂,立即用Na2EDTA标准滴定溶液滴定至溶液由紫红色变成纯蓝色为止。同时做空白试验,记下用量。(实验室温度在20℃±5℃)。结果生活饮用水中总硬度为444.8 mg/L,U=8.284 8 mg/L,k=2。结论乙二胺四乙酸二钠滴定法测定生活饮用水中总硬度的不确定度为总硬度444.8 mg/L,U=8.284 8 mg/L,k=2。
Purpose To assess the uncertainty of the measurement results of total water hardness. According to GB / T5750.4-2006 standard test methods for drinking water. Methods Pipette 50.0 ml of water into a 150 ml Erlenmeyer flask. Add 2 ml of buffer solution and 5 drops of chrome black T indicator. Immediately titrate with Na2 EDTA standard titration until the solution turns from purplish red to pure blue. At the same time do a blank test, note the amount. (Laboratory temperature at 20 ℃ ± 5 ℃). Results The total hardness of drinking water was 444.8 mg / L, U = 8.284 8 mg / L, k = 2. Conclusion The uncertainty of the total hardness measured by disodium edetate titration in drinking water is 444.8 mg / L, U = 8.284 8 mg / L, k = 2.