257.在测定烧碱中NaOH的含量时,为减少测定误差,应注意称样速度要快,溶解试样应用无CO2的蒸馏水,滴定过程中应注意轻摇快滴。()

(The third question): 在测定烧碱中 NaOH 的含量时，为减少测定误差，应注意称样速度要快，溶解试样应用无 CO2 的蒸馏水，滴定过程中应注意轻摇快滴。 (A.正确 B.错误) "When determining the content of NaOH in caustic soda, to reduce measurement errors, attention should be paid to fast sample weighing, dissolving the sample with CO2-free distilled water, and during the titration, gentle shaking and fast dripping should be used." (A. Correct) 解析 (Analysis): The answer is correct (A.正确). The question provides guidelines for reducing measurement errors during the determination of NaOH in caustic soda: Fast sample weighing: Ensuring quick and accurate weighing of the sample reduces the potential for errors caused by moisture absorption or evaporation during the weighing process. Dissolving the sample with CO2-free distilled water: Carbon dioxide (CO2) can react with NaOH, affecting the accuracy of the titration. Using CO2-free distilled water ensures that no unwanted reactions occur, providing more reliable results. Gentle shaking and fast dripping during titration: These practices help achieve a smooth and controlled titration process, leading to more accurate endpoint detection and better precision in determining the concentration of NaOH. In summary, these guidelines are aimed at minimizing sources of error and obtaining more accurate results in the analysis of NaOH content in caustic soda.