回复vaneblack发表于:2020/7/30 13:57:11悬赏金额:
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大家好:
最近重新阅读了USP <841> Specific Gravity,温故知新,发现有2点不是很理解,想求教各位:
1) Method I中提到“When the monograph specifies a temperature different from 25°, filled pycnometers must be brought to the temperature of the balance before they are weighed.”
问题:若正文的要求不是在25℃,则要求将比重瓶的温度控制到与天平相同温度,然后再称量。这个实际是怎么操作?怎么知道天平的温度?
2)MethodII中提到“Density meters are able to achieve measurements with an error on the order of 1×10–3 g/cm3 to 1×10–5 g/cm3 and a repeatability of 1×10–4 g/cm3 to 1×10–6 g/cm3. For example, an instrument specified to ±1×10–4 g/cm3 must display 0.9970±0.0001 g/cm3 in order to be suitable for further measurement, otherwise a readjustment is necessary.”
问题:是指仪器测定结果的显示屏幕上一定要能显示“0.9970±0.0001 g/cm3”,特别是“±0.0001”?如果不是“readjustment”应如何操作?这个背后隐藏的意思是什么?
求教了,感谢!