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什么是pH值标度？
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pH测量是一种相对测量，它仅仅指示标准溶液与未知溶液之间的pH差别，实际测量时，需要用标准缓冲溶液定期进行校准。因此，为了达到量值的一致，必须建立pH标度。PH标度范围定为0～14pH，pH标度的量值由基准缓冲溶液的pHs值确定。因此，pH标度的含义可表达为：根据pH定义，在0～14pH范围内选择若干个pH缓冲溶液作为pH标度的固定点，并且采用当代技术能达到的*准确的方法测定它们的pHs值。国际上有二种pH标度，即多种基准pH标度和单种基准pH标度，中国采用多种基准pHs标度。六种基准缓冲溶液0～95℃的pHs值见下表：
六种基准缓冲溶液的pHs值
温度，℃ | B1 | B3 | B4 | B6 | B9 | B12 | 0 | 1.668 | --- | 4.006 | 6.981 | 9.458 | 13.416 | 5 | 1.669 | --- | 3.999 | 6.949 | 9.391 | 13.210 | 10 | 1.671 | --- | 3.996 | 6.921 | 9.330 | 13.011 | 15 | 1.673 | --- | 3.996 | 6.898 | 9.276 | 12.820 | 20 | 1.676 | --- | 3.998 | 6.879 | 9.226 | 12.637 | 25 | 1.680 | 3.559 | 4.003 | 6.864 | 9.182 | 12.460 | 30 | 1.684 | 3.551 | 4.010 | 6.852 | 9.142 | 12.292 | 35 | 1.688 | 3.547 | 4.019 | 6.844 | 9.105 | 12.130 | 40 | 1.694 | 3.547 | 4.029 | 6.838 | 9.072 | 11.975 | 45 | 1.700 | 3.550 | 4.042 | 6.834 | 9.042 | 11.828 | 50 | 1.706 | 3.555 | 4.055 | 6.833 | 9.015 | 11.697 | 55 | 1.713 | 3.563 | 4.070 | 6.834 | 8.990 | 11.553 | 60 | 1.721 | 3.573 | 4.087 | 6.837 | 8.968 | 11.426 | 70 | 1.739 | 3.596 | 4.122 | 6.847 | 8.926 | --- | 80 | 1.759 | 3.622 | 4.161 | 6.862 | 8.890 | --- | 90 | 1.782 | 3.648 | 4.203 | 6.881 | 8.856 | --- | 95 | 1.795 | 3.660 | 4.224 | 6.891 | 8.839 | --- |
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