|
|
|
|
|
什么是pH值標(biāo)度？
|
pH測量是一種相對測量，它僅僅指示標(biāo)準(zhǔn)溶液與未知溶液之間的pH差別，實際測量時，需要用標(biāo)準(zhǔn)緩沖溶液定期進(jìn)行校準(zhǔn)。因此，為了達(dá)到量值的一致，必須建立pH標(biāo)度。PH標(biāo)度范圍定為0～14pH，pH標(biāo)度的量值由基準(zhǔn)緩沖溶液的pHs值確定。因此，pH標(biāo)度的含義可表達(dá)為：根據(jù)pH定義，在0～14pH范圍內(nèi)選擇若干個pH緩沖溶液作為pH標(biāo)度的固定點(diǎn)，并且采用當(dāng)代技術(shù)能達(dá)到的*準(zhǔn)確的方法測定它們的pHs值。國際上有二種pH標(biāo)度，即多種基準(zhǔn)pH標(biāo)度和單種基準(zhǔn)pH標(biāo)度，中國采用多種基準(zhǔn)pHs標(biāo)度。六種基準(zhǔn)緩沖溶液0～95℃的pHs值見下表：
六種基準(zhǔn)緩沖溶液的pHs值
溫度，℃ | 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 | --- |
|
|
|