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The effect of temperature on pH

by:BOQU     2023-03-26
PH electricity, the influence of temperature Each pH is 0.003PH/°C, for example, a 0.2-grade PH meter is calibrated in a 30°C pH7. 8 and PH7.00 differ by one PH unit), then the maximum error affected by temperature is 300.003=0.09PH. If it is 3 PH units (in the range of PH4~10), the maximum error is 0.27PH, from which it can be seen that the temperature has a great influence on the pH. Of course, we can also draw conclusions from it. In order to reduce the error of temperature on pH measurement, we should pay attention to the following three points: ①Try to choose a buffer solution close to the pH value of the measured solution to calibrate the pH meter. ②Try to make the temperature of the calibration solution consistent with or close to the temperature of the measured solution. ③ A pH meter with temperature compensation should be selected. PH meters with an accuracy higher than 0.1PH have temperature compensation adjustments, while PH meters with a precision of 0.2 have no temperature compensation. Some 0.2-grade PH meters also claim to have 0.1-grade precision, but this is actually impossible. Some people confuse the two concepts of resolution 0.1PH and precision 0.1PH. Even in terms of a pH unit, the pH error at a distance of 60°C is 0.00360=0.18PH. Therefore, the high accuracy of a pH meter without temperature compensation is only 0.2PH. Our PH online analyzer adopts the glass electricity method, which uses glass electricity as the indicator electricity and saturated calomel electricity as the reference electricity to form a battery. Under the ideal condition of 25C, the hydrogen ion activity changes by 10 times, causing the electromotive force to shift by 59.16mv. Our PH online analyzer can also add a temperature compensation device to facilitate the correction of temperature differences, for routine water sample monitoring, and the resolution can reach 0.01pH. In order to improve the accuracy of the measurement, the pH value of the standard buffer solution selected when calibrating the instrument should be close to the pH value of the water sample.
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