pH Error as a Function of Temperature |
pH measurement error due to temperature is a function of both the temperature and the pH value being measured, as illustrated in the table below.
At a pH of about 7, there is no error due to temperature. Similarly, at a temperature of 25°C, there is no error at any given pH value.
However, the more the temperature changes from the ambient calibration temperature and the more the pH departs from 7 (in either direction), the greater the pH error becomes.
| pH Temperature Error Table | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Temp/pH | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| 5°C | .30 | .24 | .18 | .12 | .06 | 0 | .06 | .12 | .18 | .24 | .30 |
| 15°C | .15 | .12 | .09 | .06 | .03 | 0 | .03 | .06 | .09 | .12 | .15 |
| 25°C | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 35°C | .15 | .12 | .09 | .06 | .03 | 0 | .03 | .06 | .09 | .12 | .15 |
| 45°C | .30 | .24 | .18 | .12 | .06 | 0 | .06 | .12 | .18 | .24 | .30 |
| 55°C | .45 | .36 | .27 | .18 | .09 | 0 | .09 | .18 | .27 | .36 | .45 |
| 65°C | .60 | .48 | .36 | .24 | .12 | 0 | .12 | .24 | .36 | .48 | .60 |
| 75°C | .75 | .60 | .45 | .30 | .15 | 0 | .15 | .30 | .45 | .60 | .75 |
| 85°C | .90 | .72 | .54 | .36 | .18 | 0 | .18 | .36 | .54 | .72 | .90 |