During the course of a year, the temperature of your pH samples can vary dramatically. Whether you’re as hot as a sweating stormtrooper on Tatooine, or Luke-warm in a tauntaun on Hoth, how can you be sure your pH measurements are correct?
A water molecule is described in chemistry as H2O or HOH. We could say it is made up of two Hydrogen atoms and one Oxygen atom. But it’s probably more correct to say it is made up of Hs and OHs. You see, pH is the indirect measurement of the ratio of free Hydrogen ions (H) versus free Hydroxyl ions (OH).
To help us understand this, let’s go to a galaxy far, far away. Let’s use the darkside’s Imperial stormtroopers to represent the Hs in the solution and Rebel pilots to represent the OHs in the solution. We can easily see that if there are more rebel pilots on a given planet than there are stormtroopers this must be the location of the rebel base – more OHs in a solution is a “basic” solution. Obviously, going the other way, when the darkside takes over it is a very “acidic” situation.
Now, adding temperature to the equation is quite simple. The planet’s weather conditions have very little to do with the actual ratio of rebels to stormtroopers. However, on a cold planet like Hoth, it’is difficult to count the forces present, because they are dormant in their ice caves trying to stay warm. On a warm planet like Tatooine, everyone is swimming at the pool trying to stay cool. With the right equipment, they are easy to count from orbit in your Corellian cruiser.
In terms of pH, the pH does not change with temperature – only the pH reading. And this pH reading is changed with temperature because of activity of the ions which affects our electronic equipment. To avoid inaccurate readings, there are three simple practices to incorporate into your pH measurements. 1) Automatic temperature compensation (ATC) should be used in the form of a separate probe, built into the pH electrode (triode), or by entering the temperature into the meter manually. 2) If you have auto-buffer recognition, you must be sure to use the correct buffers for that meter, so that the setpoint for any given temperature is correct. 3) Try to avoid large differences in temperature between your calibration buffers and your water sample when possible.
Always remember, unstable or inaccurate pH readings could be caused by unstable or inaccurate temperature readings. And… may the pHorce be with you.