Everything You Need To Know About pH Meters
I remember my schools days “if it turns red, it’s acidic, and if it turns blue, it’s alkaline.” I am talking about one of the oldest forms of pH tests. Well, this is a basic test we learn in schools. You compare the color change with the chart and tell how alkaline or acidic something is. Anyway, the readings you obtain from the litmus test is not accurate enough to apply for day-to-day events.
How can you get accurate readings then? You know, the inventors have come up with many instruments to give us accurate measurements. Thanks to them, now we have the pH Meter to tell how something is acidic or alkaline. You can trust the readings you get from the pH Meter to risk your pets and plants.
How does your pH Meter work?: OK, here I am going with the definition I saw on Wikipedia, “The pH Meter measures the difference in electrical potential between a pH electrode and a reference electrode, and so the pH Meter is sometimes referred to as a “potentiometric pH Meter”. The difference in electrical potential relates to the acidity or pH of the solution.”
The principle of operation: By measuring the potential difference between two electrodes, a pH Meter gives us correct readings. The meter has a glass membrane with a known liquid. When the membrane goes into the outside (unknown) liquid, the glass membrane measures the potential of hydrogen. A reference electrode completes the circuit. The meter doesn’t measure the current, only the potential difference.
The solution inside the glass membrane is potassium chloride, which has a pH value of 7 (it’s a neutral solution.) Imagine the unknown liquid is more acidic than the known liquid. Which means; it has more hydrogen ions than the potassium chloride. Immersing the glass electrode in the unknown liquid measures the difference in the voltages produced by the hydrogen ions in the liquids. Well, the instrument measures the voltage difference, but we see the pH value on the display.
How can you get accurate pH readings: Calibrate the pH Meter to get accurate readings. Dip the meter into a solution with a known pH, then adjust accordingly. The temperature affects the meter reading, so now the meters come with a built-in thermometer.
History of the pH Meter: Well, it’s a clever invention. In 1909, German chemist Fritz Haber and his student Zygmunt Klemensiewicz first came up with the glass electrode concept. In 1934, Arnold Beckman, an American chemist managed to get the patent for his “acidimeter.” The first portable pH Meter came out in 1970. The first commercially successful electronic meter came out in 2004.
Types of pH Meters: Since its invention, the instrument has changed considerably. Now, simple pen-like instruments and complex/expensive ones are available. Analog or digital display. Battery powered or line-powered. Well, it depends; buy the meter depending on your requirements.
Some final words: The litmus paper test was one of the oldest methods used for measuring the acidity and the alkalinity of a substance. Anyway, the readings you obtain from the litmus paper is not accurate enough to apply for critical events (it’s good for educational purposes.) Anyway, the pH Meter has filled the gap now.