Popularise some knowledge about PH meter
A pH meter measures the acidity or alkalinity of a solution. Most organisms require proper pH levels to maintain life. pH measurements are critical in many areas such as chemical processing, pulp and paper, food, beverages, pharmaceuticals, and more.
What is the main use of your pH meter?
A pH meter is an electronic instrument used to measure the pH of a liquid (special probes are also available to measure semi-solid substances) to confirm the acidity or alkalinity of a substance. A typical pH meter consists of a special measuring probe [glass electrode] connected to a voltmeter that measures and displays the pH reading.
The probe measures the pH of the acidity or alkalinity - the activity of hydrogen ions in the thin-walled glass shell ions around its tip. the pH meter measures and displays the small voltage generated by the probe (about 0.06 pH unit volts).
The pH meter circuit is similar to a voltmeter, but instead of indicating the magnitude of the voltage, it indicates the pH value. Due to the high resistance (20 to 1000 MΩ) characteristic of its glass electrode, the input signal must be very large. Therefore, a simple pH meter circuit usually contains an operational amplifier in an inverting configuration with a total voltage gain of about -17 times. The inverting amplifier converts the small voltage generated by the probe (+0.059 V/pH) into a pH value. In order to display the pH value on the indicator, a further 7 V is usually added to its result, e.g. in a neutral pH solution, the output voltage of the probe is 0 V. The value of the pH meter will be: 0 x 17 + 7 = 7.
In alkaline solutions, the output voltage of the probe ranges from 0 to 0.41V (7 x 0.059 = 0.41). Thus, for a sample with pH = 10 (pH 3 units above the neutral solution), 3 × 0.059 = 0.18 V and the pH meter shows a value of 0.18 × 17 + 7 = 10. In an acidic solution, the output voltage of the probe ranges from -0.41 V to 0 V. Thus, for a sample with pH = 4, -3 × 0.059 = -0.18 V and the pH meter shows a value of -0.18 × 17+ 7 = 4.
