Thursday, March 5, 2020

Working Principle and Procedure of pH Meter


What is the pH Meter?
A pH meter is an automated measurement tool used to determine the pH of the liquid. A rough idea of pH can be achieved using indicators, pH papers or litmus papers that change color based on the pH level. Such types have limits on their precision, and it can be difficult to interpret correctly. A pH meter consists of an electrode that is attached to an electronic meter that monitors and displays the correct pH reading.

Working Principle of pH Meter
The pH meter mainly works on the assumption that the interface between two liquids produces an electric potential that can be determined. The working principle of pH meter relies on the exchange of ions from the liquid sample through the glass membrane to the inner solution of a glass electrode. The porosity of the glass membrane decreases with constant use, which reduces the probe's performance.

Types of pH Meter
The pH meter ranges from easy and economical pen-like apparatus with computer interfaces and complex and costly laboratory apparatus, in which many inputs are recorded for indicators and temperature measurements to manage the variation in pH due to temperature. The display may be digital and the systems may be operated by batteries or depend on the electric power. 

There are special pH meters that can be used in particular applications that allow pH determination colorimetrically. Commercial pH meters are available based on solid-state electrodes, instead of traditional glass electrodes.

Process of pH Meter
Before beginning a pH meter process, we must recognize the various parts essential to perform the process. A pH meter consists of three major parts such as pH electrode or glass electrode or combined electrode, temperature probe, and electronic control unit.
pH Electrode: Glass electrodes are the most widely used pH electrodes made of special glass. Silver/silver chloride (Ag / AgCl) is the most regular reference electrode form used today.
Temperature probe: For accurate determination of pH, some pH meters automatically compensate for temperature. This is achieved by a meter, temperature probe, which, along with the electrode, is submerged in the sample solution.
Electronic control unit: To produce a chemical signal, the electrode responds to the concentration of hydrogen ions in the sample solution. This signal is then transformed into pH values shown on the screen.

Procedure for pH measurement
The pH meter should be calibrated with the appropriate buffer solution such as pH 07.00, 04.00, and 09.20 to confirm the performance of the pH electrode before pH measurement. The process may look a little variation depending on the pH meter used and the electrode used however in most cases the pH determination process is very similar.
  • Clean the electrode and temperature probe with deionized water and wipe gently with soft tissue paper.
  • Immerse the electrode in the sample solution.
  • Press the pH mode key which is on the board.
  • The instrument will display the pH.
  • Save the reading or print the reading if the printer is connected.
  • Reset the instrument and again clean the electrode and temperature probe with distilled water and wipe gently with soft tissue paper.

Applications of pH Meter
  • The basic application of pH meter allows us to determine if any liquid sample is acidic or basic or neutral.
  • The pH used mainly in the pharmaceutical, beverage, chemical and food industries.
  • It is commonly used in chemistry to determine the acidity or basicity of a substance.
  • It is used in production to ensure product quality.
  • The pH is widely used in the development and research in many fields.
  • The pH is very significant for checking the consistency of water, soil, and pesticides in the agricultural sector.
  • The pH meter is an improved version for pH determination than traditional methods, providing simple, accurate pH.

The Advantages of pH Meter are as Follows.
  • This makes pH measurement quick and simple.
  • The advantage of the pH meter is that they are compact and portable (Pen pH meter) you can use at a different location.
  • It can be used for a wide variety of applications.
  • This indicator gives an accurate pH value compared to pH paper, and indicators.
  • It covers the entire range of pH i.e. 01 to 14.
  • With a standard buffer solution, you can calibrate the pH meter to improve consistency.

The Disadvantages of pH Meter are as Follows.
  • Deposition on the electrode membrane can cause an error in the results.
  • Because of fragile glass electrodes, there is a risk of breakage.
  • It is often necessary to calibrate the pH meter.
  • To calibrate the pH meter you need buffer solutions that make it expensive.
Commonly asked questions on pH meter are as follows.

What is a pH meter?
A pH meter is an apparatus used to determine the acidity or alkalinity of a solution. The pH is a measure of hydrogen ion concentration.

What is the basic principle pH meter?
A pH meter gives information for how acidic or alkaline a solution is. Measuring the concentration of hydrogen ions is the basic principle of the pH meter.

Difference between pH meter and pH paper
The main difference between a pH meter and a pH paper is that a pH meter determines the exact pH value, whereas a pH paper does not give an exact pH value.

Why do you need to calibrate a pH meter?
To prevent drift and maintain the accuracy of pH meter, it is necessary to periodically calibrate the pH.

Why are Buffer Solutions used to calibrate the pH meter?
The buffer solutions are used to calibrate a pH meter as they avoid changes in pH. You can adjust the value of pH by using the standard buffer solution of known pH.

Difference between conductivity meter and pH meter 
The main difference between conductivity meter and pH meter is that the conductivity meter is used to find out the conductance (electric current) of a liquid sample and pH meter uses to find out the concentration of hydrogen ion in a liquid sample.


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