pH meter is a tool that can be used to measure the pH of a solution. Electrodes on the pH meter immersed in the solution to be tested pH. pH meter will indicate the pH of the solution automatically.
Working Principle pH Meter
In principle, a pH measurement is based on the electro-chemical potential that occurs between the solution contained in the glass electrode which has been known that there is a solution outside the glass electrode unknown. This is because a thin layer of glass bubbles will interact with hydrogen ions in small and active. The glass electrodes will measure the electrochemical potential of hydrogen ions or termed the potential of hydrogen.
To complete the electrical circuit requires a reference electrode. For the record, the tool does not measure the flow but only measured the voltage. Scheme electrode pH meter will measure the electrical potential between mercury chloride (HgCl) on the electrode and potassium chloride (KCl) which is a solution in the glass electrode and petensial between the solution and the silver electrode.
But the potential between the unknown sample with the glass electrode may change depending on the sample. Therefore, it is necessary to calibrate using other equivalent solution to set the pH value. Calomel electrode consists of a glass tube containing potassium chloride (KCl) which is an electrolyte that interact with HgCl tip KCl solution.
The glass tube is easily broken so as to link it to use porous ceramic or similar substances. Such electrodes are not easily contaminated by metals and elements of sodium. Glass electrode consists of a solid glass tube and connected with thin glass bubble. Dalamnnya contained KCl in the buffer solution pH 7. Electrode silver edges are silver chloride (AgCl2) is connected into the solution.
To minimize unwanted electrical influences, such a device is protected by a layer of protective paper that is usually found on the inside of the glass electrode. In most modern pH meter is equipped with a thermistor temperature, a means for correcting the influence of temperature. Between electrode with glass electrode has been arranged in a single unit.
Maintenance of pH Meter
pH meter must be treated regularly to maintain the service life of the tool. Maintenance includes:
- Battery replacement is done if the layer appears low battery posts
- Cleaning the electrode can be done periodically each of at least 1 week. The cleaning using 0.1 N HCl solution (dilute) by soaking for 30 minutes and then cleaned with DI water.
- When not in use, the main part of the bubble glass electrode must always be in a state of moist. Therefore, it is advisable storage electrode is always soaked with water DA. Storage in a dry position will cause the glass membrane electrode contained in the bubble will be easily damaged and the reading is not accurate.
- When stored, the pH meter must not be at room temperature because the heat will cause the temperature sensor on the tool quickly broken.