【Daily Question】Chemical Engineering Principles 297: Glass Electrode (January 17)

1) Do not expire； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc

What should be noted when using a glass electrode? 1. When using a new pH electrode, it needs to be adjusted by soaking it in distilled water for a period of time to form a proper hydration layer ； The soaking time is related to the glass composition and film thickness; generally, for newly fabricated electrodes as well as those with low glass conductivity and thicker films, a soaking time of 24 hours is appropriate ； Conversely, the soaking time can be shorter. 2. After testing a certain solution, it is necessary to rinse it thoroughly and remove any water droplets before testing the next sample ； 3. During measurement, the bulb of the glass electrode should be completely immersed in the solution, with it slightly above the ceramic core end of the calomel electrode. 4. A magnetic stirrer should be used for stirring at an appropriate speed during measurement; the stirring speed should not be too high, as this can cause bubbles to form on the electrodes and lead to unstable readings ； 5. For samples contaminated with oil, especially those with floating oil, clean them thoroughly using CCI4 or acetone after use. Then rinse them with 1.2 mol/L hydrochloric acid, followed by distilled water. Soak them in distilled water for a day and night before use ； 6. After testing the turbid solution, it should be rinsed thoroughly with distilled water promptly ； 7. There should be no bubbles between the inner electrode of the glass electrode and the bulb; if there are bubbles, gently shake it to allow them to escape.

1) Do not expire； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc ；

1) Do not expire； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc ；

When using glass electrodes, the following points should be noted: 1) Do not use expired electrodes； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc

1) Do not expire； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc ；

Before use, newly purchased glass electrodes must be soaked in distilled water for several hours before they can be employed; after each use, they still need to be immersed in water, as hydration facilitates the diffusion of ions through the glass membrane. In the hydrated gel layer, the diffusion coefficient of monovalent cations is about 1000 times that of dry glass. Therefore, the surface of the glass membrane must come into contact with moisture in order to exhibit good pH electrode performance. With sodium glass electrodes, when the pH is greater than 10, the measured pH value is lower than the actual value; this phenomenon is known as the \"alkaline error\". The cause of the error is the potential response generated by the exchange of alkali metal ions, such as sodium ions, on the glass membrane as well. In strongly alkaline solutions, the hydrogen ion activity is very low; this results in a significant response, thereby causing errors. Since the potential response of sodium ions is the most pronounced, it is referred to as the \"sodium error\". To this end, a lithium glass electrode can be used, which is capable of measuring within the pH range of 0–14, thereby eliminating the \"sodium error\". The typical lifespan of a glass electrode is about one year; after long-term use, it gradually loses its functionality, a phenomenon known as \"aging\". When the electrode coefficient is below 52 mV/pH, it should no longer be used. The membrane of a glass electrode is very thin and prone to breaking; care should be taken to avoid contact with hard objects during use, and the membrane must not be touched by hand. The water droplets adhering to the electrode should be gently absorbed with filter paper; they must not be wiped away. The electrodes must not be washed with solutions containing fluoride ions, sulfuric acid, cleaning solutions, or concentrated alcohol, as this will cause dehydration of the electrode surface and result in its loss of functionality. The operating temperature for glass electrodes is generally 0–50°C; at lower temperatures, increased internal resistance makes measurement difficult.

1. When using a new pH electrode, it needs to be adjusted by soaking it in distilled water for a period of time to form a proper hydration layer； The soaking time is related to the glass composition and film thickness; generally, for newly fabricated electrodes as well as those with low glass conductivity and thicker films, a soaking time of 24 hours is appropriate ； Conversely, the soaking time can be shorter ； 2. After testing a solution, it is necessary to rinse it thoroughly and dry off any water droplets before testing the next sample ； 3. During measurement, the bulb of the glass electrode should be completely immersed in the solution, with it slightly above the ceramic core end of the calomel electrode ； 4. When making the measurement, use a magnetic stirrer to stir at an appropriate speed; the stirring speed should not be too high, as this can cause bubbles to form on the electrodes and lead to unstable readings ； 5. For samples contaminated with oil, especially those with floating oil, clean them thoroughly using CCI4 or acetone after use. Then rinse them with 1.2 mol/L hydrochloric acid, followed by distilled water. Soak them in distilled water for a day and night before use ； 6. After measuring the turbid solution, it should be treated with steam promptly ； 6. After measuring the turbid solution, it must be rinsed thoroughly with distilled water in a timely manner ； 7. There should be no bubbles between the inner electrode of the glass electrode and the bulb; if there are bubbles, gently shake it to allow them to escape.

1) Do not expire； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc ；

1) Do not expire； 2) Prevent the electrode bulb from colliding with objects ； 3) The surface should be free of dirt and rust ； 4) There should be no bubbles remaining between the electrode and the bulb, etc ；