How to prepare pH meter electrode protection solution?
Prepare the 3 mol/L KCL solution for the pH meter. The pH electrode of the pH meter is protected by the protective liquid in the sheath before use. This is to maintain its original pH potential balance and make the measurement more accurate. Here is the protective solution for the PH electrode, which is a 3mol/L KCL solution. Therefore, you must learn how to configure it yourself so that the pH electrode is soaked in the protective solution, so that its activity can be quickly restored and the measurement can be performed well. The following are the steps to prepare the pH meter protection solution - 3mol/L KCL solution:
1. Calculation: The molar mass of KCL is 74.5g/moL, then the mass of KCL=3mol×74.5g/mol=223.5g;
2. Weighing: Use an analytical balance to weigh KCL = 223.5g, and pay attention to the use of the analytical balance;
3. Dissolve: Use 100ml distilled water in a beaker to completely dissolve it, and stir with a glass rod;
4. Transfer and washing: Move the dissolved solution into a 1000ml volumetric flask, use a volumetric flask with a narrow mouth. Note: In order to prevent the solution from spilling and do not let the solution flow down the bottle wall above the scale line, use a glass rod to drain the solution. To ensure that all the solute is transferred to the volumetric flask as much as possible, the beaker and glass rod should be washed two or three times with distilled water, and the solution after each washing should be injected into the volumetric flask. Gently shake the volumetric flask to mix the solution thoroughly. (Use glass rod to drain)
5. Set the volume: When adding water to a point 2-3 cm close to the mark, use a rubber dropper to add distilled water to the mark. When setting the volume, pay attention to the fact that the lowest point of the concave liquid level of the solution is tangent to the scale line, and the eye line of sight is level with the scale line. Do not look down or up, otherwise errors will occur.
6. Shake well: The concentration of the solution after the volume is uneven, plug the stopper of the volumetric flask tightly, hold the stopper with your index finger, hold the bottom of the bottle with the fingers of the other hand, invert and shake the volumetric flask several times , to mix the solution evenly.
7. Shake the diluted KCL solution evenly. Pour the prepared solution into the reagent bottle, cap the bottle and label it. The solution prepared in this way is a 3mol/L KCL solution. Calibration buffers for pH meters also have their own preparation methods, but most of them are bagged reagents, which are simple to configure and can also be purchased on the market.
