How should the electrode protection solution for pH meters be made?
Prepare the 3mol/L KCL solution of the ph meter. The ph electrode of the ph meter is protected by the protective solution in the sheath before use, in order to keep its original ph potential balance unchanged, and to make the measurement more accurate. This is the protective solution of the pH electrode, that is, 3mol/L KCL solution. So you have to learn how to configure it by yourself, so that the pH electrode is soaked in the protective solution, so that its activity can be quickly restored, and it can be measured well again. The following are the steps to prepare the ph meter protection solution - 3mol/L KCL solution:
1. Calculation: KCL molar mass is 74.5g/moL, then KCL mass=3mol×74.5g/mol=223.5g;
2. Weighing: Weigh KCL=223.5g with an analytical balance, pay attention to the use of the analytical balance;
3. Dissolving: use 100ml of distilled water in a beaker to completely dissolve it, and stir with a glass rod;
4. Transfer and washing: transfer the dissolved solution into a 1000ml volumetric flask, and use a volumetric flask with a narrow mouth.
5. Note: In order to prevent the solution from spilling, and at the same time do not let the solution flow down the bottle wall above the scale line, use a glass rod for drainage. In order to ensure that the solute is transferred to the volumetric flask as completely as possible, the beaker and glass rod should be washed with distilled water two or three times, and the solution after each washing should be poured into the volumetric flask. Gently shake the volumetric flask to mix the solution thoroughly. (drainage with a glass rod)
6. Constant volume: When adding water to 2-3 cm close to the scale, use a rubber dropper to add distilled water to the scale. When constant volume, pay attention that the lowest point of the concave liquid surface of the solution is tangent to the scale line, and the line of sight of the eyes is horizontal to the scale line. Do not look down or look up, otherwise it will cause errors.
7. Shake well: the concentration of the solution after constant volume is not uniform, the cork of the volumetric flask should be tightly plugged, and the cork should be held up with the index finger, and the bottom of the bottle should be supported by the finger of the other hand, and the volumetric flask should be turned upside down and shaken several times , to mix the solution evenly.
8. Shake the KCL solution after constant volume. Pour the prepared solution into the reagent bottle, cap the bottle, and label it. This is the 3mol/L KCL solution. The calibration buffer of the pH meter also has its configuration method, but most of them are bagged reagents, which are easy to configure, and these are also available in the market.
