How do I prepare the protective solution for the electrodes of a pH meter?
The pH electrode of the 3mol/L KCL solution pH meter is protected by a protective solution in the sheath before use, in order to maintain its original pH potential balance and ensure more accurate measurement. Here is the protective solution for the pH electrode, which is a 3mol/L KCL solution. So you need to learn how to configure it yourself, soak the pH electrode in a protective solution, so that it can quickly restore its activity and measure well. The following are the steps for preparing pH meter protective solution -3mol/L KCL solution:
1. Calculation: If the molar mass of KCL is 74.5g/moL, then the KCL mass=3mol × 74.5g/mol=223.5g;
2. Weighing: Use an analytical balance to weigh KCL=223.5g, pay attention to the use of the analytical balance;
3. Dissolve: Dissolve completely in 100ml of distilled water in a beaker and stir with a glass rod;
4. Transfer and wash: Transfer the dissolved solution into a 1000ml volumetric flask with a thinner opening. Attention: To prevent the solution from spilling out and not to let the solution flow down the bottle wall above the scale line, use a glass rod to drain the water. To ensure that all solutes are transferred to the volumetric flask as much as possible, the beaker and glass rod should be washed with distilled water two or three times, and the solution after each wash should be injected into the volumetric flask. Gently shake the volumetric flask to thoroughly mix the solution. (Use a glass rod for drainage)
5. Constant volume: When adding water to a depth of 2-3 centimeters close to the mark, use a dropper with a rubber head to add distilled water to the mark. When setting the volume, it is important to note that the lowest point of the concave liquid surface of the solution should be tangent to the scale line, and the line of sight of the eyes should be horizontal to the scale line. Do not look down or up, otherwise it will cause errors.
6. Shake well: If the concentration of the solution is uneven after reaching a certain volume, the stopper of the volumetric flask should be tightly sealed. Use your index finger to hold the stopper, and use the fingers of your other hand to hold the bottom of the flask. Invert and shake the volumetric flask multiple times to mix the solution evenly.
7. Shake the KCL solution to a constant volume. Pour the prepared solution into a reagent bottle, cap the bottle with a stopper, and label it. The resulting solution is a 3mol/L KCL solution. The calibration buffer for pH meters also has its own configuration method, but most of them are bagged reagents with simple configuration, which can also be purchased in the market.
