You must want to know these little questions about PH buffers

1. What is pH standard buffer solution? What are its features?

A pH buffer is a solution that keeps the pH level stable. If a small amount of acid or base is added to the solution, or a chemical reaction in the solution produces a small amount of acid or base, and the solution is diluted properly, the pH value of the solution is basically constant. The solution that can resist a small amount of acid or base can be enlarged or diluted, while the pH value does not change is called a buffer solution.

pH standard buffers have the following characteristics:

(1)The pH of the standard solution is known and achieved to the specified accuracy;

(2)The pH value of the standard solution has good reproducibility and stability, with larger buffer capacity, smaller dilution value and smaller temperature coefficient.

(3)The preparation method of solution is simple;

2. How to prepare pH standard buffer solution?

For general pH measurements, a pH kit (250mL can be prepared) can be used. When preparing the solution, deionized water should be used and pre-boiled for 15 to 30 minutes to remove dissolved carbon dioxide. Cut open a plastic bag, pour the reagent into a beaker, dissolve it with appropriate amount of deionized water, rinse the bag, pour it into a 250mL volumetric bottle, dilute to scale, shake well.

3. How to properly store and use pH buffers?

After preparation of buffer solution, should be packed in glass bottle or polyethylene bottle (alkaline pH buffer, such as, pH=9.18, pH=10.01, pH=12.46, should be packed in polyethylene bottle) bottle lid tightly, in the refrigerator at low temperature (5 ~ 10℃) preservation, generally can be used for about six months, such as the mixer turbidity, mildew or precipitation phenomenon, Cannot continue to use. When using, several 50mL polyethylene bottles should be prepared, pour the group flush solution in the large bottle into the small bottle, and place it at the ambient temperature for 1 ~ 2 hours, and then use it after the temperature balance. After use shall not be poured into the large bottle, so as not to pollute, the buffer solution in the bottle in the > Under the environment condition of 10℃, it can be used for 2 to 3 days. The general pH=7.00, pH=6.86, pH=14.00 three kinds of solutions can be used for a longer time. The pH=9.18 and pH=10.01 solutions are easy to change due to the absorption of carbon dioxide in the air.

4. What is the use of pH buffer solution?

(1)Calibrate pH meter before pH measurement.

(2)For example, pH=6.86 and pH=14.00 are used to verify the accuracy of the pH meter. After calibration of the pH meter, the pH electrode is inserted into the pH=9.18 solution to check whether the displayed value of the instrument is consistent with that of the standard solution.

(3)Whether pH meter needs to be re-calibrated in general precision measurement. The pH meter may drift or change after calibration and use, so before the test, the electrode is inserted into the standard buffer which is close to the measured solution, according to the size of the error to determine whether it needs to be calibrated again.

(4)Test pH electrode performance.