The detection method of pH in water quality
The pH value generally refers to the hydrogen ion concentration index, which is the negative value of the common logarithm of the hydrogen ion concentration (activity) in aqueous solution, ie -lg[H+]. pH is one of the most important physical and chemical parameters of aqueous solution. All natural phenomena, chemical changes and production processes involving aqueous solution are related to pH. Therefore, it is necessary to measure pH in the fields of industry, agriculture, medicine, environmental protection and scientific research, and the determination is of great significance.
For the determination of pH value, the qualitative method can be determined by using pH indicator and pH test paper, while the quantitative pH measurement needs to be determined by pH meter. Although the detection of the pH value of water quality is very simple, different detection equipment is used in daily life, and the actual operation method is also different.
1. Use a pH indicator
Add a pH indicator to the solution to be tested, different indicators will change color according to different pH, and the pH range can be determined according to the research of the indicator. When titrating, it can be used as an accurate pH standard.
2. Use pH test paper
pH test papers include wide-ranging test papers and precision test papers. Use a glass rod to dip a little of the solution to be tested onto the test paper, and then compare the color change of the test paper with a standard color card to obtain the pH of the solution. The pH test paper cannot show the pH of the oil, because the pH test paper uses hydrogen ions to measure the pH of the solution to be tested, but the oil does not contain hydrogen ions, so the pH test paper cannot show the pH of the oil.
Using pH indicator or pH test paper, this method of water quality ph value is more suitable for individuals or beginners, because the PH value is distinguished by color, which is more intuitive for some people who have no experience in water quality testing.
3. Use a pH meter
A pH meter is an instrument for measuring the pH of a solution. It uses a pH electrode (such as a glass electrode) to measure the pH of the solution. The pH meter can be accurate to two decimal places. With the development of detection technology, pH detection pens and professional pH water quality detection instruments are mainly used at present.
In the daily experimental environment, using a pH detection pen is a good choice, because its measurement results are more accurate and the waiting time is shorter than that of test paper. However, everyone should pay attention to the operation. There are many factors that can affect the pH value of the water quality in the daily environment, so try to avoid it during operation.
For laboratories or professional water quality tests, water quality detectors are used to obtain pH values. These instruments are commonly used as desktop and portable. The advantage of using this professional instrument is that it can obtain accurate pH parameters and a wide range of measured values. It can automatically measure the temperature of water quality and automatically compensate, and the measured value is stable.
