How to read the acidity and alkalinity with pH test paper

When I was studying chemistry in junior high school, there was a chemistry laboratory that used test paper to measure the acidity and alkalinity. The teacher would give each person a test paper, and then drop the liquid to be tested on the test paper, look at the color of the test paper, and then compare the acidity and alkalinity of the liquid with the pH test card. There are also many substances in life that need to measure the acidity and alkalinity, because the acidity and alkalinity are related to our health, so how do you use pH test paper to check the acidity and alkalinity?

1 First, let's briefly introduce the working principle of pH test paper. pH test paper is actually a neutral paper soaked with an indicator that can react with acids and bases to change color. The standard color spectrum is made by adding a solution with a known pH value to the color spectrum, so as to roughly calibrate the pH value of an unknown liquid.

2. Preparation of the test solution: Wash the beaker or glass with pure water and dry it, transfer the test solution into the cup, such as drinking water, vinegar, etc., or prepare the test solution yourself, such as a water solution of soap, shampoo or shower gel, etc.;

3. Detection process: first tear off a strip of pH test paper, take a glass rod, wash and dry it, dip a small amount of the test liquid on one end of the glass rod and drop it on the test paper to observe the color change. Note that it is not advisable to directly insert the test paper into the test solution to avoid contaminating it. Before using the glass rod to dip into another test solution, be sure to wash and dry it again;

4. Comparison process: Compare the color of the test paper with the test liquid added with the standard color spectrum to roughly estimate the pH value of the test liquid to see whether it is within the normal range and whether it will cause harm and pollution to the human body and the environment;

5 One thing that needs to be explained is that although the above-mentioned broad pH test paper can measure liquids with a pH range of 1 to 14, its accuracy is not high. If you need a more accurate value, you can switch to a high-precision pH test paper and measure again based on the approximate pH range of the liquid to be tested to obtain a satisfactory value;

6 Here we would like to provide you with some information about the pH range of human skin, body fluids, etc., as well as the requirements of certain industry standards for the pH range of drinking water, hoping to draw everyone's attention to health. In addition, if you are interested, you may want to test the pH value of drinking water, food and health care products yourself to see if they are healthy for the human body.