Experimental Activity 7 Test of acidity and alkalinity of solution

Experimental Activity 7

Test of acidity and alkalinity of solution

Purpose

1.Preliminarily learn to test the acidity and alkalinity of a solution with an acid-base indicator .

2.Learn how to measure the pH of a solution with pH paper.

Experimental Supplies

Beakers, test tubes, mortars, glass rods, plastic droppers, gauze.

Distilled water, alcohol, phenolphthalein solution, litmus solution, pH test paper, plant petals or fruits, soil samples

Experimental steps

1. Self-made acid-base indicator: choose the petals or fruits of plants by yourself, mash them in a mortar, add alcohol to soak them; use gauze to filter or squeeze out the soaked juice.

2. Select several solutions in the laboratory or in daily life, and conduct the following experiments:

(1) test the acidity and alkalinity of the solution with phenolphthalein solution and litmus solution respectively;

(2) measure the pH of the solution with pH test paper;

(3) Test the color change of the self-made indicator in the solution.

3.Take small soil samples on campus or in fields. The soil sample is mixed with steamed Nuo water in a beaker at a mass ratio of 1 : 5 , fully stirred and left to stand. Measure the pH of the clear liquid with pH paper.

Question and communication

1.your homemade indicator for testing the acidity and alkalinity of solutions ? Learn about the test results of indicators made by other students . Which kind of plant petals or fruits have good test results?

2.Summarize the color changes of self-made indicators in acid and alkali solutions, and communicate with classmates.