CHM 122 Mini Experiment – pH of household chemicals Ms Dang Name
Due date: No later than 8AM on November 14th 2012
Total points: 10pts extra credit toward your Quizzes and HW assignment
The pH of a solution can be accurately measured by a pH meter. Although less precise, acid-base indicators are often used to measure pH because they change color with a small pH range. Red cabbage juice contains a natural pH indicator that changes colors according to the acidity of the solution. Red cabbage juice indicator is easy to make, exhibits a wide range of colors, and can be used to make your own pH paper strips
What You Need to Do the Experiment
A head of red cabbage A stove A pot water A medicine cup with teaspoon or milliliter markings Several small paper cups Some test substances (e.g., lemon juice, clear sports drink, lemon-lime soda, window cleaner, vinegar).
Procedure
1. Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage. Place the cabbage in a pot or other clear container and add boiling water to cover the cabbage. Allow at least ten minutes for the color to leach out of the cabbage. (Alternatively, you can place about 2 cups of cabbage in a blender, cover it with boiling water, and blend it.) 2. Filter out the plant material to obtain a red-purple-bluish colored liquid. This liquid is at about pH 7. (The exact color you get depends on the pH of the water.) 3. Prepare a set of 6 household chemical products in a clear cup or small paper cup. If the household product(s) are solid then dissolve them in water before adding the cabbage juice. 4. Add a few (3-4) drops or 1 teaspoon of cabbage indicator to each product and observe the color change.
Report
Write a 1 page summary about this experiment and your conclusion on using cabbage juice as a pH indicator for + those household products. Give an approximation concentration for H3O in each sample. You must include a picture of the result of your experiment. Use the picture below as a reference for pH 1 to pH 14 solution.