PSCI 1030 ONLINE: LAB 8 Acids and Bases
PSCI 1030 Online Lab 8 Acids and Bases
INTRODUCTION
Today you will be testing to determine whether or not certain substances are acids or bases. In this lab youll be making your own red cabbage indicator by blending it with water and using the liquid. As you add your test chemicals to the cabbage water, it will change colors based on if youre adding an acid or a base. Read over the entire lab procedure below, then complete each task and record your findings in the data section at the end of the lab.
Upon completion, save this document as a PDF with your name in the filename in the form “Yournamehere-acids.pdf” and upload to the assignment box on online campus.
Litmus is a water soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. This is what is normally used for testing acidity, but you will make your own pH indicator solution. 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. Below is a pH scale, with acids being on the left side and bases on the right.
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The strength of the pH scale is determined by the quantity of hydrogen ions (H+), where a high concentration yields a low pH, and a low concentration yields a high pH. The scale ranges from 1 to 14, 1-6 are considered acids, 8-14 are bases, and 7 is neutral.
MATERIALS
You will need the following items:
1. Seven (7) clear plastic cups (or household drinking glasses)
2. A head of red cabbage
3. Water
4. Blender (if you do not have a blender, a cookpot on the stove works too)
5. Strainer (if you do not own a strainer, simply use a few paper towels)
6. Test chemicals:
a. vinegar
b. baking soda
c. lemon juice
d. washing soda (found on the laundry aisle, you can add half a cup to load of laundry after completing the lab)
e. laundry detergent (dont use a colored liquid)
f. soda pop (clear like Sprite® or 7UP®)
g. Alka-Seltzer®
SAFETY
You may want to wear an apron as red cabbage will stain clothing. Safety glasses are optional, if you splash any test chemicals into your eyes promptly flush with water.
PROCEDURE
Red cabbage the natural pH indicator
1. You will need about one cabbage leaf per cup of water. Blend about 5-6 leaves, and 5-6 cups of water in a blender. If you do not own a blender, you can tear up the leaves into small pieces, add to a pan with water, and heat until it turns purple. Let it cool and then you can use.
2. Pour the cabbage/water mix through a strainer to filter out the big chunks, and save the liquid. You can toss the chunky parts.
3. Label your cups with the test chemicals you will be using.
4. Distribute the cage liquid evenly between your cups.
5. Start with vinegar as its a known acid. Add a little to your cup labeled vinegar. Stir and notice the color change. Record your color in the data table. This color indicated you have an acid.
6. In another cup add a teaspoon of washing soda. Record your observation on the data table, this color indicates you have a base.
7. Now experiment with the other test chemicals to determine if they are known acids or bases.
8. Line your test cups up, from 0 to 14, left to right and use your phone to snap a photo. You can email the photo to yourself and upload it in the data sheet.
9. Once complete, the liquids in the cups are safe to be disposed of in the sink with running water.
10. If you used household glasses, be sure and wash thoroughly before using for consumption.
LAB 8 Acids and Bases Data Sheet
