How to Tell an Acid From a Base
It is important to be able to distinguish acids and bases in order to fix soil quality, ensure safe drinking water and prevent unstable substances from mixing to form harmful byproducts and noxious gases. Most acidic products have a sour taste, and most bases have a bitter taste, but it is not always safe or practical to taste a substance to determine if it is an acid or a base. Testing the pH of an unknown substance is fairly simple.
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Things You'll Need
- Red cabbage, apple skins or grape skins Blender Boiling water Eye dropper Measuring teaspoon Filter paper pH chart Household ammonia Baking soda Lemon juice Vinegar Cola Cream of tartar Antacid tablets Seltzer water 8 test tubes, beakers or drinking glasses Gloves Eye protection
Instructions
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1
Chop red cabbage, apple skins and grape skins together. Dump into a blender and cover with boiling water. Let stand 5 minutes. Put blender on pulse until cabbage mixture is chopped. Let stand another 5 minutes. Strain liquid into a clean glass jar with a tight-fitting lid. Keep refrigerated when not in use. Allow to stand to room temperature before using.
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2
Pour a little red cabbage solution into each beaker. Add the substance you're testing, one drop at a time. Continue to add a drop of the substance at a time until you notice a color change. Compare the color of your resulting solution to the pH chart.
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3
Make 8 beakers with antacid tablets dissolved in water by crushing an antacid tablet and stirring it into warm water until it disappears. Using an eye dropper, add a drop at a time of one substance into one beaker until you see a reaction. When acids and bases are combined, there is usually a great deal of foam. Be sure to use eye protection and gloves.
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If there is no reaction, the substance being added has the same pH as the antacid, which is a base. Try each of the substances listed at the beginning of this article and note the reactions.
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5
Dip coffee filters into the cabbage solution and lay them on a cookie sheet to dry. Drip each substance onto one of these filters and note any color changes.
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Use the eye dropper to add drops from the substances you identified as bases to the beakers of liquid you identified as acids until the color in the beaker changes back to purple. Mixing an acid and a base results in a neutral. You should also see some foaming action when mixing acids and bases. Keep notes of your results, and graph them on a chart.
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7
Use pH test strips to confirm your results.
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Tips & Warnings
Be sure to use eye protection and gloves when working with chemicals.
