A spot plate is a device that is typically made with plastic and has circular depressions. It is mostly used in the laboratory for performing small tests on various substances. Most of these tests involve a change in color. It is important to know how to use a spot plate because it is a common component for many biology and chemistry experiments. Spot plates are versatile and can be used for more than one type of test or experiment.
Things You'll Need
- Spot plate
- Chemistry book
- pH indicators
Pour a few drops of each solution in a different row. For example, the experiment may have you test potassium hydroxide, water, and hydrochloric acid. You may put the potassium hydroxide in two wells of the first row, the water in two wells of the second row, and the hydrochloric acid in two rows of the third row.
Put a few drops of one type of pH indicator in the first well of each row. For example, you may use bromothymol blue, which is yellow in solution with a pH of 6.8 or lower; green with a pH from 6.8-7.6; and blue with a pH of 7.6 or greater.
Put a few drops of a second pH indicator in the second well of each row. For example, you may use neutral red, which is blue red in solution with a pH of 6.8 or lower; red orange with a pH from 6.8-8.0; and orange yellow with a pH of 8.0 or greater.
Take notes on the color change that occurs in each of the solution. For example, in the first row, the potassium hydroxide in the first well turned blue and the potassium hydroxide in the second well turned orange yellow. In the second row, the water in the first well turned green, and the water in the second well turned red orange. In the third row, the hydrochloric acid in the first well turned yellow, and the hydrochloric acid in the second well turned blue red.
Draw conclusions about the acidity, basicity, and neutrality of each of the solutions based on the color changes that you observed in the spot plate. For example, since the potassium hydroxide turned blue with the bromothymol blue indicator and orange yellow with the Neutral red indicator, then potassium hydroxide is basic. Since the water turned green with the bromothymol blue indicator and red orange with the neutral red indicator, the water is neutral. Since the hydrochloric acid turned yellow with the bromothymol blue and blue red with the neutral red, hydrochloric acid is acidic.
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