Suitable Indicator: Universal Indicator is a suitable indicator that could be used in this investigation. Universal Indicator is a mixture of several indicators that produces a range of colors at different pH values. It changes color gradually from red at low pH (acidic) to purple at high pH (alkaline). By adding a few drops of Universal Indicator to each of the five substances, the student can observe the color change and determine whether each substance is acidic, alkaline or neutral.
Safety Precaution: The student should wear safety goggles to protect their eyes in case of accidental contact with any of the substances being tested. Some of these substances, such as shampoo, can be irritating to the eyes, and it is important to take precautions to prevent injury.
Fair Test: To ensure that this is a fair test, the student should:
Use the same amount of each substance: The student should measure out the same amount of each substance to ensure that the test is fair and the results are comparable.
Use the same concentration of Universal Indicator: The student should use the same concentration of Universal Indicator for each substance to ensure that the test is fair. This will help to ensure that any differences in color are due to differences in pH, rather than differences in the concentration of the indicator.