Indicators and the colorations
In chemistry, indicators are often used to determine the pH value of a certain substance. There is always a point at which certain colorations occur.
The determination of the pH value by means of indicators
- Litmus, phenolphthalein or bromothymol blue are used for the normal determination of the pH value. But you can get a more accurate result with universal indicators. These are paper strips that are dipped into the respective liquid or wetted with it.
- Then compare the discoloration of the paper strip with one Color scale. In the end, you can then assess whether the liquid to be tested is an acidic, neutral or alkaline solution. If the stripe changes color in the red to yellow area (0 - 6), it is an acidic solution. If the discoloration is in the green or blue area (8 - 14), it is alkaline. The solution is only neutral at a pH value of seven (pale yellow).
Use in practice - this is how you use the colors
In everyday life there are various reasons to determine a pH value.
- This includes, for example, the pH of the soil in the garden. This is essential if you plan to plant a vegetable patch. For this purpose, there are pH indicators available in stores, often also in hardware stores.
- If you have aquarium fish, you should also consider the pH level. Many fish species can only survive within a limited pH range.
- Acid rain is also a well-known term. These are precipitates which have a high acid number. This is mainly caused by air pollution.
- An interesting experiment is adding lemon juice to black tea. In the beginning, tea is a very dark liquid. However, if you add a little lemon juice, the color turns light brown. As a result of the change in acidity, the colors also change here.
Indicator - a definition of the term
The most commonly used tools in the chemical laboratory include indicators. …
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