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Secondary IV • 2yr.

Hello again :)

Ok if I have a solution where I have to use colorimetric indicators, how do I use several at the same time to know the pH approximately? Do I simply combine them?

thank you


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Explanations (1)

  • Explanation from Alloprof

    Explanation from Alloprof

    This Explanation was submitted by a member of the Alloprof team.

    Team Alloprof • 2yr.


    It is indeed possible to mix different acid-base indicators in the same solution. You only have to make sure the colors of the two indicators are different so that they can be distinguished from one another when mixed.

    For example, by combining thymolphthalein and methyl orange, the pH can be determined thanks to colours that vary from white, to pale blue, to dark blue in the basic end of the scale and red, to orange, to yellow in the acidic end of the scale.

    In this example, by mixing the two indicators, the color-changing points remain at the same pH, but now the pale blue turns pale green and the dark blue turns dark green.

    Don’t hesitate to write us again!

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