If pH is above the pKa value, the concentration of the conjugate base is greater than the concentration of the acid, and the color associated with the conjugate base dominates.
In your case the [In-] dominates at pH 6 and the solution is red
If pH is above the pKa value, the concentration of the conjugate base is greater than the concentration of the acid, and the color associated with the conjugate base dominates.
pKa = 4.20
pH = pKa log [In-] / [HIn]
In your case the [In-] dominates at pH 6 and the solution is red
This equation shows that when pH equals the pKa value of the indicator, both species are present in 1:1 ratio.
If pH is below the pKa value, the converse is true.
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This post is last updated on hrtanswers.com at Date : 1st of September – 2022