Indicators can be used to estimate the \(\mathrm{pH}\) values of solutions. To determine the \(\mathrm{pH}\) of a \(0.01 \mathrm{M}\) weak acid (HX) solution, a few drops of three different indicators are added to separate portions of \(0.01 \mathrm{M} \mathrm{HX}\). The resulting colors of the HX solution are summarized in the last column of the accompanying table. What is the approximate \(\mathrm{pH}\) of the \(0.01 \mathrm{M}\) HX solution? What is the approximate \(K_{\mathrm{a}}\) value for \(\mathrm{HX}\) ?

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pK Color of of HIn 0.01 M HX 4.0 Blue Indicator Color Color (HIn) of HIn of In Bromphenol Yellow Blue blue Bromcresol Yellow Purple purple Bromcresol Yellow Blue 4.8 green 6.0 Yellow Green