Complete these exercises after reading the experiment but before coming to the laboratory to do it$.$

The data graphed in Figure $4\mathrm{.}1$ were collected for the indicator phenolphthalein. This indicator is colorless at intermediate $pH$ values and becomes magenta at high $pH.$ The absorbance spectra of a series of solutions of phenolphthalein at different $pH$ values is shown in the figure.

Figure $4\mathrm{.}1$ Changes in the absorbance spectrum of phenolphthalein at different $pH$ values.

For the four intermediate $pHs$ in the graph, determine the value of the fractional ionization $$ of HA at the pHs listed. Use these values to determine four independent values for $K_a.$ Present your data by filling in the following table.

$\backslash$table$[[pH,A^{550},,K_a$