Electrophoretic mobility of the anionic form A2 of the weak acid phenol $(\mathrm{HA}=C_6{H}_5\mathrm{OH})$and its derivatives are:

(a) Explain the trend in electrophoretic mobility from phenol to 4-methylphenol to 4-ethylphenol.

(b) Predict the electrophoretic mobility of the analytes at pH 10.0. Explain why the predicted mobility differs from mA2. (c) The electroosmotic mobility is toward the cathode and greater in magnitude than the analyte electrophoretic mobilities. In what order will the peaks appear in the electropherogram at pH 10.0?

The electrophoretic flow of the compound depends on its charge and in contrast to its magnitude and viscosity of the medium.

Electrophoretic mobility is the response of the solute to the applied electrical field.

There are two factors that affect electrophoretic mobility:

(1) Charge - higher charge = higher electrophoretic mobility.

(2) Size - bigger molecules = lower electrophoretic mobility.

(a)

$\mu$depends on the analyte size, the bigger the molecules the lower is electrophoretic mobility.

(b)

Atthe electrophoretic mobilities would be$\mathrm{\mu }\left(\mathrm{phenol}\right)=-1.53\times {10}^8$

$\mathrm{\mu }\left(\mathrm{trichlorophenol}\right)=-2.85\times {10}^8$

Where only a fraction of HA would be ionized - therefore the electrophoretic mobility would be a fraction of$\mathrm{\mu }\left(\mathrm{A}\right)$

(C)

This is the order the peaks appear in the electropherogram at

$4-\mathrm{ethylphenol}=4-\mathrm{methylphenol}<\mathrm{phenol}<\mathrm{trichlorophenol}$