Standard addition. A particular CO2 compound electrode like the one in Figure 14-28 obeys the equation E = constant - [βRT (ln 10)/2F] log[CO2], where R is the gas constant, T is temperature (303.15 K), F is the Faraday constant, and β = 0.933 (measured from a calibration curve). [CO2] represents all forms of dissolved carbon dioxide at the pH of the experiment, which was 5.0. Standard additions of volume VS containing a standard concentration cS = 0.020 0 M NaHCO3 were made to an unknown solution whose initial volume was V0 = 55.0 mL.


Prepare a graph with Equation 14-15 and find [CO2] in the unknown.