Effects of Added NaCl Counterion

Examples of log-log plots of NaCl concentrations with corresponding CMC values at 20°C of NaTC, NaTDC, and NaTC/NaTDC mixtures are shown in Fig. 40. The effects of increasing counterion concentration can be summarized as follows  

Below an extrapolated NaCl concentration of 0.7 AI the slope of the log CMC/log NaCl plots are practically horizontal. Above this salt concentration (not shown in Fig. 40, but see Table IX) a steep fall in the log CMC occurs with a slope of 45°. 

This bile salt was studied only up to 0.6 M NaCl due to insolubility in higher NaCl concentrations. The log-log plots lie nearly on straight lines with negative slopes of 23 °. 

Except for the CMC in 0.8 M NaCI (see Table XI) the points lie on a line with a slope of 18°. The CMC at 0.8 M NaCl is well below the curve extrapolated from lower NaCl concentrations. 

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