= Solution
The inferred saturation density is physically implausible for a single molecular layer in the printed units:
$$
A_{\rm molecule}=\frac1{(83.5\times10^{-3})N_A}
\simeq2.0\times10^{-23}\,\mathrm{m^2}
=2.0\times10^{-5}\,\mathrm{nm^2}.
$$
That is far smaller than an atomic cross-section, let alone a butyric-acid molecule. The near-linear reciprocal plot therefore does not validate the physical monolayer interpretation. Possible issues include reported units or normalization, inaccessible/internal area not accounted for correctly, multilayer <adsorption> or other uptake processes. The numbers must not silently be relabelled as micromoles to obtain a more comfortable molecular area.
Back to article page
