= Ideal-solution vapor-liquid equilibrium test
The <Mixture measurements and the Gibbs-Duhem constraint> article describes the inspected <acetone>–<chloroform> preparation, apparatus, paired readouts, controls and sampling limits.<Liquid-Vapor Equilibrium of a Binary System by James M. McCormick>[Procedure, Figure 1, Tables 1–2: apparatus, calibration, pure-component control, successive additions and paired sampling]{ref}
That existing apparatus account supplies the experimental controls and limitations. Its <refractive index> calibration yields <mass fractions>, which must be converted to <mole fractions>. For a measured component-A <mass fraction> $w_A$ and component <molar masses> $M_A,M_B$,
$$
x_A=\frac{w_A/M_A}{w_A/M_A+(1-w_A)/M_B}.
$$
Apply this conversion separately to the flask sample and to completely condensed <vapor> to obtain $x_A$ and $y_A$. Comparing $y_iP$ with $x_ip_i^*(T)$ tests <Raoult's law> at the measured <temperature>; using the changing <temperature> at each composition is essential. The chosen A/B values above are unrelated to the protocol's substances.
The more general diagnostic, retaining an <ideal gas> <vapor> and negligible pure-<liquid> <pressure> correction, is
$$
y_iP=x_i\gamma_i p_i^*(T),\qquad
\gamma_i\simeq\frac{y_iP}{x_ip_i^*(T)}.
$$
This follows by replacing $\ln x_i$ with $\ln(x_i\gamma_i)$ in the <chemical potential> subtraction used for <Raoult's law>. A reproducible discrepancy from $\gamma_i=1$ can expose failure of the <ideal solution> approximation, but interpreting it requires checking <measurement uncertainty>, representative paired sampling and the <ideal gas> approximation. Apparent agreement within uncertainty supports an approximation over the tested conditions; it cannot establish exact ideality at every composition.
Positive or negative deviations of component <partial pressures> require <activity coefficients> different from one under these assumptions. An <azeotrope> is also absent from the chosen unequal-<vapor pressure> model: the explicit inequality in <ideal binary vapor composition> gives $y_A>x_A$ throughout $0<x_A<1$. An interior equality would require $p_A^*=p_B^*$; in that degenerate case every composition has $y_A=x_A$, rather than an isolated enrichment reversal. Neither an <azeotrope> nor <liquid> <phase separation> should be inferred from the ideal curves.
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