## excess volume (at a solid/liquid interface)

Also contains definition of: excess mass (at a solid/liquid interface)
https://doi.org/10.1351/goldbook.E02237
For a pure liquid, despite its low compressibility, the variation of density near a solid surface can be detected and measured. The total volume $$V$$ of a system consisting of solid and pure liquid is different from (usually less than) that calculated assuming a constant liquid density. If the densities of bulk solid ($$\rho ^{\mathrm{sol}}$$) and liquid ($$\rho ^{\text{l}}$$) are known then an excess volume (usually negative) can be defined as: $V^{\sigma }=V- V^{\mathrm{sol}}- V^{\,\unicode{x26ac}}=V- \frac{m^{\mathrm{sol}}}{\rho ^{\mathrm{sol}}}- \frac{m^{\text{l}}}{\rho ^{\text{l}}}$ where $$m^{\mathrm{sol}}$$ is the mass of solid, $$V^{\mathrm{sol}}$$ its volume calculated from the bulk density, $$V^{\,\unicode{x26ac}}$$ is the initial volume of liquid and $$m^{\text{l}}$$ is the mass of liquid. The excess mass is given by: $m^{\sigma }=m^{\text{l}}- (V- V^{\mathrm{sol}})\ \rho ^{\text{l}}$
Source:
PAC, 1986, 58, 967. (Reporting data on adsorption from solution at the solid/solution interface (Recommendations 1986)) on page 972 [Terms] [Paper]