The temperature dependence of internal pressure in liquids

Internal pressures were calculated for a large variety of liquids in a wide temperature range from abundant experimental data on isothermal compressibility and thermal volumetric expansion coefficients obtained on a unique piesometric unit. The temperature coefficient of internal pressure was shown to be a structural characteristic of liquids. This coefficient was found to be positive for weakly associated liquids whose structure approximated close packing and negative for liquids with a spatial network of H-bonds. The largest negative temperature coefficient of internal pressure was obtained for water, whose spatial network of H-bonds was most perfect.