Volumetric properties of glycine in water at elevated temperatures and pressures measured with a new optically driven vibrating-tube densimeter

A new vibrating-tube densimeter has been constructed for measuring the relative densities of fluid systems in the elevated temperature and pressure ranges 323≤T/K≤533 and 0.1≤p/MPa≤40. The instrument utilizes a light beam in the collection of a signal and dispenses with the usual pick-up and drive wire combinations required in other instruments. The densimeter has been tested by measuring relative densities for aqueous sodium chloride solutions at temperatures fromT=398 K toT=473 K and pressures fromp=10 MPa top=30 MPa. Calculated densities have been compared to those previously published in the literature in order to assess the precision of our new instrument. Also, relative densities for glycine in water have been measured at temperatures fromT=398 K toT=473 K and pressures fromp=10 MPa top=30 MPa over an extended concentration range. Calculated standard state volumes are compared to those which may be calculated from previously published revised Helgeson, Kirkham, and Flowers equations of state.