Ultrafast acoustics measurements on liquid mercury have been performed at high pressure and temperature in diamond anvils cell using picosecond acoustic interferometry. We extract the density of mercury from adiabatic sound velocities using a numeric
al iterative procedure. The pressure and temperature dependence of the thermal expansion, the isothermal compressibilty, the isothermal bulk modulus and its pressure derivative are derived up to 7 GPa and 520 K. In the high pressure regime, the sound velocity values, at a given density, are shown to be only slightly dependent on the specific temperature and pressure conditions. The density dependence of sound velocity at low density is consistent with that observed with our data at high density in the metallic liquid state.
