Speed of sound in NaCl, MgCl₂, Na₂SO₄, and MgSO₄aqueous solutions as functions of concentration, temperature, and pressure

The speeds of sound in aqueous solutions of NaCL, MgCl₂, Na₂SO₄, and MgSO₄have been measured relative to pure water from 0 to 1 molal ionic strength, 0° to 55° C, and 0 to 1000 bar applied pressure. The 1-atm results have been fitted to polynomial equations of concentration and temperature with standard deviations of about 0.1 m/s, U⁰— U_W⁰= am+bm^3/2+cm²where U₀and U_W⁰are the 1-atm sound speeds in solution and in pure water, respectively; mis molality; and a, b, and c are temperature-dependent parameters. The effect of pressure on the relative speeds of sound has been fitted to equations of the form (U^p— U^P_W)—(U⁰— U_W⁰) =dm +em ^3/2+fm ², where U^pandU^P_Ware the sound speeds of the solution and water at applied pressure P and d, e, and f are temperature and pressure-dependent parameters. The standard deviations of the least-squares fits are within 0.12 m/s for all the salts.