Ternary isothermal diffusion coefficients of NaCl-MgCl2-H2O at 25°C.: 7.: Seawater composition

The four diffusion coefficients D (ij) of the ternary system NaCl-MgCl2-H2O at the simplified seawater composition 0.48877 mol center dot dm(-3) NaCl and 0.05110 mol center dot dm(-3) MgCl2 have been remeasured at 25 degrees C. The diffusion coefficients were obtained using both Gouy and Rayleigh interferometry with the highly precise Gosting diffusiometer. The results, which should be identical in principle, are essentially the same within or very close to their combined "realistic" errors. This system has a cross-term D (12) that is larger than the D (22) main-term, where subscript 1 denotes NaCl and 2 denotes MgCl2. The results are compared with earlier, less-precise measurements. Recommended values for this system are (D (11)) (V) =1.432x10(-9) m(2)center dot s(-1), (D-12) (V) =0.750x10(-9) m(2)center dot s(-1), (D (21)) (V) =0.0185x10(-9) m(2)center dot s(-1), and (D-22) (V) =0.728x10(-9) m(2)center dot s(-1).