TY - JOUR
T1 - The effect of pressure on the ionization of boric acid in sodium chloride and seawater from molal volume data at 0 and 25°C
AU - Ward, Gary K.
AU - Millero, Frank J.
N1 - Funding Information:
Acknowledgement-The authorsw ould like to acknowledge the supporto f the Office of Naval Research( N00014-67-A-02Oi-~13)a nd the OceanographicS ectiono f the National f:ciyx Foundation (GA-17386a nd GA-40532).f or this FISHERF ., YEAGERE ., BRES~ERL . and MICELI J. (1972) Origin of the relazationasl ound absorptioni n seawater below 1 kHz. Abstracts of 84th Meeting of Acoustical Sot. Amer. Nov. 28. 1972D. D.9 2-93. HA.MAE~SN. D . (1957~) h~s~c~~~emicai pacts of Pressure, 376 pp. Butterworths. HAMANNS . D. (1972)V olume changesf or the ionization of weake lectrolyteas nd the effectso f pressureo n ioniza-tion, a critical compilation. Dw. Appl. Chem. Tech. Paper (3) CSIRO, Australia. HANSXIN1 .( 1972A) n analyticaal pproacht o the carbonate systemi n seawaterP. h.D. Thesis, University of GBte-berg, Giiteborg, Sweden. HARNEDH . S. and OWEN B. B. (1958)T he Phvsical Che-mistry of Electro/.vte Solutions8, 03p p. Reinhold. HAWLEYJ . E. and PYTKOWICZR . M. (1973)In terpretation of pH measurementisn concentratede lectrolytes olu-tions. Mar. Chem. 1, 245-250. KELL G. S. (1967P) reciser epre~ntationo f volumep roper-ties of water at one atmosphereJ.. Chem. Eng. Data 12. 66-69.
PY - 1975/12
Y1 - 1975/12
N2 - The apparent molal volume, φV of boric acid, B(OH)3 and sodium borate, NaB(OH)4, have been determined in 35%. salinity seawater and 0·725 molal NaCl solutions at 0 and 25°C from precise density measurements. Similar to the behavior of nonelectrolytes and electrolytes in pure water, the φV of B(OH)3 is a linear function of added molality and the φV of NaB(OH)4 is a linear function of the square root of added molarity in seawater and NaCl solutions. The partial molal volumes, V ̄*, of B(OH)3 and NaB(OH)4 in seawater and NaCl were determined from the φV's by extrapolating to infinite dilution in the medium. The V ̄* of B(OH)3 is larger in NaCl and seawater than pure water apparently due to the ability of electrolytes to dehydrate the nonelectrolyte B(OH)3. The V ̄* of NaB(OH)4 in itself, NaCl and seawater is larger than the expected value at 0·725 molal ionic strength due to ion pair formation [Na+ + B(OH)4- → NaB(OH)40]. The volume change for the formation of NaB(OH)40 in itself and NaCl was found to be equal to 29·4 ml mol-1 at 25°C and 0·725 molal ionic strength. These large Δ V ̄*'s indicate that at least one water molecule is released when the ion pair is formed [Na+ + B(OH)4- → H2O + NaOB(OH)20]. The observed V ̄* in seawater and the Δ V ̄* (NaB0) in water and NaCl were used to estimate Δ V ̄* (MgB+) = Δ V ̄* (CaB+) = 38·4 ml mol-1 for the formation of MgB+ and CaB+. The volume change for the ionization of B(OH)3 in NaCl and seawater was determined from the molal volume data. Values of Δ V ̄* = -29·2 and -25·9 ml mol-1 were found in seawater and Δ V ̄* = -21·6 and -26·4 in NaCl, respectively, at 0 and 25°C. The effect of pressure on the ionization of B(OH)3 in NaCl and seawater at 0 and 25°C determined from the volume change is in excellent agreement with direct measurements in artificial seawater (culberson and Pytkowicz, 1968; Disteche and Disteche, 1967) and natural seawater (Culberson and Pytkowicz, 1968).
AB - The apparent molal volume, φV of boric acid, B(OH)3 and sodium borate, NaB(OH)4, have been determined in 35%. salinity seawater and 0·725 molal NaCl solutions at 0 and 25°C from precise density measurements. Similar to the behavior of nonelectrolytes and electrolytes in pure water, the φV of B(OH)3 is a linear function of added molality and the φV of NaB(OH)4 is a linear function of the square root of added molarity in seawater and NaCl solutions. The partial molal volumes, V ̄*, of B(OH)3 and NaB(OH)4 in seawater and NaCl were determined from the φV's by extrapolating to infinite dilution in the medium. The V ̄* of B(OH)3 is larger in NaCl and seawater than pure water apparently due to the ability of electrolytes to dehydrate the nonelectrolyte B(OH)3. The V ̄* of NaB(OH)4 in itself, NaCl and seawater is larger than the expected value at 0·725 molal ionic strength due to ion pair formation [Na+ + B(OH)4- → NaB(OH)40]. The volume change for the formation of NaB(OH)40 in itself and NaCl was found to be equal to 29·4 ml mol-1 at 25°C and 0·725 molal ionic strength. These large Δ V ̄*'s indicate that at least one water molecule is released when the ion pair is formed [Na+ + B(OH)4- → H2O + NaOB(OH)20]. The observed V ̄* in seawater and the Δ V ̄* (NaB0) in water and NaCl were used to estimate Δ V ̄* (MgB+) = Δ V ̄* (CaB+) = 38·4 ml mol-1 for the formation of MgB+ and CaB+. The volume change for the ionization of B(OH)3 in NaCl and seawater was determined from the molal volume data. Values of Δ V ̄* = -29·2 and -25·9 ml mol-1 were found in seawater and Δ V ̄* = -21·6 and -26·4 in NaCl, respectively, at 0 and 25°C. The effect of pressure on the ionization of B(OH)3 in NaCl and seawater at 0 and 25°C determined from the volume change is in excellent agreement with direct measurements in artificial seawater (culberson and Pytkowicz, 1968; Disteche and Disteche, 1967) and natural seawater (Culberson and Pytkowicz, 1968).
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U2 - 10.1016/0016-7037(75)90082-4
DO - 10.1016/0016-7037(75)90082-4
M3 - Article
AN - SCOPUS:24244452597
VL - 39
SP - 1595
EP - 1604
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
IS - 12
ER -