Abstract
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)4 0]. The volume change for the formation of NaB(OH)4 0 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)2 0]. 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).
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1595-1604 |
| Number of pages | 10 |
| Journal | Geochimica et Cosmochimica Acta |
| Volume | 39 |
| Issue number | 12 |
| DOIs | |
| State | Published - 1975 |
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ASJC Scopus subject areas
- Geochemistry and Petrology
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The effect of pressure on the ionization of boric acid in sodium chloride and seawater from molal volume data at 0 and 25°C. / Ward, Gary K.; Millero, Frank J.
In: Geochimica et Cosmochimica Acta, Vol. 39, No. 12, 1975, p. 1595-1604.Research output: Contribution to journal › Article
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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
PY - 1975
Y1 - 1975
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)4 0]. The volume change for the formation of NaB(OH)4 0 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)2 0]. 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)4 0]. The volume change for the formation of NaB(OH)4 0 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)2 0]. 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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UR - http://www.scopus.com/inward/citedby.url?scp=24244452597&partnerID=8YFLogxK
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 -