Effect of NaOH addition on the pH of on a lactic acid/sodium lactate buffer.

This example demonstrates:

In the [Reactants Window] there are 4 reactants (Inflows):

       55.508 H2O +  <B> HC3H5O3 +  <B> NaC3H5O3 +  <A> NaOH = 
OLI options in effect: 'Include Redox' - this permits the dissociation reaction NaOH = Na[+](aq) + OH[-](aq).

The amount beta, <B>, of the acid/base couple, must be a constant value (not a range) specified in the [Menu Window]. Unlike <B>, depending up on the type of calculation being performed, the amount alpha, <A> may be set in the [Menu Window] (as in this present example) or calculated in the equilibrium (in which case <A> would be called the target variable).

In the [Menu Window] the gas phase and the aqueous phase have been selected as possible products. <A> is given the range '0 1 0.01' (i.e. 0, 0.01, 0.02 ..0.1 M NaOH). <B> is given the constant value '0.2' (i.e. 0.2 M HC3H5O3 + 0.2 M NaC3H5O3). The product T and P are 25 C and 1 atm.

All data are taken from OLIP (Public.ddb) - the OLI Systems public databank. For this example to work both FactSage and the OLI StreamAnalyzer must be installed on the PC, and the OLIP (Public.ddb) databank must included in the list of databases.

The following show the Equilib results at 0 mol NaOH (<A> = 0) where pH = 3.986, and 0.02 M NaOH (<A> = 0.02) where pH = 4.067. For comparison purposes, the results are also presented for 0.02 M NaOH in the absence of the acid/base buffer (<B> = 0) and give pH = 12.236.


--------------------------------------------------------- FactSage results at 0 mol NaOH (<A> = 0) where pH = 3.986 OLI options in effect: 'Include Redox' --------------------------------------------------------- [FACT Format] 55.508 H2O + <(0.2)> HC3H5O3 + <(0.2)> NaC3H5O3 + <A> NaOH = 0.00000 mol ( 0.31551E-01 H2OVAP + 0.56433E-04 C3H6O3(g)_H2LLACTICACVA + 0.52602E-04 C3H6O3(g2)_LACTICACVAP + 0.30791E-27 H2VAP + 0.90070E-28 O2VAP) ( 25.00 C, 1 atm, gas_OLI, a=0.31660E-01) + 1.0000 mol ( 55.508 H2O + 0.18082 C3H5O3[-1]_HLLACTICACIO + 0.18068 Na[+1]_NAION + 0.99991E-01 C3H6O3_H2LLACTICACAQ + 0.99870E-01 C3H6O3_LACTICACAQ + 0.19316E-01 C3H5NaO3_NALACTATAQ + 0.13919E-03 H[+1]_HION + 0.12747E-09 HO[-1]_OHION + 0.14544E-12 C3H4O3[-2]_LLACTICACION + 0.22504E-30 H2AQ + 0.11252E-30 O2AQ) ( 25.00 C, 1 atm, aqu_OLI) (Eh= 0.377 V, pH= 3.986) where "A" on the reactant side is 0.0000 **************************************************************** H G V S Cp (J) (J) (l) (J/K) (J/K) **************************************************************** -1.61713E+07 -1.73763E+07 1.12358E+00 4.04149E+03 2.31079E+03 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [ChemSage Format] T = 25.00 C P = 1.00000E+00 atm V = 1.12358E+00 dm3 STREAM CONSTITUENTS AMOUNT/mol H2O/aqu_OLI/ 5.5508E+01 C3H6O3(g)_H2LLACTICAC(g) 2.0000E-01 C3H5NaO3_NALACTATAQ/aqu_/ 2.0000E-01 NaOH(s0) 0.0000E+00 EQUIL AMOUNT MOLE FRACTION FUGACITY PHASE: gas_OLI mol atm H2OVAP 0.0000E+00 9.9656E-01 3.0675E-02 C3H6O3(g)_H2LLACTICACVA 0.0000E+00 1.7825E-03 5.2786E-05 C3H6O3(g2)_LACTICACVAP 0.0000E+00 1.6615E-03 5.2722E-05 H2VAP 0.0000E+00 9.7255E-27 2.8802E-28 O2VAP 0.0000E+00 2.8449E-27 8.9539E-29 TOTAL: 0.0000E+00 1.0000E+00 3.1660E-02 PHASE: aqu_OLI mol MOLALITY ACTIVITY H2O 5.5508E+01 5.5508E+01 9.9006E-01 C3H6O3_H2LLACTICACAQ 9.9991E-02 9.9992E-02 1.0173E-01 C3H6O3_LACTICACAQ 9.9870E-02 9.9870E-02 1.0161E-01 H2AQ 2.2504E-31 2.2504E-31 2.2896E-31 O2AQ 1.1252E-31 1.1252E-31 1.1448E-31 C3H5NaO3_NALACTATAQ 1.9316E-02 1.9316E-02 2.0028E-02 HO[-1]_OHION 1.2747E-10 1.2747E-10 9.7382E-11 C3H5O3[-1]_HLLACTICACIO 1.8082E-01 1.8082E-01 1.3407E-01 C3H4O3[-2]_LLACTICACION 1.4544E-13 1.4544E-13 3.8350E-14 Na[+1]_NAION 1.8068E-01 1.8069E-01 1.3397E-01 H[+1]_HION 1.3919E-04 1.3919E-04 1.0321E-04 TOTAL: 5.6089E+01 1.0000E+00 ******************************************************************** Cp_EQUIL H_EQUIL S_EQUIL G_EQUIL V_EQUIL J.K-1 J J.K-1 J dm3 ******************************************************************** 2.31079E+03 -1.61713E+07 4.04149E+03 -1.73763E+07 1.12358E+00 Properties for aqu_OLI: pH = 3.9863 Eh/V = 0.5786 Total solute molality = 0.5808 Ionic strength = 0.1808 Osmotic coefficient = 0.9548 Debye-Hueckel slope = 0.3915 Density/mol.dm-3 = 54.4566 Absolute viscosity/cP = 0.9064 Diffusivities/m2.sec-1: H2O 2.4162E-09 C3H6O3_H2LLACT 1.1943E-10 C3H6O3_LACTICA 1.1943E-10 H2AQ 4.6262E-09 O2AQ 2.1511E-09 C3H5NaO3_NALAC 1.5706E-09 HO[-1]_OHION 5.2492E-09 C3H5O3[-1]_HLL 1.6323E-09 C3H4O3[-2]_LLA 8.2439E-10 Na[+1]_NAION 1.3650E-09 H[+1]_HION 9.2182E-09 Mole fraction of system components: gas_OLI aqu_OLI H 6.6667E-01 6.6547E-01 O 3.3219E-01 3.3095E-01 LLACTICACI 1.1480E-03 2.3849E-03 Na(0) 0.0000E+00 1.1924E-03 System density/g.cm-3 = 0.925988
------------------------------------------------------------- FactSage results at 0.02 M NaOH (<A> = 0.02) where pH = 4.067 OLI options in effect: 'Include Redox' ------------------------------------------------------------- [FACT Format] (Beta version) 55.508 H2O + <(0.2)> HC3H5O3 + <(0.2)> NaC3H5O3 + <A> NaOH = 0.00000 mol ( 0.31543E-01 H2OVAP + 0.50855E-04 C3H6O3(g)_H2LLACTICACVA + 0.47403E-04 C3H6O3(g2)_LACTICACVAP + 0.30786E-27 H2VAP + 0.90055E-28 O2VAP) ( 25.00 C, 1 atm, gas_OLI, a=0.31642E-01) + 1.0004 mol ( 55.508 H2O + 0.19744 C3H5O3[-1]_HLLACTICACIO + 0.19733 Na[+1]_NAION + 0.89964E-01 C3H6O3_H2LLACTICACAQ + 0.89855E-01 C3H6O3_LACTICACAQ + 0.22595E-01 C3H5NaO3_NALACTATAQ + 0.11654E-03 H[+1]_HION + 0.15404E-09 HO[-1]_OHION + 0.19721E-12 C3H4O3[-2]_LLACTICACION + 0.22465E-30 H2AQ + 0.11232E-30 O2AQ) ( 25.00 C, 1 atm, aqu_OLI) (Eh= 0.372 V, pH= 4.067) where "A" on the reactant side is 0.2000E-01 **************************************************************** H G V S Cp (J) (J) (l) (J/K) (J/K) **************************************************************** -1.61819E+07 -1.73872E+07 1.12374E+00 4.04286E+03 2.31078E+03 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [ChemSage Format] T = 25.00 C P = 1.00000E+00 atm V = 1.12374E+00 dm3 STREAM CONSTITUENTS AMOUNT/mol H2O/aqu_OLI/ 5.5508E+01 C3H6O3(g)_H2LLACTICAC(g) 2.0000E-01 C3H5NaO3_NALACTATAQ/aqu_/ 2.0000E-01 NaOH(s0) 2.0000E-02 EQUIL AMOUNT MOLE FRACTION FUGACITY PHASE: gas_OLI mol atm H2OVAP 0.0000E+00 9.9689E-01 3.0667E-02 C3H6O3(g)_H2LLACTICACVA 0.0000E+00 1.6072E-03 4.7569E-05 C3H6O3(g2)_LACTICACVAP 0.0000E+00 1.4981E-03 4.7511E-05 H2VAP 0.0000E+00 9.7296E-27 2.8797E-28 O2VAP 0.0000E+00 2.8461E-27 8.9525E-29 TOTAL: 0.0000E+00 1.0000E+00 3.1642E-02 PHASE: aqu_OLI mol MOLALITY ACTIVITY H2O 5.5528E+01 5.5508E+01 9.8981E-01 C3H6O3_H2LLACTICACAQ 8.9996E-02 8.9964E-02 9.1676E-02 C3H6O3_LACTICACAQ 8.9887E-02 8.9855E-02 9.1564E-02 H2AQ 2.2473E-31 2.2465E-31 2.2892E-31 O2AQ 1.1236E-31 1.1232E-31 1.1446E-31 C3H5NaO3_NALACTATAQ 2.2603E-02 2.2595E-02 2.3541E-02 HO[-1]_OHION 1.5409E-10 1.5404E-10 1.1712E-10 C3H5O3[-1]_HLLACTICACIO 1.9751E-01 1.9744E-01 1.4535E-01 C3H4O3[-2]_LLACTICACION 1.9728E-13 1.9721E-13 5.0013E-14 Na[+1]_NAION 1.9740E-01 1.9733E-01 1.4526E-01 H[+1]_HION 1.1658E-04 1.1654E-04 8.5792E-05 TOTAL: 5.6126E+01 1.0000E+00 ******************************************************************** Cp_EQUIL H_EQUIL S_EQUIL G_EQUIL V_EQUIL J.K-1 J J.K-1 J dm3 ******************************************************************** 2.31078E+03 -1.61819E+07 4.04286E+03 -1.73872E+07 1.12374E+00 Properties for aqu_OLI: pH = 4.0666 Eh/V = 0.5739 Total solute molality = 0.5973 Ionic strength = 0.1974 Osmotic coefficient = 0.9516 Debye-Hueckel slope = 0.3915 Density/mol.dm-3 = 54.4906 Absolute viscosity/cP = 0.9078 Diffusivities/m2.sec-1: H2O 2.4115E-09 C3H6O3_H2LLACT 1.1919E-10 C3H6O3_LACTICA 1.1919E-10 H2AQ 4.6176E-09 O2AQ 2.1470E-09 C3H5NaO3_NALAC 1.5675E-09 HO[-1]_OHION 5.2091E-09 C3H5O3[-1]_HLL 1.6243E-09 C3H4O3[-2]_LLA 8.2130E-10 Na[+1]_NAION 1.3590E-09 H[+1]_HION 9.1351E-09 Mole fraction of system components: gas_OLI aqu_OLI H 6.6667E-01 6.6536E-01 O 3.3230E-01 3.3095E-01 LLACTICACI 1.0351E-03 2.3840E-03 Na(0) 0.0000E+00 1.3112E-03 System density/g.cm-3 = 0.926573
---------------------------------------------------------------------- FactSage results at 0.02 M NaOH in the absence of the acid/base buffer - pH = 12.236 OLI options in effect: 'Include Redox' ---------------------------------------------------------------------- [FACT Format] 55.508 H2O + <(0)> HC3H5O3 + <(0)> NaC3H5O3 + <A> NaOH = 0.00000 mol ( 0.31846E-01 H2OVAP + 0.30982E-27 H2VAP + 0.90631E-28 O2VAP) ( 25.00 C, 1 atm, gas_OLI, a=0.31846E-01) + 1.0000 mol ( 55.508 H2O + 0.20000E-01 HO[-1]_OHION + 0.20000E-01 Na[+1]_NAION + 0.67156E-12 H[+1]_HION + 0.22908E-30 H2AQ + 0.11454E-30 O2AQ) ( 25.00 C, 1 atm, aqu_OLI) (Eh=-0.111 V, pH=12.236) where "A" on the reactant side is 0.2000E-01 **************************************************************** H G V S Cp (J) (J) (l) (J/K) (J/K) **************************************************************** -1.58582E+07 -1.70355E+07 1.12141E+00 3.94874E+03 2.26912E+03 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [ChemSage Format] T = 25.00 C P = 1.00000E+00 atm V = 1.12141E+00 dm3 STREAM CONSTITUENTS AMOUNT/mol H2O/aqu_OLI/ 5.5508E+01 C3H6O3(g)_H2LLACTICAC(g) 0.0000E+00 C3H5NaO3_NALACTATAQ/aqu_/ 0.0000E+00 NaOH(s0) 2.0000E-02 EQUIL AMOUNT MOLE FRACTION FUGACITY PHASE: gas_OLI mol atm H2OVAP 0.0000E+00 1.0000E+00 3.0961E-02 H2VAP 0.0000E+00 9.7287E-27 2.8981E-28 O2VAP 0.0000E+00 2.8459E-27 9.0096E-29 TOTAL: 0.0000E+00 1.0000E+00 3.1846E-02 PHASE: aqu_OLI mol MOLALITY ACTIVITY H2O 5.5508E+01 5.5508E+01 9.9931E-01 H2AQ 2.2908E-31 2.2908E-31 2.3038E-31 O2AQ 1.1454E-31 1.1454E-31 1.1519E-31 HO[-1]_OHION 2.0000E-02 2.0000E-02 1.7477E-02 Na[+1]_NAION 2.0000E-02 2.0000E-02 1.7477E-02 H[+1]_HION 6.7156E-13 6.7157E-13 5.8042E-13 TOTAL: 5.5548E+01 1.0000E+00 ******************************************************************** Cp_EQUIL H_EQUIL S_EQUIL G_EQUIL V_EQUIL J.K-1 J J.K-1 J dm3 ******************************************************************** 2.26912E+03 -1.58582E+07 3.94874E+03 -1.70355E+07 1.12141E+00 Properties for aqu_OLI: pH = 12.2363 Eh/V = 0.0905 Total solute molality = 0.0400 Ionic strength = 0.0200 Osmotic coefficient = 0.9600 Debye-Hueckel slope = 0.3915 Density/mol.dm-3 = 55.3786 Absolute viscosity/cP = 0.8948 Diffusivities/m2.sec-1: H2O 2.2737E-09 C3H6O3_H2LLACT 1.1270E-10 C3H6O3_LACTICA 1.1270E-10 H2AQ 4.3535E-09 O2AQ 2.0275E-09 C3H5NaO3_NALAC 1.4831E-09 HO[-1]_OHION 4.9957E-09 C3H5O3[-1]_HLL 1.5486E-09 C3H4O3[-2]_LLA 7.8024E-10 Na[+1]_NAION 1.2973E-09 H[+1]_HION 8.7806E-09 Mole fraction of system components: gas_OLI aqu_OLI H 6.6667E-01 6.6655E-01 O 3.3333E-01 3.3333E-01 Na(0) 0.0000E+00 1.2006E-04 System density/g.cm-3 = 0.892441