.Chemical.Examples.AcidBase.CarbonDioxideInWater

Information

CO2 solution in water without any other acid-base buffers.

plotExpression(apply(-log10(CarbonDioxideInWater.H3O.solute)), false, "pH", 1);

Please note, that OH- (and CO3^-2) can be neglected from electroneutrality calculation, because of very small concentrations (in physiological pH) anyway.

And if SID>0 then also H3O+ can be also neglected from electroneutrality, because only bicarbonate anions HCO3- (or CO3^-2) are needed there to balance the electroneutrality.

The partial pressure of CO2 in gas are input parameter. Outputs are an amount of free dissolved CO2 in liquid and an amount of HCO3-.

The titration slope der(pH)/der(SID)=17.5 1/(mol/L) at pH=7.4 and pCO2=40 mmHg.

Molar heat of formation (aqueous):

CO2: -413.5 kJ/mol (gas: -393.5 kJ/mol )

H2O: -285.8 kJ/mol

HCO3-: -692.0 kJ/mol

CO3^-2: -677.1 kJ/mol

Enthalphy of reaction H2O + CO2 <-> HCO3- + H+ : 7.3 kJ/mol

Enthalphy of reaction HCO3- <-> CO3^-2 + H+ : 14.9 kJ/mol

Revisions

2014-2018

Marek Matejak, Charles University, Prague, Czech Republic