text: To calculate this composition, account must be taken of the above equilibria between the three different carbonate forms (H2CO3, HCO3− and CO32−) as well as of the hydration equilibrium between dissolved CO2 and H2CO3 with constant '"`UNIQ--postMath-00001AFD-QINU`"' (see above) and of the following equilibrium between the dissolved CO2 and the gaseous CO2 above the solution: