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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Dissociation constant

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Administrative data

Link to relevant study record(s)

Description of key information

Sodium carbonate is very soluble in water.
It dissociates readily into sodium ions (Na+) and carbonate (CO3 2-) ions which form bicarbonate (HCO3-) ions with the water.
The pKa of CO3 2- is 10.33, which means that at a pH of 10.33 both carbonate and bicarbonate are present in equal amounts

Key value for chemical safety assessment

pKa at 20°C:

Additional information

In water, sodium carbonate dissociates into sodium and carbonate An emission of sodium carbonate to water will result in an increase in alkalinity and a tendency to raise the pH value. The carbonate ions will react with water, resulting in the formation of bicarbonate and hydroxide, until an equilibrium is established