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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Solid sodium cyanide salt does not dissociate. However, a solution of NaCN generates HCN, which dissociates with a pKa of 9.36 at 20 °C.

Key value for chemical safety assessment

pKa at 20°C:

Additional information

The pKa of hydrogen cyanide (HCN) determines the species of the CN- anion which is the proximal toxicant in biological/ecological systems. At pH 7-8, all member of the cyanide category (HCN, KCN, NaCN and ACH) form HCN.