Sodium azide

Henry's Law constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

Henry's law constant

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline required

GLP compliance:

not specified

H:

>= 12 - <= 12.4 other: M atm-1

Temp.:

25 °C

The Henry's law constant, KH,in dilute aqueous solution was recently determined to be

KH= [HN3]/PHN3= 12.0 M atm-1(25 °C; µ = 0.02 M;DH = -31 ± 1 kJ mol-1) 

Here, µ. =ionic strength.

This is in good agreement with two earlier studies conducted at higher ionic strengths. D'Orazio and Wood [J Phys Chem 1963, 67: 1435-8] reported KH = 12.2-12.4 M atm-1,μ= 0.10-1.65; while Templeton and King [J Am Chem Soc 1971, 93(26): 7160-6] reported KH = 12.1, µ=0.1 -11 M.

Executive summary:

Based on three differend studies, the Henry's law constant was estimated to be 10 - 12.4 M/atm, with ionic strengh values of µ=0.02 - 11M.

Reference 2

Endpoint:

Henry's law constant

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

H:

10.132 Pa m³/mol

Temp.:

30 °C

Volatility of hydrazoic acid from acidified solutions of sodium azide.

Executive summary:

The volatility of hydrazoic acid (the protonated form of the azide anion) in acidified solution was reported to be 76 mm Hg /M, which is equal to 10.132 Pa/m^3/mol.

Description of key information

Betterton (2003) report a Henry's law constant between 10 - 12.4 M/atm. Weiss (1996) state a volatility of hydrazoic acid (the protonated form of the azide anion) in acidified solution of 76 mm Hg /M, which is equal to 10.132 Pa/m^3/mol.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):

10.132

at the temperature of:

20 °C