Sodium nitrate

Auto flammability

Administrative data

Endpoint:

auto-ignition temperature (liquids)

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Combining three handbook results, sodium nitrate could be described as a colourless hygroscopic crystalline solid, as white granules or as a white powder, deliquesc in moist air.

Physical state at 20°C and 1013 hPa:

solid

-The CRC Handbook of Chemistry and Physics (80th ed.) describes sodium nitrate as colourless hexagonal crystals, hygroscopic.

-The Merck Index (12th ed.) describes sodium nitrate as colourless transparent crystals, white granules or powder, deliquesc in moist air.

-Sax's Dangerous Properties of Industrial Materials (9th. ed.) describes sodium nitrate as colourless, transparent, trigonal (rhombohedral) crystals, deliquesc in moist air.

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Reference

Endpoint:

self-heating substances / mixtures

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Nitrogen is in the highest oxidation state (+5) and will not react exothermic with any atom in the air. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt.

The substance has a wide-spread use and is not known as a self-heating substance.

On heating sodium nitrate melts without decomposition and the liquid is stable in air to at least 500°C. On further heating in air it decomposes into sodium nitrite (NaNO2) and oxygen. Decomposition temperature: 600°C (from publication: High temperature properties and thermal decomposition of inorganic salts with oxyanions, Stern, K.H., CRC Press LLC, Boca Raton, 2001).

Additionally, the Ullman Encyclopedia (see the attachment) contains a chapter on nitrates that describes in particular the uses of potassium and sodium nitrates in high temperature applications, and in particular in solar technology, which implies that they are stable at those temperatures in the long term. Please refer to section 1.5 of the attachment stating the use of potassium/sodium nitrate in high temperature applications.

Nitrates are also used in the production of glass, a process that take place at very high temperatures.