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Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information


The test substance is a colourless, odourless hygroscopic crystalline solid at room temperature and pressure.

Melting point

The melting point of potassium bromide is 730 - 734°C at 101.325 kPa

Boiling point

The boiling point of potassium bromide is 1435 °C at 101.325 kPa


The density of potassium bromide is 2.74 g/cm3 at 25°C


Potassium bromide is a hygroscopic inorganic solid. The substance has to maintained at elevated temperatures in a dry environment to maintain the powdered form. Introduction to atmospheric moisture causes clumping and hydration of the substance. It is therefore not technically feasible to perform standard granulometry studies on the substance. Furthermore, the hygroscopic nature of the substance means it is unlikely to form dusts or inhalable aerosols.

Vapour pressure

A vapour pressure study is not required is the melting point of the substance is > 300°C. The melting point of potassium bromide is >= 730°C

Partition coefficient

The substance is a highly water soluble inorganic salt so will partition to the aqueous environment.

Water solubility

The solubility of potassium bromide in water is 687 g/L at 25°C. Potassium bromide is hygroscopic.

Solubility in organic solvents

Potassium bromide is slightly soluble in ethanol, glycerol and alcohol.

Surface tension

Potassium bromide is a simple inorganic salt. It does not contain chemical groups which would be predicted or expected to be surface active, neither is the substance required to be surface active.

Flammability/ flash-point

Potassium bromide is a hygroscopic solid. Upon contact with air the substance begins absorbing water. When used as an analytical reagent in spectroscopy the substance must be maintained in a dry atmosphere at elevated temperatures (100 - 130°C) to reduce the potential from water absorbance. As the substance hydrates in the atmosphere and furthermore will not self-ignite upon contact with air it is not flammable.


Potassium bromide is not flammable and will not evolve highly flammable gases


Potassium bromide is an inorganic salt and does not have any functional groups such as diazo, azide, polynitro or peroxide, which are found in chemically explosive compounds. Therefore, chemical explosion reactions are considered not to occur under ordinary circumstances.

Oxidising properties

Potassium bromide is a stable inorganic salt. The structural formula established beyond reasonable doubt that this substance is incapable of reacting exothermically with combustible material.

Thermal stability

Potassium bromide is stated to be stable up to its melting point of ca. 730 °C

Dissociation constant

KBr is the salt of KOH and HBr. KOH is a strong base. Thus, K+ cation is a weak conjugate acid because it originated from a strong base (KOH). It will not behave as an acid, hence it does not hydrolyse and will solely be a spectator ion in solution. Similarly, Br¯ anion is a weak conjugate base because it originated from a strong acid (HBr). It will not behave as a base; hence it does not hydrolyse and will solely be a spectator ion in solution. Since neither the potassium ion nor the bromide ion is contributing to the hydronium ion or hydroxide ion concentration in solution, the only source for H3O+ or OH¯ in solution is from the dissociation of water. Thus, the concentration of hydronium ion will be 10-7, and the resulting pH of the solution will be 7.