Silver bromide, or AgBr, is insoluble in water. It forms a yellow precipitate when mixed with water.
In other words, if you mix silver bromide and water, you will notice a pale yellow-colored solid deposit at the bottom of the aqueous solution.
We can check the solubility of silver bromide by checking its value of solubility and solubility product.
Is AgBr Soluble In Water? (Explained)
The solubility and solubility product provides good insight into the solubility of a compound, and they can be utilized to study AgBr as well.
Solubility of AgBr in Water
AgBr has a solubility of 0.140 mg/L at 20℃. The value is very low, further proving that AgBr is a precipitate.
Solubility Product of AgBr
AgBr has a Ksp of 5.4 x 10-2 mol-2 dm-6, which is again low and indicates that AgBr is insoluble in water.
What is Silver Bromide or AgBr?
Silver bromide is an essential light-sensitive compound widely used in photographic processes.
AgBr is the chemical formula for silver bromide and its molar mass is 187.77 grams/mole.
Silver bromide is an inorganic compound consisting of silver metal (Ag) and bromine atoms (Br), held together by a covalent bond, which is ionic in nature.
Solid silver bromide has a face-centered cubic structure similar to that of NaCl.
Physical Properties of Silver Bromide
Silver bromide is an odorless solid with a pale yellow color.
The density of AgBr is 6.47 g/mL, its melting point is 432°C, and its boiling point is 1502°C.
It is not soluble in water.
Chemical Properties of Silver Bromide
The photosensitive property of silver bromide (it absorbs light energy) distinguishes it from other metals.
When exposed to light, silver bromide turns gray or black.
Therefore, it should be stored in the dark.
It readily forms various amine complexes with liquid ammonia.
Under normal conditions, it is stable; however, at high temperatures it decomposes, releasing toxic bromine fumes.
Uses of Silver Bromide
Silver bromide is mainly used for photography because of its light sensitivity.
It is used for making photographic films and plates.
It can also be used to transmit infrared light, for optics with light sensors, and for semiconductors.
Just like the other silver halides, it is also antibacterial and antiseptic and serves as an astringent and topical disinfectant.
Why is Silver Bromide Insoluble in Water?
Solubility refers to the capacity of the solute (solid, liquid, or gas) to dissolve in a solvent (liquid) and form a solution.
The solubility of a substance is largely dependent on the solvent used, temperature, and pressure.
By measuring the concentration of the saturated solution, we can determine how soluble a substance is in a particular solvent.
Silver bromide is insoluble in water and forms a pale yellow precipitate in an aqueous solution.
Despite being an ionic compound, it does not break into its corresponding ions in water.
Also, silver and bromine have low electronegativity differences, as well as a theory referred to as “Fajan’s Rule”.
According to Fajan’s Rule, the ionic radius of silver is similar to that of halides, which allows them to bind close together, making them difficult to dissociate in water.
The solubility of AgBr in water is 0.140 mg/L at 200°C.
The result is a very low value, which indicates that AgBr is a precipitate.
What Happens When Silver Bromide is Exposed to Sunlight?
When silver bromide is exposed to sunlight, a color change is observed because of photochemical decomposition.
When exposed to sunlight, silver bromide is decomposed, resulting in silver and bromide gas being produced.
The decomposition reaction is also referred to as a photochemical reaction in which white AgBr converts into grey-colored silver when exposed to light.
The reaction is as follows:
2AgBr → 2Ag + Br2
Solubility of Different Silver Halides
Here is a comparison of the solubility of different silver halids.
Silver Halide Solubilities:
|Compound||Solubility (g / 100 g H2O)|
The Arrhenius plot of silver bromide’s ionic conductivity shows that it increases and “upward-turns” as it is heated toward its melting point, which is within 100 °C.
Further, the crystal’s elastic modulus, specific heat, and electronic energy gap all increase, indicating it is nearing instability.
Semiconductors exhibit this behavior because of Frenkel defect formation being temperature-dependent, and when normalized against Frenkel defect concentration, the Arrhenius plot linearizes.
Preparation of Silver Bromide
Natural silver bromide is found in the mineral bromargyrite.
Although silver bromide can be found as a mineral, AgBr is usually prepared by reacting silver nitrate with potassium bromide or any other alkali bromide.
The reaction is as follows:
AgNO3 (aq) + KBr (aq) → AgBr (s) + KNO3 (aq)
Alternatively, the salt may also be prepared directly from its elements, even though this is less convenient.
An emulsion of silver halide crystals in gelatine is used to prepare a simple, light-sensitive surface, which is then coated on a film or any other support.
Crystals are then formed in controlled environmental conditions by precipitation to produce small, uniform crystals.
We can conclude that silver bromide is insoluble in water and forms a yellow precipitate in an aqueous solution. All silver halides are insoluble in water, and AgBr is no exception.
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