Silver chromate


Silver chromate
Identifiers
CAS number 7784-01-2
Properties
Molecular formula Ag2CrO4
Molar mass 331.73 g/mol
Appearance brown-red powder
Density 5.625 g/cm3
Solubility in water 1.1x10-12 mol cm-3
Solubility soluble in nitric acid, ammonia, alkali cyanides and chromates [1]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Silver chromate (Ag2CrO4) is a brown-red monoclinic crystal and is a chemical precursor to modern photography. It can be formed by combining silver nitrate (AgNO3) and potassium chromate (K2CrO4). This reaction has been important in neuroscience, as it is used in the "Golgi method" of staining neurons for microscopy: the silver chromate produced precipitates inside neurons and makes their morphology visible.

Laboratory use

The use of the compound itself in the laboratory is rather limited, although its formation is used to indicate the endpoint in the titration of chloride with silver nitrate in the Mohr method of argentometry.

The solubility of silver chromate is slightly higher than that of silver chloride. So, in a mixture of both ions silver chloride will be formed. Only when no chloride is left, will silver chromate show its color.

Prior to the endpoint the solution has a milky lemon yellow appearance, due to the color of the chromate ion and the precipitate of silver chloride already formed. When approaching the endpoint, additions of silver nitrate lead to steadily slower disappearing red colorations. When the red brownish color remains (with grayish spots of silver chloride in it) the endpoint of titration is reached.

References

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398


Stub icon This inorganic compound-related article is a stub. You can help Wikipedia by expanding it.
nuvola





stock | retire | vm
Why are we here?
All text is available under the terms of the GNU Free Documentation License
This page is cache of Wikipedia. History