Search results
Results from the WOW.Com Content Network
[notes 1] The chromate ion is the predominant species in alkaline solutions, but dichromate can become the predominant ion in acidic solutions. Further condensation reactions can occur in strongly acidic solution with the formation of trichromates, Cr 3 O 2− 10, and tetrachromates, Cr 4 O 2− 13. [2]
Prior to the endpoint the solution has a milky lemon-yellow appearance, due to the suspension of the AgCl precipitate already formed and the yellow colour of the chromate ion in solution. Approaching the endpoint, additions of AgNO 3 lead to steadily more slowly disappearing red colouration.
The solution needs to be near neutral, because silver hydroxide forms at high pH, while the chromate forms Ag 2 Cr 2 O 7 or AgHCrO4 at low pH, reducing the concentration of chromate ions, and delaying the formation of the precipitate. Carbonates and phosphates precipitate with silver, and need to be absent to prevent inaccurate results.
Potassium dichromate, K 2 Cr 2 O 7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health.
Potassium chromate is the inorganic compound with the formula K 2 CrO 4. ... although the chromate ion adopts the typical tetrahedral geometry. [2] ... In solution ...
Chromate and dichromate, ions; Monochromate, an ion; Trichromate, an ion; ... Monochromacy (monochromate) having one color vision; Dichromatism (dichromate) having ...
The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy .
When the pH of the solution is increased by adding an alkaline solution to it, the extent of hydrolysis increases. Measurements of pH or colour change are used to derive the equilibrium constant for the reaction. Further hydrolysis may occur, producing dimeric, trimeric or polymeric species containing hydroxy- or oxy- groups.