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The red line on the predominance diagram is not quite horizontal due to the simultaneous equilibrium with the chromate ion. The hydrogen chromate ion may be protonated, with the formation of molecular chromic acid, H 2 CrO 4, but the pK a for the equilibrium H 2 CrO 4 ⇌ HCrO − 4 + H + is not well characterized. Reported values vary between ...
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 .
In chemistry, solvatochromism is the phenomenon observed when the colour of a solution is different when the solute is dissolved in different solvents. [1] [2] Reichardt's dye dissolved in different solvents. The solvatochromic effect is the way the spectrum of a substance (the solute) varies when the substance is dissolved in a variety of ...
The reactivity of the chromate anion with silver is lower than with halides (e.g. chlorides) so that in a mixture of both ions, only silver chloride precipitate will form: [9] AgNO 3(aq) + Cl − (aq) + CrO 2− 4(aq) → AgCl (s) + CrO 2− 4(aq) + NO − 3(aq) Only when no chloride (or any halogen) is left will silver chromate form and ...
The chromate ion is the predominant species in the region to the right of the green and blue lines. Above pH ~6.75 it is always the predominant species. At pH < 5.89 (pH < pK 1) the hydrogen chromate ion is predominant in dilute solution but the dichromate ion is predominant in more concentrated solutions.
Potassium chromate is added as indicator in an Erlenmeyer flask and the end of the reaction is determined by the slight red color given by the silver chromate. In the Mohr method, named after Karl Friedrich Mohr, potassium chromate is an indicator, giving red silver chromate after all chloride ions have reacted: 2Ag + (aq) + CrO 2−
A complexometric indicator is an ionochromic dye that undergoes a definite color change in presence of specific metal ions. [1] It forms a weak complex with the ions present in the solution, which has a significantly different color from the form existing outside the complex. Complexometric indicators are also known as pM indicators.
Strontium chromate is approximately 30 times more soluble in water at 100 °C than at room temperature. Therefore, the yellow strontium chromate can be suspended in a hot solution of a soluble sulfate to digest until fully converted to the much less soluble and white strontium sulfate, leaving the chromate or dichromate in solution.