LG as you were x
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What is the test-tube qualitative analysis for Cr3+
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Wolfram Alpha
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I'm assumming you're talking about alcohols and the use of potassium dichromate (VI). If you add [K2Cr2O7]2- in excess with dilute H2SO4 to a primary alcohol and heat under reflux, it will oxidise the alcohol to a carboxylic acid. This results in the reduction of the orange [Cr2O7]2- ion to the green Cr3+ ion. The same colour change is observed when a secondary alcohol is oxidised to a ketone via distillation. If potassium dichromate (VI) is not in excess and distillation is used, then the primary alcohol will be oxidised to an aldehyde and not a carboylic acid.
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LG as you were x
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Nah it’s the very last part of module transition elements
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Kian Stevens
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(Original post by LG as you were x)
Nah it’s the very last part of module transition elements
Add aqueous sodium hydroxide. This is the qualitative test for any transition metal ion, as they will undergo precipitation reactions to form coloured precipitates.

In the OCR specification, there will be a colour change from a violet solution (the Cr3+ ion) to a grey/green precipitate (Cr(OH)3).
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