Redox and Qualitative Analysis (OCR A-Level Chemistry A): Quizzes

Purple solution becomes colourless

$\text{MnO}_4^-$ with $E°$ = +1.33 V

Green

Oxidized back to $\text{Cr}^{3+}$

Same element oxidized and reduced together

Red litmus paper turns blue

Effervescence (fizzing)

Cream

Brown $\text{I}_2$ masks the green colour

To prevent false positives from other ions