Analytical ChemistryHard
Question
Na2SO4 and Na2S can be distinguished from each other by using :
Options
A.dilute H2SO4
B.acidified KMnO4 solution
C.sodium nitroprusside solution
D.cadmium acetate solution
Solution
(A) Na2S + H+ → H2S ↑ + 2Na+. ; Na2SO4 gives no reaction with H2SO4.
(B) 2MnO4- (pink solution) + 5H2S + 6H+ → 2Mn2+ (colourless) + 5S ↓ + 8H2O.
No colour change is observed with Na2SO4.
(C) S2- + [Fe(CN)5NO]2- → [Fe(CN)5NOS]4- (purple or violet colouration).
No colour change is observed with Na2SO4.
(D) S2- + Cd2+ → CdS↓ (yellow).
Na2SO4 forms CdSO4 which is water soluble.
(B) 2MnO4- (pink solution) + 5H2S + 6H+ → 2Mn2+ (colourless) + 5S ↓ + 8H2O.
No colour change is observed with Na2SO4.
(C) S2- + [Fe(CN)5NO]2- → [Fe(CN)5NOS]4- (purple or violet colouration).
No colour change is observed with Na2SO4.
(D) S2- + Cd2+ → CdS↓ (yellow).
Na2SO4 forms CdSO4 which is water soluble.
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