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The d-And-f-Block Elements
Question
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What happens when chromates are kept in acidic solution and dichromate in alkaline solution?

Answer

When a chromium (III) salt is heated in alkaline solution with a peroxide a chromate (VI) ion is formed.

2Cr3+(aq) +4OH-(aq)+3O22-(aq) ---> 2CrO42- (aq)+2H2O(l) 

The Cr3+ (aq) ion is blue -violet the CrO42- (aq) ion yellow.

In acid solution yellow chrmoateVI ions Condense to form orange dichromate(VI) ion.

2CrO42- (aq) +2H+ (aq) ---> Cr2O72-(aq) +2H2O(l)

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Some More Questions From The d-And-f-Block Elements Chapter

Silver atom has a completely filled d orbitals (4d10) in its ground state. How can you say that it is a transition element?

In the series Sc (Z = 21) to Zn(Z = 30), the enthalpy of atomisation of zinc is the lowest i.e., 26, kJ mol. Why?

The E° (M2+/M) value for copper is positive (+ 0.34 V). What is possibility the reason for this? 

How would you account for the irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?

Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

Which is a stronger reducing agent Cr2+ or Fe2+ and why?

Explain why Cu+ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?