KVPY2018Chemistryp Block Elements (Group 15, 16, 17 & 18)
The heating of NH 4 2 Cr 2 O 7 produces another chromium compound along with N 2 gas. The change of the oxidation state of Cr in the reaction is
Options
- A+ 6 to + 2
- B+ 7 to + 4
- C+ 8 to + 4
- D+ 6 to + 3
Correct answer
D. + 6 to + 3
Step-by-step solution
The heating of NH 4 2 Cr 2 O 7 produces Cr 2 O 3 compound along with N 2 . NH 4 2 Cr 2 O 7 ⟶ Δ N 2 + Cr 2 O 3 + 4 H 2 O Let the oxidation state of Cr be x In NH 4 2 Cr 2 O 7 = 2 + 1 + 2 x + 7 - 2 = 0 2 + 2 x - 14 = 0 x = + 6 In Cr 2 O 3 2 x + 3 - 2 = = 2 x - 6 = 0 x = + 3 ∴ The change of the oxidation state of Cr in the reaction is from + 6 to + 3