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Question : 7
Total: 26
When chromite ore FeCr 2 O 4 is fused with NaOH in presence of air, a yellow coloured compound
(A) is obtained which on acidification with dilute sulphuric acid gives a compound (B). Compound
(B) on reaction withKCl forms a orange coloured crystalline compound (C).
(i) Write the formulae of the compounds (A), (B) and (C).
(ii) Write one use of compound (C).
OR
Complete the following chemical equations:
(i)MnO 4 − + 3 S 2 O 3 2 − + H 2 O → ?
(ii)Cr 2 O 7 2 − + 3 Sn 2 + + 14 H + → ?
(A) is obtained which on acidification with dilute sulphuric acid gives a compound (B). Compound
(B) on reaction with
(i) Write the formulae of the compounds (A), (B) and (C).
(ii) Write one use of compound (C).
OR
Complete the following chemical equations:
(i)
(ii)
Solution:
(i) 4 FeCr 2 O 4 + 16 NaOH + 7 O 2 → 8 Na 2 CrO 4 [ A ] + 2 Fe 2 O 3 + 8 H 2 O
Na 2 Cr 2 O 7 [ B ] + 2 KCl → K 2 Cr 2 O 7 [ C ] + 2 NaCl
A : Na 2 CrO 4 B : Na 2 Cr 2 O 7 C : K 2 Cr 2 O 7
(ii) Use ofK 2 Cr 2 O 7 ( C ) : It is used as a strong oxidizing agent in industries.
OR
(i)8 MnO 4 − + 3 S 2 O 3 2 − + H 2 O → 8 MnO 2 + 6 SO 4 2 − + 2 OH −
(ii)Cr 2 O 7 2 − + 3 Sn 2 + + 14 H + → 2 Cr 3 + + 7 H 2 O + 3 Sn 4 +
(ii) Use of
OR
(i)
(ii)
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