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Justify that the following reactions are redox reactions: (a) CuO(s...

Justify that the following reactions are | Class 11 Chemistry Chapter Redox Reactions, Redox Reactions NCERT Solutions

Question:

Justify that the following reactions are redox reactions:

(a) CuO_(s) + H_2(g) → Cu_(s)+ H₂O_(g)

(b) Fe₂O_3(s) + 3CO_(g)→ 2Fe_(s) + 3CO_2(g)

(c) 4BCl_3(g) + 3LiAlH_4(s) → 2B₂H_6(g)+ 3LiCl_(s)+ 3 AlCl_{3 (s)}

(d) 2K_(s)+ F_2(g) → 2K⁺F^–_(s)

(e) 4 NH_3(g) + 5 O_2(g)→ 4NO_(g)+ 6H₂O_(g)

Answer:

(a) CuO_(s) + H_2(g) → Cu_(s)+ H₂O_(g)

Let us write the oxidation number of each element involved in the given reaction as:

+2 -2 0 0 +1 -2

Cu O_(s) + H_2(g) → Cu_(s)+ H₂ O_(g)

Here, the oxidation number of Cu decreases from +2 in CuO to 0 in Cu i.e., CuO is reduced to Cu. Also, the oxidation number of H increases from 0 in H₂ to +1 in H₂O i.e., H₂ is oxidized to H₂O. Hence, this reaction is a redox reaction.

(b) Fe₂O_3(s) + 3CO_(g)→ 2Fe_(s) + 3CO_2(g)

Let us write the oxidation number of each element involved in the given reaction as:

+3 -2 +2 -2 0 +4 -2

Fe₂ O_3(s) + 3C O_(g)→ 2Fe_(s) + 3C O_2(g)

Here, the oxidation number of Fe decreases from +3 in Fe₂O₃ to 0 in Fe i.e., Fe₂O₃ is reduced to Fe. On the other hand, the oxidation number of C increases from +2 in CO to +4 in CO₂ i.e., CO is oxidized to CO₂. Hence, the given reaction is a redox reaction.

(c) 4BCl_3(g) + 3LiAlH_4(s) → 2B₂H_6(g)+ 3LiCl_(s)+ 3 AlCl_{3 (s)}

Let us write the oxidation number of each element involved in the given reaction as:

+3 -1 +1 +3 -1 -3 +1 +1 -1 +3 -1

4B Cl_3(g) + 3 Li Al H_4(s) → 2B₂H_6(g)+ 3Li Cl_(s)+ 3 Al Cl_{3 (s)}

In this reaction, the oxidation number of B decreases from +3 in BCl₃ to –3 in B₂H₆. i.e., BCl₃ is reduced to B₂H₆. Also, the oxidation number of H increases from –1 in LiAlH₄ to +1 in B₂H₆ i.e., LiAlH₄ is oxidized to B₂H₆. Hence, the given reaction is a redox reaction.

(d) 2K_(s)+ F_2(g) → 2K⁺F^–_(s)

Let us write the oxidation number of each element involved in the given reaction as:

0 0 +1 -1

2K_(s)+ F_2(g) → 2K⁺F^–_(s)

In this reaction, the oxidation number of K increases from 0 in K to +1 in KF i.e., K is oxidized to KF. On the other hand, the oxidation number of F decreases from 0 in F₂ to – 1 in KF i.e., F₂ is reduced to KF.

Hence, the above reaction is a redox reaction.

(e) 4 NH_3(g) + 5 O_2(g)→ 4NO_(g)+ 6H₂O_(g)

Let us write the oxidation number of each element involved in the given reaction as:

-3 +1 0 +2 -2 +1 -2

4 N H_3(g) + 5 O_2(g)→ 4N O_(g)+ 6H₂O_(g)

Here, the oxidation number of N increases from –3 in NH₃ to +2 in NO. On the other hand, the oxidation number of O₂ decreases from 0 in O₂ to –2 in NO and H₂O i.e., O₂ is reduced. Hence, the given reaction is a redox reaction.

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Comments

SwapnilAgrawal
2019-08-29 21:39:26

Thanks ...it's better way to check nd get the answers of NCERT

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Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 3: Justify that the following reactions are redox reactions: (a) CuO(s) + H2(g) → Cu(s) + H2O(g....