Chemistry Class 11 NCERT Solutions: Chapter 8 Redox Reactions Part 3

Chemistry Class 11 NCERT Solutions Chapter 8 Redox Reactions Part 3

Q: 3. Justify that the following reactions are redox reactions:

(A) Equation

(B) Equation

(C) Equation

(D) Equation

(E) Equation

Answer:

(A) Equation

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

Equation

Here, the oxidation number of Cu decreases from +2 in Equation to 0 in Cu i.e., CuO is

reduced to Equation . Also, the oxidation number of H increases from 0 in Equation to +1 in Equation i.e.,

Equation is oxidized to Equation . Hence, this reaction is a redox reaction.

(B) Equation

Equation

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

(C) Equation

The oxidation number of each element in the given reaction can be represented as:

Equation

In this reaction, the oxidation number of B decreases from +3 in Equation to –3 in Equation . i.e.,

Equation is reduced to Equation . Also, the oxidation number of H increases from –1 in Equation to

+1 in Equation i.e., Equation is oxidized to Equation . Hence, the given reaction is a redox reaction.

(D) Equation

The oxidation number of each element in the given reaction can be represented as

Equation

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 Equation to -1 in KF i.e, Equation is reduced to KF.

Hence, the above reaction is a redox reaction.

(E) Equation

The oxidation number of each element in the given reaction can be represented as

Equation

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

Q: 4. Fluorine reacts with ice and results in the change

Equation

Justify that this reaction is a redox reaction.

Answer:

Let us write the oxidation number of each atom involved in the given reaction above its symbol as:

Equation

Here, we have observed that the oxidation number of F increases from 0 in Equation to +1 in Equation . Also, the oxidation number decreases from 0 in Equation to –1 in Equation . Thus, in the above reaction, F is both oxidized and reduced. Hence, the given reaction is a redox reaction.

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