NCERT Solutions for Class 11-science Chemistry Chapter 8 - Redox Reactions

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Chapter 8 - Redox Reactions Exercise 280

Solution 1

a. NaH2PO4

Let the oxidation number of P be x.

We know that,

Oxidation number of Na = +1

Oxidation number of H = +1

Oxidation number of O = –2

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Then, we have

1(+1) +2(+1)+1(x)+4(-2) =0

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions1+2+x-8 = 0

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactionsx = +5

Hence, the oxidation number of P is +5.

 

b. NaHSO4

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of S is + 6.

 

c. H4P2O7

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of P is + 5.

 

d. K2MnO4

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of Mn is + 6.


e. CaO2

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of O is – 1.

 

f. NaBH4

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of B is + 3.


g. H2S2O7

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of S is + 6.

 

h. KAl(SO4)2.12H2O

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Or,

We can ignore the water molecule as it is a neutral molecule. Then, the sum of the oxidation numbers of all atoms of the water molecule may be taken as zero. Therefore, after ignoring the water molecule, we have

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Hence, the oxidation number of S is + 6.


Solution 2

a. KI3

In KI3, the oxidation number (O.N.) of K is +1. Hence, the average oxidation number of I is Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions. However, O.N. cannot be fractional. Therefore, we will have to consider the structure of KI3 to find the oxidation states.
In a KI3 molecule, an atom of iodine forms a coordinate covalent bond with an iodine molecule.
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Hence, in a KI3 molecule, the O.N. of the two I atoms forming the I2 molecule is 0, whereas the O.N. of the I atom forming the coordinate bond is –1.


 b. H2S4O6

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

However, O.N. cannot be fractional. Hence, S must be present in different oxidation states in the molecule.

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

 The O.N. of two of the four S atoms is +5 and the O.N. of the other two S atoms is 0.


 c. Fe3O4

On taking the O.N. of O as –2, the O.N. of Fe is found to be Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions. However, O.N. cannot be fractional.

Here, one of the three Fe atoms exhibits the O.N. of +2 and the other two Fe atoms exhibit the O.N. of +3.

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

  d. CH3CH2OH

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

 Hence, the O.N. of C is –2.


   e. CH3COOH

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

However, 0 is average O.N. of C. The two carbon atoms present in this molecule are present in different environments. Hence, they cannot have the same oxidation number. Thus, C exhibits the oxidation states of +2 and –2 in CH3COOH.

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 3


Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 4

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 5



Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 6

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 7

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 8

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 9

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Chapter 8 - Redox Reactions Exercise 281

Solution 10

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox ReactionsNcert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 11


Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 12

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 13


Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 14

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 15

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 16

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 17

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Chapter 8 - Redox Reactions Exercise 282

Solution 18

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 19

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 20

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 21

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 22

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 23

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions
Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 24

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 25

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 26

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Chapter 8 - Redox Reactions Exercise 283

Solution 27

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 28

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 29

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions

Solution 30

Ncert Solutions Cbse Class 11-science Chemistry Chapter - Redox Reactions