Qstnid -Ii-17- For M2+/m And M3+/m2+ systems, The <Img Src="\etl\image\esa-cbse-xii\chem-hwh-sb1\c08/2_m2a4ae6ba.jpg" Width="18" Height="23" Border="0"> Values For Some Metals Are As Follows: Cr2+/cr -0.9v Cr3/cr2+ -0.4 V Mn2+/mn -1.2v Mn3+ /Mn2+ +1.5 V Fe2+ /Fe -0.4v Fe3+/fe2+ +0.8 V Use This Data To Comment Upon: () The Stability Of Fe3+ In Acid Solution As Compared To That Of Cr3+ Or Mn3+ and () The Ease With Which Iron Can Be Oxidised As Compared To A Similar Process For Either Chromium Or Manganese Metal. () The Stability Of Fe3+ In Acid Solution As Compared To That Of Cr3+ Or Mn3+ and () The Ease With Which Iron Can Be Oxidised As Compared To A Similar Process For Either Chromium Or Manganese Metal. - 08: The D-and F-block Elements

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NEET-XII-Chemistry

08: The d-and f-Block Elements

page 3

Qstn# II-17 Prvs-Qstn Next-Qstn

#17
For M²⁺/M and M³⁺/M²⁺systems, the values for some metals are as follows:

Cr²⁺/Cr -0.9V

Cr³/Cr²⁺ -0.4 V

Mn²⁺/Mn -1.2V

Mn³⁺ /Mn²⁺ +1.5 V

Fe²⁺ /Fe -0.4V

Fe³⁺/Fe²⁺ +0.8 V

Use this data to comment upon:
() The stability of Fe³⁺ in acid solution as compared to that of Cr³⁺ or Mn³⁺and
() The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
() The stability of Fe³⁺ in acid solution as compared to that of Cr³⁺ or Mn³⁺and
() The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
Ans : null () The value for Fe³⁺/Fe²⁺ is higher than that for Cr³⁺/Cr²⁺ and lower than that for Mn³⁺/Mn²⁺. So, the reduction of Fe³⁺ to Fe²⁺ is easier than the reduction of Mn³⁺ to Mn²⁺, but not as easy as the reduction of Cr³⁺to Cr²⁺. Hence, Fe³⁺ is more stable than Mn³⁺, but less stable than Cr³⁺. These metal ions can be arranged in the increasing order of their stability as: Mn³⁺ < Fe³⁺ < Cr³⁺
() The reduction potentials for the given pairs increase in the following order.

Mn²⁺/ Mn < Cr²⁺/ Cr < Fe²⁺/Fe

So, the oxidation of Fe to Fe²⁺ is not as easy as the oxidation of Cr to Cr²⁺ and the oxidation of Mn to Mn²⁺. Thus, these metals can be arranged in the increasing order of their ability to get oxidised as: Fe < Cr < Mn
() The value for Fe³⁺/Fe²⁺ is higher than that for Cr³⁺/Cr²⁺ and lower than that for Mn³⁺/Mn²⁺. So, the reduction of Fe³⁺ to Fe²⁺ is easier than the reduction of Mn³⁺ to Mn²⁺, but not as easy as the reduction of Cr³⁺to Cr²⁺. Hence, Fe³⁺ is more stable than Mn³⁺, but less stable than Cr³⁺. These metal ions can be arranged in the increasing order of their stability as: Mn³⁺ < Fe³⁺ < Cr³⁺
() The reduction potentials for the given pairs increase in the following order.

Mn²⁺/ Mn < Cr²⁺/ Cr < Fe²⁺/Fe

So, the oxidation of Fe to Fe²⁺ is not as easy as the oxidation of Cr to Cr²⁺ and the oxidation of Mn to Mn²⁺. Thus, these metals can be arranged in the increasing order of their ability to get oxidised as: Fe < Cr < Mn

#17-i
The stability of Fe³⁺ in acid solution as compared to that of Cr³⁺ or Mn³⁺and
Ans : The value for Fe³⁺/Fe²⁺ is higher than that for Cr³⁺/Cr²⁺ and lower than that for Mn³⁺/Mn²⁺. So, the reduction of Fe³⁺ to Fe²⁺ is easier than the reduction of Mn³⁺ to Mn²⁺, but not as easy as the reduction of Cr³⁺to Cr²⁺. Hence, Fe³⁺ is more stable than Mn³⁺, but less stable than Cr³⁺. These metal ions can be arranged in the increasing order of their stability as: Mn³⁺ < Fe³⁺ < Cr³⁺

#17-ii
The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
Ans : The reduction potentials for the given pairs increase in the following order.

Mn²⁺/ Mn < Cr²⁺/ Cr < Fe²⁺/Fe

So, the oxidation of Fe to Fe²⁺ is not as easy as the oxidation of Cr to Cr²⁺ and the oxidation of Mn to Mn²⁺. Thus, these metals can be arranged in the increasing order of their ability to get oxidised as: Fe < Cr < Mn