Class 12 Chemistry - Chapter The d-and f-Block Elements NCERT Solutions | For M2+/M and M3+/M2+ systems, the E⊖&

Welcome to the NCERT Solutions for Class 12th Chemistry - Chapter The d-and f-Block Elements. This page offers a step-by-step solution to the specific question from Excercise ".$ex_no." , Question 17: for m2 m and m3 m2 systems the e nbsp valu....

Question 17

For M²⁺/M and M³⁺/M²⁺ systems, the E^⊖ 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:

(i) The stability of Fe³⁺in acid solution as compared to that of Cr³⁺or Mn³⁺ and

(ii) The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.

Answer

(i) The E^⊖ 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⁺

(ii) 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 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+ (ii) 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

Recently Viewed Questions of Class 12 Chemistry

Q:-

The following results have been obtained during the kinetic studies of the reaction: 2A + B → C + D

Experiment	A/ mol L^{- 1}	B/ mol L^{- 1}	Initial rate of formation of D/mol L^{- 1} min^{- 1}
I	0.1	0.1	6.0 × 10^{- 3}
II	0.3	0.2	7.2 × 10^{- 2}
III	0.3	0.4	2.88 × 10^{- 1}
IV	0.4	0.1	2.40 × 10^{- 2}