Question

Given below are two statements: 

Statement I: In the oxalic acid vs KMnO$_4$ (in the presence of dil H$_2$SO$_4$) titration the solution needs to be heated initially to 60°C, but no heating is required in Ferrous ammonium sulphate (FAS) vs KMnO$_4$ titration (in the presence of dil H$_2$SO$_4$). 

Statement II: In oxalic acid vs KMnO$_4$ titration, the initial formation of MnSO$_4$ takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs KMnO$_4$, heating oxidizes Fe$^{2+}$ into Fe$^{3+}$ by oxygen of air and error may be introduced in the experiment. 

In the light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is false but Statement II is true
• D. Statement I is true but Statement II is false

Hint:

Always verify the role of temperature and catalysts in redox titrations, as they significantly affect reaction rates and mechanisms.

Answer 1

The Correct Option is A

Statement I:
The titration of oxalic acid with $ KMnO_4 $ in dilute $ H_2SO_4 $ requires initial heating to $ 60^\circ C $. However, the titration of Ferrous Ammonium Sulphate (FAS) with $ KMnO_4 $ under similar conditions does not require heating.

This statement is true.
The reaction between oxalic acid and $ KMnO_4 $ is slow at room temperature, necessitating heating to approximately $ 60^\circ C $ to initiate it. In contrast, the reaction between $ KMnO_4 $ and FAS is rapid even at room temperature.

Statement II:
In the oxalic acid vs $ KMnO_4 $ titration, the initial formation of $ Mn^{2+} $ at high temperatures acts as an autocatalyst for the subsequent reaction. In the FAS vs $ KMnO_4 $ titration, heating could lead to the oxidation of $ Fe^{2+} $ to $ Fe^{3+} $ by atmospheric oxygen, causing experimental errors.

This statement is also true.
In the oxalic acid titration, the reaction rate increases as the reaction progresses due to the autocatalytic effect of the formed $ Mn^{2+} $ ions. Initial heating is required to overcome the slow start.
In the FAS titration, heating might cause aerial oxidation of $ Fe^{2+} $ to $ Fe^{3+} $, which would compromise the accuracy of the titration.

Conclusion:
Both Statement I and Statement II are true.

Final Answer:
The final answer is $ \ \text{Both Statement I and Statement II are true} $.