Question

In the oxidation of oxalic acid by potassium permanganate, in the presence of dil. ${H_2}S{O_4}$ one of the products __________ acts as an autocatalyst.
$A.$ ${K_2}S{O_4}$
$B.$ $MnS{O_4}$
$C.$ $Mn{O_2}$
$D.$ $M{n_2}{O_2}$

Answer 1

$KMn{O_4}$ is an oxidizing agent (oxidizing agent is that which oxidizes another substance and reduces itself). In $KMn{O_4}$ oxidation state of manganese $\left( {Mn} \right)$ is $+ 7$ by oxidizing other substances it reduces to lower oxidation less than $+ 7$ .

Complete answer:
In the oxidation of oxalic acid by potassium permanganate, in the presence of dilute sulphuric acid $\left( {{H_2}S{O_4}} \right)$ . The product acts as an autocatalyst is $MnS{O_4}$ .
The reaction is given as,
$2KMnS{O_2} + 5{H_2}{C_2}{O_4} + 3{H_2}S{O_4} \to 2MnS{O_4} + {K_2}S{O_4} + 10C{O_2} + 8{H_2}O$
In the potassium permanganate titration of oxalic acid in presence of dilute sulphuric acid, It is found that there is slow discharge of the colour of permanganate solution in the beginning but after some time we observe the discharge of the colour become faster. The colour of the discharge becomes faster due to formation of $MnS{O_4}$ during the reaction which acts as a catalyst for the same reaction. Thus we can say that $MnS{O_4}$ is an autocatalyst for this reaction. This is an example of an autocatalyst.

Thus, the correct option is $B.$

Additional information:
Definition of term involved in this question such as oxidation.
Oxidation: It is defined as the loss of electrons during a reaction by a molecule, atom or ion. Oxidation occurs when the oxidation state of a constituent is increased. The opposite process is called reduction, which occurs when there is gain in electrons.

Note:
A chemical reaction is said to be autocatalysis if one of the reaction products is also a catalyst for the same or a coupled reaction. Such a reaction is known as an autocatalysis reaction. Autocatalyst makes the rate of reaction fast.