Question

Why is the mixture of the titration of potassium permanganate solution using oxalic acid heated before titration? ​

Answer 1

The mixture of the titration of potassium permanganate solution using oxalic acid heated before titration to make the temperature optimum for the reaction to take place.

Explanation:

• The optimum temperature for reaction of  and oxalic acid is 60-70 degree Celsius

• If the temperature is low, then the reaction between                                will be too slow.

• If temperature is above optimum then oxalic acid decomposes to give CO2

• Under optimum temperature, the reactants receive enough activation energy to start the reaction

• If the mixture is heated, due to increased kinetic energy of particles effective collision will take place.

• This will increase the rate of reaction.

Answer 2

Explanation:

During titration of oxalic acid and $KMnO_4$ in acid medium to reaction is extremely slow. Since$KMnO_4$ is acting as a self indicator the colour disappears after less than 30s even after approaching equivalent point. So the reaction mixture is heated to approximately 70–$80^0 C$ (just before it starts boiling) and the titration is started. This helps in initiating the reaction via supplying the necessary activation energy of the reaction.  Secondly the heat helps to decompose $[Mn(C_2O_4)^3]^{-3}$complex which forms as a result of local excess of $KMnO_4$.the complex is unstable above $60^0C$ and the $Mn^{+2}$ formed as a result catalyses the rest of the reaction. Thirdly the temp should never exceed the range given as oxalic acid will decompose above this temp to $Co_2$