Question

wil the purple color due to potassium permanganate ever be discharged if 2g of chlorotoluene are mixed with 7.3g of potassium permanganate (wanter and NaOH) have also been added) and the reaction is heated under reflux for 3 hours?

Answer 1

Answer – We are given that 2g of chlorotoluene are mixed with 7.3g of potassium permanganate.

We know the reaction between the chlorotoluene and potassium permanganate

C₇H₇Cl + KMnO₄ + water /heat ------> C₇H₅O₂Cl + MnO₂ + KOH

So, moles of C₇H₇Cl = 2.0 g / 126.59 g.mol^-1

                                   = 0.0158 moles

We know

1 moles of C₇H₇Cl = 1 moles of KMnO₄

So, 0.0158 moles of C₇H₇Cl = ?

= 0.0158 moles of KMnO₄

So, mass of KMnO₄ = 0.0158 moles * 158.034 g/mol

                                 = 2.50 g of KMnO₄

So for the complete reaction with 2.0 g of chlorotoluene we need only 2.5 g of KMnO₄ and we are given the excess mass of KMnO₄, so there is purple color due to potassium permanganate not discharged. In the solution there is purple color and this can be eliminate using the NaHCO_3.