Question

Question 8.12 How do you count for the following observations?

(a) Though alkaline potassium permanganate and acidic potassium permanganate both are used as oxidants, yet in the manufacture of benzoic acid from toluene we use alcoholic potassium permanganate as an oxidant. Why? Write a balanced redox equation for the reaction.

(b) When concentrated sulphuric acid is added to an inorganic mixture containing chloride, we get colourless pungent smelling gas HCl, but if the mixture contains bromide then we get red vapour of bromine. Why?

Class XI Redox Reactions Page 273

Answer 1

(a) (A) oxidation of toluene to Benzoic acid in acidic medium . see attachment , figure A shows the reaction .

(B) oxidation of toluene to Benzoic acid in basic medium and neutral medium. see attachment figure B shows the reaction.

on industrial scale , alcoholic potassium permanganate is preferred to acidic medium or basic potassium permanganate because in the presence of alcohol both reactants KMnO4 and CuH5CH3 are mixed very well and form homogeneous solution and in homogeneous medium reaction takes place faster than in heterogeneous medium . but in neutral medium OH- ions are produced in the reaction itself.

(b) Let see first of all reactions of these.
2NaCl (inorgainc chloride)+2H2SO4(sulphuric acid) ----> 2NaHSO4 + 2HCl

here, HCl is formed but we know, HCl is weak reducing agent.it can't reduce H2SO4 to SO2 .that's why we get pungent smelling of gas HCl is obtaining.

again, if the mixture containing Br
e.g., 2NaBr + 2H2SO4 ------->2NaHSO4 + 2HBr
further , 2HBr + H2SO4 ---->Br2↑ + SO2↑ + 2H2O

Here , HBr is strong reducing agent [ because Br is bigger than Cl and Br has tendency to loss electron ] it reduces H2SO4 to SO2 and is itself oxidised to Br2 . That's why we get red vapor of Br when Conc. H2SO4 reacts with inorgainc mixture containing Bromine salt.

Answer 2

Answer:

see the answer.

Explanation:

correct answer is here✌