Question

Potassium benzoate (KC7H5O2) is another food preservative that inhibits the growth of mold, yeast and some bacteria. It is one of the products of the reaction between toluene, C7H8 and potassium permanganate, KMnO4.
C7H8(l) + 2KMnO4(aq) ➡️ KC7H5O2(aq) + 2MnO2(s) + KOH(aq) + H2O(l)

1. If the percentage yield is 83%, what mass of KC7H5O2 can be expected?

Answer 1

Now, the information is not complete as there should be the mass of at least one substrate in the question,

So let's assume the mass of Potassium permanganate is 158g

From the reaction,

1mole of $KMnO_4$ produces 1 mole of $KC_7H_5O_2$

158g of KMnO₄ = 1 mole of KMnO₄.

Therefore 1 mole of potassium benzoate is produced.

1 mole of potassium benzoate = 160g.

Therefore, theoretical yield = 160g

Actual yield = Theoretical yield/100% × %yield

= 160g/100% × 83%

= 132.8g

Therefore, when 158g of potassium permanganate is used in the reaction, 132.8g of potassium benzoate is produced.