Answer to Question #144725 in General Chemistry for Mikkos Joshua Garcia

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)

What mass of C7H8 is needed to produce 11.4 g of KC7H5O2, assuming a yield of 65%?

Answer 1

Molar mass C₇H₈ = 92.14 g/mol

Molar mass KC₇H₅O₂ = 160.21 g/mol

 Percent yield = Actual yield/Theoretical yield × 100%

Theoretical yield  of KC₇H₅O₂ = actual yield/percent yield × 100% = 11.4g/65% × 100% = 17.54 g KC₇H₅O₂

According to the reaction equation from 1 mol of C₇H₈ be produced 1 mole of KC₇H₅O₂.

Mass of C₇H₈ = 17.54g KC₇H₅O₂/160.21g/mol KC₇H₅O₂ × 92.14g/mol C₇H₈ = 10.09 g C₇H₈

Answer: mass of C₇H₈ is 10.09 grams.