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

From the equation,mole ratio for the reaction is; $1:1$

Mass of $KC_7H_5O_2=x$

$g C_7H_8=$ $1 mol C_7H_8\over 92.14g/mol$ $\times$ $1mol C_7H_5O_2\over 1mol C_7H_8$ $\times$ $121.11g/mol\over1molKC_7H_5O_2$

$=1.314gC_7H_8$

$\%yield=$ $Actual yield\over Theoretical yield$

$83\%=$ $1.314g\over x$

$x=1.583g$

The mass of $KC_7H_5O_2=1.583g$