Question

The aspirin substitute, acetaminophen (C₈H₉O₂N), is produced by the following three-step synthesis: I. C₆H₅O₃N(s)+ 3H₂(g)+ HCl(aq) ⟶ C₆H₈ONCl(s) + 2H₂O (l) II. C₆H₈ONCl(s)+ NaOH(aq) ⟶ C₆H₇ON(s) +H₂O(l) + NaCl (aq) III. C₆H₇ON(s) + C₄H₆O₃(l) ⟶ C₈H₉O₂N(s) + HC₂H₃O₂ (l) The first two reactions have percent yields of 87% and 98% by mass, respectively. The overall reaction yields 3 moles of acetaminophen product for every 4 moles of C₆H₅O₃N reacted. What is the percent yield by mass of Step III?

Answer 1

The percent yield by mass of Step III is approximately 18.36%.

The overall reaction states that 4 moles of C₆H₅O₃N yield 3 moles of C₈H₉O₂N. Hence, 3.41x moles of C₈H₉O₂N correspond to 3 moles of C₈H₉O₂N.

Solving for x gives: x = 3 / 3.41

= 0.88.

molar mass of C₈H₉O₂N (151.17 g/mol) to find the actual mass of acetaminophen: 0.88 * 151.17 g/mol = 133.04 g.

4 moles of C₆H₅O₃N (molar mass 181.14 g/mol),

the theoretical mass of the product would be:

4 * 181.14 g/mol = 724.56 g.

We then divide the actual mass of acetaminophen by the theoretical mass and multiply by 100%:

(133.04 g / 724.56 g) * 100%

= 18.36%.