Aspirin, C₉H₈O₄, Slowly Decomposes at Room Temperature by Reacting with Water

question 79

Multiple Choice

Aspirin, C₉H₈O₄, slowly decomposes at room temperature by reacting with water in the atmosphere to produce acetic acid, HC₂H₃O₂, and 2-hydroxybenzoic acid, C₇H₆O₃ (this is why old bottles of aspirin often smell like vinegar) : C₉H₈O₄ + H₂O $\rarr$ HC₂H₃O₂ + C₇H₆O₃
Concentration and rate data for this reaction are given below. $\begin{array}{ccc}\mathbf{\left[\mathrm{C}_{9} \mathrm{H}_{5} \mathrm{O}_{4}\right](\mathrm{M}) } & \mathbf{\left[\mathrm{H}_{2} \mathrm{O}\right] (M) } & \mathbf{Rate (M/s) } \\\hline 0.0100 & 0.0200 & 2.4 \times 10^{-13} \\0.0100 & 0.0800 & 9.6 \times 10^{-13} \\0.0200 & 0.0200 & 4.8 \times 10^{-13} \\\end{array}$ Write the rate law for this reaction and calculate k (be sure to include the correct units) .

• A) rate = k[C₉H₈O₄][H₂O]², and the rate constant is 1.2 *10^-9 M^-2s^-1 or 1.2 * 10^-9 1/(M² s)
• B) rate = k[C₉H₈O₄], and the rate constant is 1.2 * 10^{-9 -1} or 1.2 * 10^-9 1/ s
• C) rate = k[C₉H₈O₄]²[H₂O], and the rate constant is 1.2 * 10^-9 M^-2s^-1 or 1.2 * 10^-9 1/(M² s)
• D) rate = k[C₉H₈O₄][H₂O], and the rate constant is 1.2 *10^-9 M^-1s^-1 or 1.2 * 10^-9 1/(M s)
• E) None of the above

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