Final answer:
To calculate the pH of a buffer, the Henderson-Hasselbalch equation is used; however, without the pKa value of amphetamine, an accurate pH cannot be determined. Assuming all amphetamine is converted to its conjugate acid by excess perchloric acid, the solution may be acidic.
Step-by-step explanation:
The question asks us to calculate the pH of a buffer solution created by mixing a weak base, amphetamine (ampd), with its conjugate acid, perchloric acid (HClO4). A buffer works to maintain pH stability upon the addition of small amounts of acid or base. The calculation requires the Henderson-Hasselbalch equation:
\(pH = pKa + \log\left(\frac{{[base]}}{{[acid]}}\right)\)
In this case, without the pKa of amphetamine provided, we cannot compute the pH directly. However, given that perchloric acid is a strong acid, it will completely dissociate in water, converting all of the amphetamine to its conjugate acid form. Hence, the buffer capacity may be compromised as there might not be sufficient base left to react with added acids or bases. The pH would thus depend on the extent of the reaction between ampd and HClO4 and could be more accurately calculated with a full knowledge of the reaction's equilibrium.
To fully answer this question, one would need the pKa of amphetamine. In absence of this information, we could assume the mixture is more acidic due to excess HClO4, and the pH would likely be below 7.