Elemental analysis of the complex bio-macromolecule peroxidase anhydrous enzyme reveals that it cont — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
Elemental analysis of the complex bio-macromolecule peroxidase anhydrous enzyme reveals that it contains exactly $0.5\%$ by weight of the heavy metal Selenium ($Se$). Assuming no other heavy metals are present, what is the absolute minimum molecular weight of this specific enzyme? (Atomic weight of $Se = 78.4$)
💡 Solution & Explanation
Step 1: Understand the theoretical premise of "minimum molecular weight". This calculation rigidly assumes the presence of at least one single atom of the specified element (Selenium) per molecule of the complex compound. Step 2: Establish the mass relationship. Therefore, 1 mole of the enzyme must contain at least 1 mole of Se atoms, which weighs $78.4\text{ g}$. Step 3: Utilize the given percentage. This $78.4\text{ g}$ strictly represents $0.5\%$ of the total minimum molar mass ($M$). $0.5\% \text{ of M} = 78.4 \Rightarrow \left(\frac{0.5}{100}\right) \times M = 78.4$. Step 4: Solve for M. $M = \frac{78.4 \times 100}{0.5} = 15680 = 1.568 \times 10^4\text{ g mol}^{-1}$.