Elemental analysis of the highly complex, macro-biomolecule peroxidase anhydrous enzyme reveals that — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
Elemental analysis of the highly complex, macro-biomolecule peroxidase anhydrous enzyme reveals that it contains exactly $0.5\%$ by weight of Selenium ($Se$). Assuming no other heavy metals are present, what is the absolute minimum molecular weight of this enzyme? (Atomic weight of $Se = 78.4$)
💡 Solution & Explanation
The concept of "minimum molecular weight" operates on the assumption that a single molecule of the compound must contain at least one complete atom of the specified element. Therefore, the mass of Se in one mole of the enzyme is at least $78.4\text{ g}$. This $78.4\text{ g}$ constitutes exactly $0.5\%$ of the total molar mass ($M$) of the enzyme. $\frac{0.5}{100} \times M = 78.4 \Rightarrow M = \frac{78.4 \times 100}{0.5} = 78.4 \times 200 = 15680$. Expressed in scientific notation, the minimum molecular weight is $1.568 \times 10^4\text{ g/mol}$.