**Passage 7:** What is the **percentage of free ** in a oleum sample? — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question

💡 Solution & Explanation

$18\text{ g } H_2O = 1 \text{ mole}$. <br>Requires $1 \text{ mole } SO_3 = 80 \text{ g}$. <br>In $100\text{ g}$ oleum, there is $80\text{ g } SO_3$, which is $80\%$.