Exactly of Potassium chlorate () is thermally decomposed completely. The entire volume of oxygen gas — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
Exactly $1.0\text{ mole}$ of Potassium chlorate ($KClO_3$) is thermally decomposed completely. The entire volume of oxygen gas produced is then used to burn an excess of aluminium powder. How many moles of Aluminium oxide ($Al_2O_3$) are formed in the final step?
💡 Solution & Explanation
Step 1: Decomposition reaction. $2KClO_3 \rightarrow 2KCl + 3O_2$. From the stoichiometry, $2\text{ moles}$ of $KClO_3$ yield $3\text{ moles}$ of $O_2$. Therefore, $1.0\text{ mole}$ of $KClO_3$ yields exactly $1.5\text{ moles}$ of $O_2$. Step 2: Combustion reaction. $4Al + 3O_2 \rightarrow 2Al_2O_3$. The stoichiometry requires $3\text{ moles}$ of $O_2$ to produce $2\text{ moles}$ of $Al_2O_3$. Therefore, the $1.5\text{ moles}$ of $O_2$ available will produce exactly $1.0\text{ mole}$ of $Al_2O_3$.