Question

Calculate the mass of $\text{Mg} \, \left(\text{atomic} \, \text{mass} \, \text{=} \, \text{24} \, \text{g/mol}\right)$ that combines with $1.5$ mol of $O_{2}$ to form magnesium oxide $\left(M g O\right)$ .

• A. $24$ $g$
• B. $36$ $g$
• C. $48$ $g$
• D. $72$ $g$

Answer 1

Answer: (D)

$\underset{\text{1} \, \text{mole}}{\text{Mg}} \, \text{+} \, \underset{\text{0} \text{.5} \, \text{mole}}{\frac{\text{1}}{\text{2}} \text{O}_{\text{2}}} \rightarrow \text{MgO}$
$0.5$ $mole$ of oxygen react with $\text{1}$ mole of $\text{Mg}$
$1.5$ $mole$ of oxygen react with $\frac{1.5}{0.5}=3$ mole
$24\times 3=72$ $gm$ .