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 $\left(MgO\right)$ .

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

Answer 1

Answer: (D)

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