# How many moles of oxygen are required to completely react with 16.1 grams of magnesium metal according to the equation: 2 Mg(s) + O2(g) → 2 MgO(s) ?

Mar 14, 2016

$0.33$ moles of ${O}_{2}$

#### Explanation:

1. Locate $M g$ in the periodic table and take note of the atomic mass;
2. Find the number of moles of magnesium by dividing the mass as provided in the problem against the atomic mass of magnesium;
$n M g = \frac{m a s s}{a t . m a s s}$
$n M g = 0.67 m o l$
3. Then, compute the number of moles of ${O}_{2}$ needed to completely react with magnesium through conversion method;
$0.67 \cancel{m o l M g}$x$\frac{1 m o l {O}_{2}}{2 \cancel{m o l M g}}$
4. Make sure to cancel out units that are not needed leaving only the desired units;
5. The final answer is found to be $0.33$ moles of ${O}_{2}$