Question

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) ?

Answer 1

`0.33` moles of `O_2`

Explanation:

1. Locate `Mg` 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 Mg=(mass)/(at. mass)`
   `n Mg=0.67 mol`
3. Then, compute the number of moles of `O_2` needed to completely react with magnesium through conversion method;
   `0.67 cancel(mol Mg)`x`(1 mol O_2)/(2 cancel(mol Mg))`
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`