If 6g of Magnesium is allowed to react with 20 g of oxygen, what mass of magnesium oxide will be produced in the reaction?

Answer 1

2Mg + O₂ ==> 2MgO

moles Mg used = 6 g x 1 mole/24 g = 0.25 moles

moles O₂ used = 20 g x 1 mole/32 g = 0.625 moles

Limiting reactant is Mg

Mass MgO produced = 0.25 mol Mg x 1 mol MgO/mol Mg x 40 g/ mol MgO = 10 g

Answer 2

Magnesium and Oxygen will react to form Magnesium Oxide as per the equation below.

2Mg + O₂ ⇔ 2MgO

Upon close examination, there is a molar ratio of 1 to 1 with respect to Mg to 1 to 2 with respect to MgO.

Given this, the element with the less number of moles will be the limiting reagent. In this instance, it will the the Mg. We will use conversion factors through dimensional analysis to reach the mass of MgO.

6 grams of Mg * ( 1 mol Mg/ 24.31 grams Mg) * (1 mol MgO/1 mol Mg) * (40.31 grams MgO/ 1 mol MgO) = 9.95 g MgO

Therefore, there will be around 10 grams of MgO synthesized.