Question

How many grams of magnesium oxide can be produced when 125 g Mg react with 102 g O2?

Unbalanced equation: Mg + O2 → MgO

Show, or explain, all of your work along with the final answer.

Answer 1

The balanced equation is

`Mg+ (1)/(2) O_(2)---> MgO`

Thus as per equation, one mole of Mg will react with half mole of oxygen to give one mole of MgO

The moles of Mg present will be calculated as

Moles = mass / Atomic mass of Mg = 125g / 24 = 5.2 moles

moles of oxygen present = mass / molar mass of oxygen = 102 / 32 = 3.2 moles

5.2 moles of Mg will react with 2.6 moles of oxygen to give 5.2 moles of MgO

[Here Mg is limiting reagent]

Moles of MgO obtained = 5.2 moles

Mass of MgO produced = moles X molar mass = 5.2 X 40 = 208 g