Final answer:
To calculate the theoretical yield of MgO in an experiment where magnesium is the limiting reactant, one must use stoichiometry to find the number of moles of Mg and then convert those moles to grams of MgO. The percent yield is the ratio of the actual yield to the theoretical yield multiplied by 100.
Step-by-step explanation:
Calculating Theoretical Yield and Percent Yield of MgO
To determine the theoretical yield of MgO when magnesium is the limiting reactant, you must first identify the balanced chemical equation for the reaction of magnesium with oxygen, which is 2Mg + O₂ → 2MgO. Now, you would calculate the number of moles of magnesium used in the experiment based on its mass and molar mass. After that, using the molar ratio from the equation, you can calculate the number of moles of MgO that should form. To find the mass of the theoretical yield, multiply the moles of MgO by its molar mass.
The percent yield of MgO is calculated by dividing the actual yield obtained in the experiment by the theoretical yield and multiplying by 100. A general formula for percent yield is:
Percent Yield = (Actual Yield / Theoretical Yield) x 100%
Remember that the value you obtained for the theoretical yield is based on the limiting reactant, which is magnesium in this case, as it produces less MgO compared to oxygen, making it the limiting reagent.