Question

which choice identifies the correct limiting reactant and correct reasoning?
2mg + o₂ → 2mgo
2.40 g mg theoretically yields 3.98 g mgo.
10.0 g o₂ theoretically yields 25.2 g mgo.
o₂ because it has the higher initial mass
mg because it has the lower initial mass
mg because it has the lower theoretical yield
o₂ because it has the higher theoretical yield

Explanation:

To determine the limiting reactant, we compare the theoretical yields of the products from each reactant. The limiting reactant is the one that produces the smaller amount of product because it will be completely consumed first, limiting the amount of product formed. Here, Mg produces 3.98 g of MgO, and O₂ produces 25.2 g of MgO. Since 3.98 g (from Mg) is less than 25.2 g (from O₂), Mg is the limiting reactant because it has the lower theoretical yield. The initial mass of the reactant is not the determining factor for the limiting reactant; it's the amount of product each can produce.

Answer:

Mg because it has the lower theoretical yield