Question

Which statement is true about limiting reactants?

Answer 1

Ans: B). The limiting reactant in a reaction is the first reactant to be completely converted to products.

In a chemical reaction, the limiting reagent is one with a lower number of moles. Thus, the limiting reactant will be consumed first and will dictate the amount of product that can be formed.

For example consider the reaction between 1 g of Mg and 2 g of O to form MgO

$2Mg + O_{2} ---- 2MgO$

# moles of Mg = $\frac{mass of Mg}{atomic mass of Mg} = \frac{ 1 g}{24 g.mol-1} = 0.042 moles$

# moles of Oxygen = $\frac{mass of oxygen}{molar mass} = \frac{2}{32} =0.063 moles$

since moles of Mg is less than that of oxygen, Mg will be the limiting reactant. Thus, it will be consumed first and will be completely converted into MgO.

Answer 2

B). The limiting reactant in a reaction is the first reactant to be completely converted to products.

Hope this helps you.