Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride.
A)Potassium is the limiting reactant; 2.47 g of chlorine remain.
B)Potassium is the limiting reactant; 7.23 g of chlorine remain.
C)Chlorine is the limiting reactant; 4.64 g of potassium remain.
D)Chlorine is the limiting reactant; 2.70 g of potassium remain.
E)No limiting reagent: the reactants are present in the correct stoichiometric ratio.

Question

Quizplus · Accepted Answer

The balanced chemical equation for the reaction is $2K + Cl_2 \rightarrow 2KCl$. From the molar masses, we can calculate the moles of each reactant: $5.00 \, \text{g K} \times \frac{1 \, \text{mol K}}{39.10 \, \text{g K}} = 0.128 \, \text{mol K}$ and $7.00 \, \text{g Cl}_2 \times \frac{1 \, \text{mol Cl}_2}{70.90 \, \text{g Cl}_2} = 0.099 \, \text{mol Cl}_2$. The stoichiometry requires 1 mole of $Cl_2$ for every 2 moles of K, so potassium is in excess. Using the stoichiometry of the reaction, the remaining amount of chlorine can be calculated, leading to the conclusion that potassium is the limiting reactant and 2.47 g of chlorine remain unreacted.

Potassium Chloride Is Used as a Substitute for Sodium Chloride