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 (mm = 70.90 g/mol) reacts with 5.00 g of potassium (mm = 39.10 g/mol) to form potassium chloride. the reaction is

The reaction between chlorine gas (Cl2) and potassium (K) in order to form potassium chloride (KCl) is written below.

                                                                                2K + Cl2 à 2KCl

We are to calculate the amount of product produce per given mass of reactant.

(7 g of chlorine gas)

                                (7 g Cl2) x (1 mol Cl2/70.90 g Cl2) x (2 mol KCl/1 mol Cl2) = 0.197 mols Cl2

(5 g of potassium)

                                (5 g K) x (1 mol K/39.10 g K) x (2 mol KCl/2 mol K) = 0.127 mols Cl2

Since, the calculate mols of Cl2 for 5 g of potassium is lesser then, the limiting reactant is potassium.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.