Video Transcript
Potassium chloride is widely used
as a fertilizer. It can be made by the reaction of
potassium metal with chlorine gas. What is the correct, balanced
chemical equation for this reaction? (A) K plus Cl forms KCl, (B) K plus
Cl2 forms KCl2, (C) K2 plus Cl2 forms two KCl, (D) two K plus Cl forms K2Cl, or (E)
two K plus Cl2 forms two KCl.
So, the reaction is between
potassium metal and chlorine gas. Potassium metal has the chemical
symbol K. Chlorine gas exists as a diatomic
molecule and has the formula Cl2. The metal potassium and nonmetal
chlorine react to form potassium chloride. When potassium reacts, it tends to
form one plus ions. And when chlorine reacts, it tends
to form one minus ions. Therefore, the chemical formula of
potassium chloride is KCl.
The chemical formulas for each
species are correct, but the equation needs to be balanced. The chlorine atoms are unbalanced
as there are two on the left side of the equation and one on the right. Therefore, to balance the chlorine,
there should be two equivalents of potassium chloride. Although the number of chlorine
atoms is now balanced, the number of potassium atoms is unbalanced, as there are two
atoms of potassium on the right of the equation and one on the left. Therefore, there should be two
equivalents of potassium metal. The equation is now balanced.
Therefore, the correct balanced
chemical equation for this reaction is two K plus Cl2 forms two KCl, or answer
choice (E).
