# What is the empirical formula of potassium chloride?

Feb 6, 2016

The empirical formula for potassium chloride is $\text{KCl}$.
The empirical formula for a compound is the lowest whole number ratio of elements in one molecule or formula unit of the compound. The chemical formula for an ionic compound such as $\text{KCl}$ is always the same as its empirical formula.
We can determine the empirical formula for potassium chloride by using the charges on the ions. Potassium ions have a $1 +$ charge, and the formula $\text{K"^+}$, and chloride ions have a $1 -$ charge, and the formula $\text{Cl"^(-)}$. All empirical formulas have a net charge of zero. So the ratios of the positive and negative ions must result in an overall charge of zero. In the case of potassium and chlorine, a $1 : 1$ ratio results in a net charge of zero. So the formula for potassium chloride is $\text{KCl}$.
${\text{K"^++"Cl}}^{-}$$\rightarrow$$\text{KCl}$