Ladder diagrams are graphical representations useful for evaluating the chemistry of a given system during analysis. A Ladder diagram used for assessing the reactivity of acids and bases consists of a vertical line of pH scale and a short horizontal line that correlates to the pH equal to the pKa value, separating the solution into two regions. Consider the reaction between the HF and F−. At equilibrium, the HF and F− concentrations are equal, and the pH value equals its pKa of 3.17. The ladder diagram shows a higher concentration of HF at pH values below its pKa, whereas the concentration of F− dominates above this. Similarly, the HF and NH3 system ladder diagram shows another horizontal line at the pH equal to pKa, NH3 of 9.24. HF and NH4+ species dominate at the pH values below the HF pKa value of 3.17. However, if the pH values are between 3.17 and 9.24, the NH4+ and F− species dominate, and above 9.24, F− and NH3 species predominate.