Ladderdiagrammen: zuur-base-evenwichten

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 pK_a 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 pK_a of 3.17.

The ladder diagram shows a higher concentration of HF at pH values below its pK_a, 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 pK_{a, 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.