Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). b. HCHO₂

Key Concepts

Strong vs. Weak Acids

Strong acids completely dissociate in water, releasing all their protons (H+), while weak acids only partially dissociate. This distinction is crucial for understanding acid behavior in solution, as strong acids have a high concentration of H+ ions, leading to a lower pH, whereas weak acids have a higher pH due to their incomplete dissociation.

Acid Ionization Constant (Ka)

The acid ionization constant (Ka) quantifies the strength of a weak acid by measuring the extent of its dissociation in water. It is defined by the equilibrium expression: Ka = [H+][A-]/[HA], where [H+] is the concentration of hydrogen ions, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the undissociated acid. A larger Ka value indicates a stronger weak acid.

Formic Acid (HCHO2)

Formic acid (HCHO2) is a weak acid commonly used in various applications, including food preservation and as a chemical reagent. Its weak nature means it does not fully dissociate in solution, and thus, its ionization can be represented by the equilibrium expression for Ka. Understanding its classification as a weak acid is essential for predicting its behavior in chemical reactions and solutions.