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

Verified step by step guidance

1. insert step 1: Identify the acid in question, which is formic acid (HCHO2).
2. insert step 2: Recall that strong acids completely dissociate in water, while weak acids only partially dissociate.
3. insert step 3: Recognize that formic acid (HCHO2) is a weak acid because it does not completely dissociate in water.
4. insert step 4: Write the balanced chemical equation for the ionization of formic acid: HCHO2 (aq) ⇌ H+ (aq) + CHO2- (aq).
5. insert step 5: Write the expression for the acid ionization constant (Ka) for formic acid: Ka = [H+][CHO2-] / [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.