22 Anatomy & Physiology Coloring Workbook 16. Using the key choices, fully characterize weak and strong acids. Key Choices A. Ionize completely in water E. Ionize at high pH B. lonize incompletely in water F. Ionize at low pH C. Act as part of a buffer system G. Ionize at pH7 D. When placed in water, always act to change the pH

**Strong Acids:**<br /><br />* **A. Ionize completely in water:** This is the defining characteristic of a strong acid. Every molecule of the acid dissociates into its component ions (e.g., H+ and Cl- for hydrochloric acid).<br />* **D. When placed in water, always act to change the pH:** Because they release a high concentration of H+ ions, strong acids significantly lower the pH of a solution.<br />* **F. Ionize at low pH:** While technically true, this is a consequence of their ionization, not a defining characteristic. They *create* a low pH environment.<br /><br />**Weak Acids:**<br /><br />* **B. Ionize incompletely in water:** Only a small percentage of weak acid molecules dissociate into ions. The remaining molecules stay intact in solution.<br />* **C. Act as part of a buffer system:** Weak acids and their conjugate bases are essential components of buffer systems, which help resist changes in pH.<br />* **D. When placed in water, always act to change the pH:** Although weak acids don't ionize completely, they still release some H+ ions and therefore lower the pH, though to a lesser extent than strong acids. The pH change is less dramatic than with strong acids.<br />