Abstract The 2024 high school chemistry textbook revised the “inquiry experiment on hydrolysis of ferric chloride” to the “inquiry experiment on hydrolysis of ferrous sulfate”. This study reviews domestic and international literature to explore the mechanisms by which chloride ions and sulfate ions influence the hydrolysis equilibrium of ferric ions. Findings reveal that chloride ions inhibit iron(III) hydrolysis through coordination interactions, causing abnormal solution coloration due to yellow complex formation that obscures direct observation of experimental phenomena. Conversely, sulfate ions—despite stronger coordination ability—form pale (nearly colorless) complexes and promote iron(III) precipitation. Therefore, substituting ferric sulfate for ferric chloride avoids color interference, better meeting the requirements of teaching observation and experimental design. This study provides theoretical support for textbook revision and deepens the understanding of anion effects on the hydrolysis behavior of ferric ions.
ZHANG Qian-Yong, LI Gui-Xin. Literature Review on Influence of Chloride, Sulfate, and Nitrate Ions on Hydrolysis Equilibrium of Ferric Ions[J]. Chinese Journal of Chemical Education, 2026, 47(7): 102-110.
