eng Science and Education Publishing World Journal of Chemical Education 2375-1657 2026-08-09 14 3 47 50 10.12691/wjce-14-3-2 WJCE20261432 article V. Jagannadham 1 Sanjeev Rachuru 2 D. A. Padmavathi 2 Department of Chemistry, Osmania University, Hyderabad-500007, India Department of Chemistry, St. Ann's College for Women, Mehdipatnam Hyderabad-500028, India Water (HOH), hydroxyl radical (HO), hydroxide ion (HO), hydrogen peroxide (HHO2), hydroperoxyl radical HO2 hydroperoxide anion HO2 and hydronium ion (HH2O+) are all water related species and are environmentally important. The corresponding acid -base couples are represented as HOH/OH, HO/O, HO/O2, HHO2/, HO2/ O2-, HO2/ O22 and H3O+/H2O. Therefore, the corresponding conjugate bases are hydroxide ion OH, mono oxygen radical anion O, oxide dianion O2, hydroperoxide anion HO2, peroxyl radical anion O2-, peroxide dianion O22 and H2O respectively. The acid-base properties are well characterized by treating the pKa data with Taft * values of the corresponding conjugate bases of these couples using Taft linear free-energy relationship (LFER). Positive Taft * value of 17.7 indicates that electron withdrawing species facilitate the deprotonation and vice-versa. The present study is a good class-room exercise for both undergraduate and graduate advanced physical-organic chemistry level. https://pubs.sciepub.com/wjce/14/3/2/wjce-14-3-2.pdf Species of water Taft equation