Abstract Water is essential for all living organisms. The physical and chemical properties of water are central to all biological structure and function. The ionization ability of water to form H+ and OH- ions make it very unique. The hydrogen-ion concentration of biological system is usually preferred as the pH system, which determines the pH level of dilute aqueous solutions. In this laboratory exercise, the data collected from the titration of weak acids with a …showed first 75 words of 642 total…

…showed last 75 words of 642 total…compared these values with Acetic acid, Glycin, Histindine, and Glutamic acid pKa(s) and we found the pH of the unknown acid was very close to the first, second, and third pKa(s) of Histidine (1.77, 6.0, 8.29) or the approximate pH value of Histidine is 5.35, therefore, we assumed that the unknown acid was Histidine. Titration of Acetic acid, Glycin, Histidine, Glutamic acid, and Unknown acid data KOH (ml) Acetic acid Glycin Histidine Glutamic acid Unknown acid 02.621.701.540.970.65 23.081.761.641.070.74 33.431.861.771.190.81 43.741.931.921.330.91 53.962.022.141.481.02 64.152.132.551.651.15 74.332.254.121.841.34 84.532.454.862.081.66 94.732.675.192.342.49 104.962.965.452.644.32 115.703.985.642.924.83 125.718.555.833.145.41 1310.389.066.003.395.67 1411.769.326.193.595.90 1512.049.576.373.826.16 1612.209.757.004.076.45 1712.309.947.654.386.98 1812.4110.128.297.757.87 1912.4810.308.688.328.46 Table 1