The purpose of the current experiment was to determine the pH of various hydrochloric acid and acetic acid solutions, to determine the pH of various salt solutions, to prepare a buffer solution, and determine the effects of adding a strong acid and strong base to the buffer solution versus adding a strong acid and strong base to water. The measured pHs for the hydrochloric acid solutions were 1.6, 2.2, 2.9, and 3.8. The measured pHs for the acetic acid solutions were 2.9, 3.9, 4.2, and 4.4. The pHs measured for the salts were 4.3 for sodium chloride, 7.3 for sodium acetate, 8.9 for sodium bicarbonate, 10.8 for sodium carbonate, 7.9 for ammonium chloride, and 6.9 for ammonium acetate. The pH for the buffer solution and the strong acid was 3.9 and the pH for the buffer solution and the strong base was 11.6. The pH of water with the strong acid added was 3.44 and the pH of water with the strong base added was 13.4
Water is a polar molecule, meaning many compounds readily dissolve in it forming aqueous solutions. The water molecules surround the molecules or ions in the solution for dissolution. In other cases, the water molecules react with the solute molecules or solute ions. In pure water, a small amount of molecules take part in an equilibrium reaction1.
2 H2O (l) H3O+ (aq) + OH- (aq)
This self-ionization of water produces a small amount of both hydronium and hydroxide ions. The equilibrium constant expression for this reaction is called Kw (1.0x10-14), or the ion product of water1. From this number, if the concentration of hydronium is known the concentration of hydroxide can be found or vice versa.
Strong acids are substances that ionize completely in water and produce hydronium ions. Therefore, if a strong acid is added to a solution, the concentration of hydronium is equal to the original concentration of acid added to the solution. A strong base is a substance