Using your data, explain a possible reason for the pH of the HCl solution that you made not matching the correct pH assuming you made no errors in creating the solution.

Question

We were given a pH of 2.9 and when we made the solution and took the pH of the solution we got a pH of 4.7.

Answer 1

Perhaps the hydrochloric acid, or HCl, which is notably a strong acid dissociated a bit and/or interacted with water in a way where rather than producing greater quantities of hydronium ions, H₃O⁺, also called hydrogen protons, H+, which would presumably decrease the pH by nature, instead the reaction somehow involved the water acting as a base increasing hydroxide ion concentration.

Another way of thinking about this may be related to the concept of dilution whereby increasing the concentration of water in the solution will dilute the solution by reacting with Hydrochloric Acid, HCl, which normally has a pH of around 2. the pH of water ranges from around 6.5 to 8.5. Interestingly, a pH of 7 is typically chosen as indicative of neutrality balanced between acidic and alkaline.