What is the pH of H2O2 solutions?
It depends upon a number of factors discussed below. But first … a few points on what pH means. pH is a logarithmic measure — pH = log10 1/[H+]. Hence, if you mix equal parts of a pH 2 solution and pH 4 solution, you will not necessarily end up with a pH 3 solution – Reason No. 1: According to the definition of pH, the pH 2 solution has 100 times the concentration of hydrogen ion [H+], not twice the concentration. Reason No. 2: Both the pH 2 solution and pH 4 solution may contain “buffering agents” which dampen shifts in pH despite the addition of acids or bases. Hence, to anticipate the resulting pH, it is useful to measure the relative buffering capacities of the two solutions in addition to their pH. The measures used to define buffering capacity (acidity and alkalinity) are derived from the amount of acid or base needed to bring the solutions to neutrality (pH 7). With this background, the following factors influence the pH of commercial solutions of H2O2: • Industrial strength
