What is the pH of 0.2004M of HNO3 It's an acid?

The definition of pH is the -log[H⁺], which basically means the negative common log (base 10) of the concentration of hydronium ions in solution. Since nitric acid is a strong monoprotic acid (one H⁺) it makes the problem so much easier since there is no acid equilibrium to deal with. Since there is one H⁺ for every acid molecule thus the [H⁺], or concentration of H⁺, is equal to the concentration of the acid, which is given to be 0.2004M. Thus, pH = -log[H⁺] = -log(0.2004) = (with sig figs) 0.6981 pH, something you really don't want to stick your hand in, but not as bad as some acid I've seen (yay, negative pH!).

First answer by Rosencrantz. Last edit by Rosencrantz. Contributor trust: 125 [recommend contributor]. Question popularity: 1 [recommend question]