Science, Tech, Math › Science Acids and Bases: Calculating pH of a Strong Acid Calculate the pH of a Hydrobromic Acid (HBr) Solution Share Flipboard Email Print Anchalee Phanmaha / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated November 14, 2019 A strong acid is one that completely dissociates into its ions in water. This makes calculating the hydrogen ion concentration, which is the basis of pH, easier than for weak acids. Here's an example of how to determine the pH of a strong acid. pH Question What is the pH of a 0.025 M solution of hydrobromic acid (HBr)? Solution to the Problem Hydrobromic Acid or HBr is a strong acid and will dissociate completely in water to H+ and Br-. For every mole of HBr, there will be 1 mole of H+, so the concentration of H+ will be the same as the concentration of HBr. Therefore, [H+] = 0.025 M. pH is calculated by the formula pH = - log [H+] To solve the problem, enter the concentration of the hydrogen ion. pH = - log (0.025)pH = -(-1.602)pH = 1.602 Answer The pH of a 0.025 M solution of Hydrobromic Acid is 1.602. One quick check to make sure your answer is reasonable is to verify the pH is closer to 1 than to 7 (certainly not higher than this.) Acids have a low pH value. Strong acids typically range in pH from 1 to 3.