How to calculate the hydronuim ion cencentration of solution with a pH of 2.5?
pH = -log(H^+)
2.50 = -log(H^+)
-2.50 = log(H^+).
Punch in -2.50 on your calculator (or punch in 2.50 and change the sign to -), then hit the 10x key. It should return 3.16227E-3 which will round to 3.16E-3.