How do you determine the pH of a substance with an H+ concentration of 3.2 x 10^-3? Thanks in advance!

pH = -log(H^+)

pH = -log(3.2 x 10^-3)
Punch in 3.2 x 10^-3 on the calculator. Hit the log key and you will get -2.59 so
pH = -(-2.49) = +2.49.