Question

What is the pH of a solution with [H3O+] = 1 × 10-9 M? Chemistry is so lame and useless for 99% of the population

Answer 1

The definition of p^H = -log[H⁺] or -log[H₃O⁺]

where H⁺ -> Hydrogen ion and H₃O⁺ ->Hydronium ion.

The square brackets means concentration of the enclosed ion.

M means Molarity which is an useful and intelligent expression for mol/lt. This is just like we express x% as x in 100 parts. Eg. 99 in 100 parts = 99%

I assume we learnt log function in High School and calculate the result purely mathematically as:

p^H = -log[H₃O⁺] = -log (1*10^-9) = -log1 - log10^-9 = 0 +9 = 9