pH from K_a calculator
Weak-acid pH from K_a and analytical concentration (common approximations).
Calculator
How to use
pH from K_a
Typical first pass: $[H^+] \approx \sqrt{K_a C}$ when dissociation is small.
Validate assumptions (C ≫ [H⁺], etc.) for your problem.
Educational use only. Double-check values for labs, homework, and exams.