#[H+] concentration

For HA H+ + A- , if Ka = 1.0 × 10⁻⁵ and [HA] = 0.05 M at equilibrium, what is [H+] ?

Ka = ([H+][A-]/[HA]) = (x²/0.05 - x) ≈ (x²/0.05) = 1.0 × 10⁻⁵ , x² = 5.0 × 10⁻⁷ , x = 7.07 × 10⁻⁴ M .

Ref: NCERT Class 11 Chemistry > Chapter 6: Equilibrium > Topic: Homogeneous and Heterogeneous Equilibria and Applications of Equilibrium Constant