All acid/buffer equations

• For weak acids Ka =

  [H+]^2 /[HA]
• Ka =

  [A-] [H+] / [HA]
• pH =

  -log[H+]
• [H+] =

  10^-pH
• Kw =

  [H+] X [OH-]
• Kw =

  1.00 x 10-14 mol^2 dm-6
• Calculating for buffers

  When the concentrations of [HA] and [A-] are the same:

  • Ka = [H+] [A-]/[HA] but if [A-] and [HA] are the same then they cancel so Ka = [H+]
  • And pKa = pH
• Calculating [H+] for buffers

  [H+] = Ka x [acid]/[salt]
• Buffer calculations of ratio of acid to conjugate base

  [base]/[acid] = Ka/[H+]