Acids and bases equations

• pH = -log10 [H+]

  Calculate the concentration of HCL if its concentration is 0.015 moldm-3

  pH = -log10(0.015) = 1.82

  Calculate the pH of HCL with a concentration of 4.42X10^-8

  pH = -log10[4.42X10^-8] = 7.35
• [H+] = 10^-pH

  Calculate the [H+] of HCL with pH of 3.2

  [H+] = 10^-3.2 = 6.3X10^-4

  Calculate the [H+] of HCL with pH of 5.6

  [H+] = 10^-5.6 = 2.5X10^-6
• Ka = $\frac{\left[H^+\right]\left[A^-\right]}{\left[HA\right]}$


  a solution of acid [HA] = 0.1 has [H+] = 7.94X10^-6

  Ka = $\frac{\left[7.94\times10^{-6}\right]\left[7.94\times10^{-6}\right]}{\left[1-7.94\times10^{-6}\right]}$= 6.3X10^-10
• pKa = -log Ka

  Calculate the pKa of an acid with Ka of 4.21X10^-4

  pKa = -log 4.21X10^4 = 3.36

  Calculate the pKa of an acid with Ka of 6.1X10^-3

  pKa = -log 6.1X10^-3
• Ka = 10^-pKa

  Calculate the Ka of acid with pKa of 4.5X10-5

  Ka = 10^-4.5X10^-5 = 1.00
• [H+] = $\sqrt{Ka\ \times\left[HA\right]}$


  Calculate the pH of 0.375moldm-3 nitrous acid with a Ka of 4.43 X10^-4

  [H+] = $\sqrt{4.43\times10^{-4}\times0.375}$ = 0.0129

  pH = -log10[H+]

  pH = -log10 0.0129 = 1.89