Titration with multi-protic acids and multi-hydroxy bases Spring 2008

Neutralization means equal amounts of H+ ions are balanced by OH- ions Mononprotic acids have 1 H+ Monohydroxy bases have 1 OH- The actual molarity of these acids or bases is equal to the Molarity of the solution on the label. [multiply the strength x the number of ions in the formula] 2 M HCl has 2 Moles/L x 1 H+ = 2Moles H+ ions 5 M HF has 5 Moles/L x 1 H+ = 5 Moles H+ ions

Diprotic Acids and Dihdyroxy Bases Di- means 2 H2SO4 is a diprotic acid Ba(OH)2 is a dihydroxy base The strength of these solutions is greater than a monoprotic or monohydroxy substance 2M H2SO4 really is like a 4Molar solution 2 Moles/Liter x 2 H+ = 4 Moles of H+ ions 3M Ca(OH)2 is really like a 6 Molar solution 3 Moles/Liter x 2 OH- = 6 Moles of OH- ions

Triprotic Acids and Trihdyroxy Bases Tri- means _____ ___________is a triprotic acid __________ is a trihydroxy base The strength of these solutions is greater than a monoprotic or monohydroxy substance 2M H3PO4 really is like a _____Molar solution 2 Moles/Liter x ____ H+ = ___ Moles of H+ ions 3M ____(OH)3 is really like a ____Molar solution 3 Moles/Liter x ____ OH- = ____ Moles of OH- ions

Solving Tricky Titration Problems Remember to multiply the number of H or OH ions in the acid or base formula by the strength of the solution Example: 20 ml of 2.0 M H2SO4 are needed to neutralize what volume of a 1M NaOH solution? Ma = 2.0Moles/L x 2 H+ ions = 4.0 Moles H+ ions Va= 20ml Mb = 1Mole/L x 1 OH- ion = 1 mole OH- ions Ma x Va = Mb x Vb (4 moles H+) ( 20 ml) = (1 mole OH-) ( Vb) 80 ml = Vb

50 ml of 2 M H3 PO4 is neutralized by how much of 2M Ca(OH)2? 2M x 3 H+ = 6 M H+ = Ma 2M x 2 OH- = 4M OH- = Mb Ma x Va = Mb x Vb ___________________________ ____________________________ Read carefully and check your answer. What is the name of the salt produced? What is its formula? What is the pH of the solution produced?

Review Material: Fill in with words, phrases, number phrases,etc. If [H+] > [OH-] the pH is _____________ and the solution is __________. If [H+] < [OH-] the pH is _____________ and the solution is __________. If [H+] = [OH-] the pH is _____________ and the solution is __________. pH of 3 means the [H+] =____________ and the [OH-] is _____________. pH of 12 means the [H+] =____________ and the [OH-] is _____________.