2 Acid-Base ReactionsIf we mix a strong acid solution with a strong base solutionwe get a neutral solution that is neither acidic nor basic.For example:HCl + NaOH → NaCl + H2OH2SO4 + 2 KOH → K2SO4 + 2 H2O
3 Acid-Base Reactions Mixing a strong acid with a strong base gives us watera saltthe conjugate base of the acid plus the conjugate acid of the baseIn this case, a salt is an ionic compound of any kind.
4 Acid-Base ReactionsIn most cases, the net ionic equation of a neutralization reaction is:H3O+ + OH- → 2 H2OThe salt that is formed usually stays in solution.The salt ions are spectator ions.
6 TitrationThe point where the number of mols of hydronium ions equals the number of mols of hydroxide ions is called the equivalence point.The stoichiometric ratio of the acid to the base in the balanced equation tells us where the equivalence point is.
7 TitrationExample 1:How many mols of sulfuric acid are required to neutralize 0.50 mols of sodium hydroxide?nNaOH = 0.50 molH2SO4 + 2 NaOH → Na2SO4 + 2 H2OnNaOHnH2SO4211×nNaOH20.50 mol2=➙nH2SO4==nH2SO4=0.25 mol
8 TitrationA titration is a neutralization reaction under controlled conditions.We control the amounts of acid and base reacted while monitoring the pH of the reaction solution.When we reach neutralization (the equivalence point), we carefully measure the amounts of the acid and the base.
9 Titration A titration uses a flask or beaker to hold the unknown solutiona burette to hold the known (standardized) solutionan indicator (added to the flask) to show the end of the titration.
10 Titration The burette shows the volume of titrant added to the flask. We read the meniscus to find the amount added.Placing a white sheet with a black section below the meniscus can help to define the meniscus.
11 TitrationWe can use an indicator to show the equivalence point (end point) of the titration.We can also use a pH meter to find the end point by generating a pH curve.
12 Titration On the left, a strong base is added to a strong acid. The equivalence point occurs at pH = 7.
13 Titration On the right, a strong acid is added to a strong base. The equivalence point also occurs at pH = 7.
14 Titration nNaOH nNaOH nH2SO4 Example 2: A 25-mL solution of H2SO4 is completely neutralized by 18 mL of 1.0 M NaOH. What is the concentration of the H2SO4 solution?MNaOH = 1.0 M VNaOH = 18 mL = LMH2SO4 = ? M VH2SO4 = 25 mL = LH2SO4 + 2 NaOH → Na2SO4 + 2 H2OnNaOH=MNaOHVNaOH=(1.0)(0.018) mol=0.018 molnNaOHnH2SO421nNaOH20.018 mol2=➙nH2SO4===molnH2SO4VH2SO4mol0.025 LMH2SO4===0.36 M