Titrations - Controlled addition and measurement of the amount of a solution of known concentration that is required to react with a measured amount of a solution of unknown concentration.

Important Terms and Concepts Standard solution – solution of known concentration. Indicators – weak acid or weak base dyes that are sensitive to pH (hydronium ion concentration). Equivalence point – The point at which the two solutions used in a titration are present in chemically equivalent amounts. For our purposes, H3O+ = OH- (moles of Acid = moles of Base)

Review How many moles of cesium hydroxide are needed to react with excess magnesium phosphide to form 35.8 grams of cesium phosphide? ___ CsOH + ___ Mg3P2 → ___ Mg(OH)2 + ___ Cs3P

Review Calculate the molarity of a solution prepared by dissolving 5.64 grams of (NH4)2SO4 in enough water to produce 80.0mL of solution. What volume of 1.6 M nitric acid solution can be made with 66.0 grams of HNO3?

Neutralization Main Idea: Acids react with bases to produce a salt and water. http://www.brooklyn.cuny.edu/bc/ahp/SDKC/Chem/SD_AcidBase.html

Predicting Products Example #1: phosphoric acid (H3PO4) reacts with magnesium hydroxide Mg(OH)2. H3PO4 + Mg(OH)2 → Example #2: sulfuric acid reacts with lithium hydroxide

Practice Titration Problems 2 HCl + Ba(OH)2  BaCl2 + 2 H2O 1) It requires 27.4mL of a standard solution of 0.0154M Ba(OH)2 to completely neutralize 20.0mL of an HCl solution. Find the molarity of the acid. Known Solution Unknown Solution Start bridge with volume of known solution.

Practice Titration Problems 2 KOH + H2SO4  K2SO4 + 2 H2O 2) What volume of 1.25M potassium hydroxide is required to neutralize 25.0mL of 12.0M sulfuric acid? Known Solution Unknown Solution Start bridge with volume of known solution.

Practice Titration Problems H2SO4 + 2 LiOH  Li2SO4 + 2 H2O 3) 17.6mL of H2SO4 is neutralized by 30.6 mL of 0.0165M LiOH solution. Find the molarity of the acid. Known Solution Unknown Solution Start bridge with volume of known solution.

Practice Titration Problems 1) It requires 27.4mL of a standard solution of 0.0154M Ba(OH)2 to completely neutralize 20.0mL of an HCl solution. Find the molarity of the acid. Since we are switching substances: STOICHIOMETRY!!!! mol HCl LAcid ? 27.4mL Base = 0.0274L Base Mole-to-mole using balanced equation! 0.0154mol Ba(OH)2 LBase 2 HCl + Ba(OH)2  BaCl2 + 2 H2O Start bridge with volume of known solution. 20.0mL Acid = 0.0200L Acid 0.0274L Base 0.0154 mol Ba(OH)2 2 mol HCl  1 LBase 1 mol Ba(OH)2 0.0200LAcid = 0.0422M HCl

Practice Titration Problems 2) What volume of 1.25M potassium hydroxide is required to neutralize 25.0mL of 12.0M sulfuric acid? 12.0 mol H2SO4 L Known Solution 25.0mL = 0.0250L 0.600mol 1.25 = Unknown Solution 1.25 M KOH X Mole-to-mole using balanced equation! 2 KOH + H2SO4  K2SO4 + 2 H2O 0.0250L H2SO4 12.0 mol H2SO4 2 mol KOH 1 L 1 mol H2SO4 = 0.480 L or 480. mL KOH Start bridge with volume of known solution.

Practice Titration Problems 3) 17.6mL of H2SO4 is neutralized by 30.6 mL of 0.0165M LiOH solution. Find the molarity of the acid. 30.6 mL LiOH = 0.0306 L LiOH Known Solution 0.0165 mol LiOH L 0.000252 mol Unknown Solution 17.6 mL H2SO4 = 0.0176L H2SO4 0.0176L H2SO4 + 2 LiOH  Li2SO4 + 2 H2O Mole-to-mole using balanced equation! 0.0143 M H2SO4 0.0306 L LiOH 0.0165 mol LiOH 1 mol H2SO4 2 mol LiOH 1 L Start bridge with volume of known solution.