Titration Chemistry Basics

Titration Lab technique commonly utilized to determine an UNKNOWN concentration of a chemical compound with a KNOWN concentration of another chemical compound. Lab technique commonly utilized to determine an UNKNOWN concentration of a chemical compound with a KNOWN concentration of another chemical compound. Chemical compounds combine with exact stoichiometric proportions Chemical compounds combine with exact stoichiometric proportions Analyte— Analyte— Chemical compound with UNKNOWN concentration Chemical compound with UNKNOWN concentration Titrant— Titrant— Chemical compound with KNOWN concentration Chemical compound with KNOWN concentration Measured with volume and concentration Measured with volume and concentration Added to chemical compound with unknown concentration in titration Added to chemical compound with unknown concentration in titration

1) Acid-Base Titration Most common type of titration Most common type of titration Reactants: acid, base Reactants: acid, base Buret contains titrant and the analyte in solution is contained in a flask Buret contains titrant and the analyte in solution is contained in a flask Indicator— Indicator— Added to analyte to indicate a color change at the equivalence point of a titration Added to analyte to indicate a color change at the equivalence point of a titration

Titration Terminology End Point : End Point : point in a titration where a color change is observed due to indicator. point in a titration where a color change is observed due to indicator. Equivalence Point : Equivalence Point : point during a titration when neutralization has occurred. point during a titration when neutralization has occurred. Titrant has neutralized analyte Titrant has neutralized analyte Cannot usually be observed Cannot usually be observed We can plot a titration on a graph— titration curve We can plot a titration on a graph— titration curve **Ideally, equivalence point = endpoint **

Example 1: Shrek wants to know the concentration of a solution of calcium hydroxide the fairy godmother gave him. He conducts an acid- base titration and finds ml of M HNO 3 neutralizes 10.0 ml of the calcium hydroxide solution. What is the concentration of the calcium hydroxide solution?

Example 2: You are a research assistant in a NC State Lab and need to neutralize ml of M HCl using M NaOH. What volume of NaOH solution will you need to complete this task?

2) Redox Titrations Involves the oxidation-reduction of 2 chemical compounds Involves the oxidation-reduction of 2 chemical compounds One compound reduced ( titrant ) One compound reduced ( titrant ) One compound oxidized ( analyte ) One compound oxidized ( analyte ) Most common titrant—potassium permanganate (KMnO 4 ) Most common titrant—potassium permanganate (KMnO 4 ) MnO 4 - ion oxidizes other ions MnO 4 - ion oxidizes other ions Does not require a separate indicator Does not require a separate indicator Oxidizes metal cations, used to determine the % or amount of a particular metal in a compound Oxidizes metal cations, used to determine the % or amount of a particular metal in a compound

Example 1: A mining company obtains a g sample of iron ore. This ore is dissolved in an acidic solution and the iron completely dissociates from the ore into Fe +2 ions. This solution is titrated with ml of M KMnO 4 (aq). What is the percentage of iron in the iron ore sample?

Homework Read over lab procedure ----Thursday Read over lab procedure ----Thursday pp #75, 79, 83, 89, 91 (due Friday) pp #75, 79, 83, 89, 91 (due Friday)