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.

Chemical compounds combine with exact stoichiometric proportions

Analyte— Chemical compound with UNKNOWN concentration

Titrant— Chemical compound with KNOWN concentration Measured with volume and concentration Added to chemical compound with unknown concentration

in titration

1) Acid-Base Titration

Most common type of titration

Reactants: acid, base

Buret contains titrant and the analyte in solution is contained in a flask

Indicator— Added to analyte to indicate a color change at

the equivalence point of a titration

Titration Terminology

End Point: point in a titration where a color change is observed

due to indicator.

Equivalence Point: point during a titration when neutralization has

occurred. Titrant has neutralized analyte Cannot usually be observed

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 23.30 ml of 0.0200 M HNO3 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 20.00 ml of 0.1030 M HCl using 0.2010 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 One compound reduced (titrant) One compound oxidized (analyte)

Most common titrant—potassium permanganate (KMnO4)

MnO4- ion oxidizes other ions

Does not require a separate indicator Oxidizes metal cations, used to determine the %

or amount of a particular metal in a compound

Example 1:

A mining company obtains a 0.2865 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 26.45 ml of 0.02250 M KMnO4 (aq). What is the percentage of iron in the iron ore sample?

Homework

Read over lab procedure ----Thursday

pp. 163-164 #75, 79, 83, 89, 91 (due Friday)