4.6 Introduction to Titration

An analytical lab technique where a known volume and molarity of a titrant is dispensed from a buret into a flask containing a measured quantity of the analyte

Titration

Can you determine the moles of titrant at equivalent point without doing the titration itself?

Yes

How to determine the moles of titrant at equivalent point without doing the titration itself?

By using the balanced chemical equation specific to the reaction

The equivalence point is when:

The moles of the titrant and moles of analyte are stoichiometrically equivalent

What does moles of titrant and moles of analyte being stoichiometrically equivalent mean?

The two react in a ratio determined by the balanced equation

How to know when the equivalence point is reached?

By using a color change to signal the end point

Three types of common titrations:

Acid-base, redox, and precipitation

What is the titrant in acid-base titrations?

Acid or base

How to determine the end point of a strong acid/base reaction?

By adding an acid-base indicator or by using pH meters

When does an acid-base indicator added to a strong acid/base reaction change color?

At a pH close to 7

When is a color change produced in redox reactions?

When the oxidation state of a metal ion in the reaction changes

What reacts with what in precipitation reactions?

A titrant with ions in the analyte

What happens when the titrant reacts with ions in the analyte?

A precipitation can occur

What signals the endpoint in precipitation titrations?

The formation of a precipitate or its color change

Equipment needed to perform a titration include:

Buret, volumetric pipet or lab balance, Erlenmeyer flask, acid/base indicator or pH meter

What is buret used for in titration?

Keeping track of titrant volumes

What is volumetric pipet used for in titration?

Dispensing a specific volume of the analyte solution

What is lab balance used for in titration?

To mass a sample

Diagram of titration setup equipment:

The data needed to be recorded when performing titration include:

Molarity of titrant, initial volume of titrant, final volume of titrant, volume or mass of analyte

If a pH meter is used to monitor an acid/base titration, it’s common to do what?

Plot pH and volume of titrant on a graph

How to determine amount of titrant needed to react fully with analyte from a titration curve?

By dropping a vertical line down at the equivalence point