Acid-Base Titrations

Recommended for grades 9–16.

Figure from experiment 17 from Investigating Chemistry through Inquiry

Introduction

A titration is a process used to determine the volume of a solution needed to react with a given amount of another substance. When titrating a solution of the strong acid hydrochloric acid, HCl, with a solution of the strong base sodium hydroxide, NaOH, the hydrogen ions from the HCl react with hydroxide ions from the NaOH in a one-to-one ratio to produce water in the overall reaction:

${{\text{H}}^{\text{ + }}}{\text{(aq) + C}}{{\text{l}}^ - }{\text{(aq) + N}}{{\text{a}}^{\text{ + }}}{\text{(aq) + O}}{{\text{H}}^ - }{\text{(aq)}} \to {{\text{H}}_{\text{2}}}{\text{O(l) + N}}{{\text{a}}^{\text{ + }}}{\text{(aq) + C}}{{\text{l}}^ - }{\text{(aq)}}$

When an HCl solution is titrated with an NaOH solution, the pH of the acidic solution is initially low. As base is added, the change in pH is quite gradual until close to the equivalence point, when equimolar amounts of acid and base have been mixed. Near the equivalence point, the pH increases very rapidly. The change in pH then becomes more gradual again, before leveling off with the addition of excess base.

Objectives

In the Preliminary Activity, you will titrate a solution of the strong acid hydrochloric acid, HCl, with a solution of the strong base sodium hydroxide, NaOH. The concentration of the NaOH solution is given and you will determine the unknown concentration of the HCl.

After completing the Preliminary Activity, you will first use reference sources to find out more about acids, bases, and acid-base titrations before you choose and investigate a researchable question utilizing acid-base titrations.

Sensors and Equipment

This investigation requires each of the following Vernier sensors and equipment (unless otherwise noted):

pH Sensor

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Download Experiment Preview

The student-version preview includes:

Step-by-step instructions for the Preliminary Activity
List of materials and equipment

Note: The experiment preview of the Preliminary Activity does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.

Download Preview

Standards Correlations

Choose a standard to view standards correlations for this experiment.

See all standards correlations for Investigating Chemistry through Inquiry »