Acid Dissociation Constant, Ka > Experiment #27 from Chemistry with Vernier

Figure from experiment 27 from Chemistry with Vernier

Introduction

Acetic Acid, HC₂H₃O₂, is a weak acid that dissociates according to this equation:

${\text{H}}{{\text{C}}_{\text{2}}}{{\text{H}}_{\text{3}}}{{\text{O}}_{\text{2}}}{\text{(aq)}} \to {{\text{H}}^{\text{ + }}}{\text{(aq) + }}{{\text{C}}_{\text{2}}}{{\text{H}}_{\text{3}}}{{\text{O}}_{\text{2}}}^{\text{ - }}{\text{(aq)}}$

In this experiment, you will experimentally determine the dissociation constant, K_a, for acetic acid, starting with solutions of different initial concentrations.

Objectives

In this experiment, you will

Gain experience mixing solutions of specified concentration.
Experimentally determine the dissociation constant, K_a, of an acid.
Investigate the effect of initial solution concentration on the equilibrium constant.

Sensors and Equipment

This experiment 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?

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The student-version preview includes:

Step-by-step instructions for computer-based data collection
List of materials and equipment

Note: The experiment preview of the computer edition 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.

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Acid Dissociation Constant, Ka