Validation of analytical methods is a fundamental subject for chemical analysts working in chemical industries. These methods are also relevant for pharmaceutical enterprises, biotechnology firms, analytical service laboratories, government departments, and regulatory agencies. Therefore, for undergraduate students enrolled in majors in the field of chemistry, learning validation of methods and chemometrics is essential. The following article presents the development of a laboratory experiment to validate a method to determine CO[subscript 2] by means of potentiometry. This experiment will allow students to approach a subject that may be part of their professional activities. The validated method was applied to determine CO[subscript 2] in commercial carbonated beverages. A teaching activity on method validation was proposed and implemented for senior students. After its application, students were able to improve significantly their knowledge on the topic. The potentiometric technique, underlying the validated method, has the advantage of being easy to apply and accessible in almost any undergraduate laboratory. Furthermore, the required reagents are available practically in any chemistry department. The shown procedures might be executed as laboratory activities in analytical chemistry due to their overall simplicity and rapidity.