Mobile App to Quantify pH Strips and Monitor Titrations: Smartphone-Aided Chemical Education and Classroom Demonstrations

pH determination and acid–base titrations are essential experiments performed by high school and university undergraduate students alike throughout their chemistry education. While these experiments often rely on conventional pH meters for quantification and pH test strips or indicators for qualitative assessments, we demonstrated herein that a smartphone-based pH determination technique, performing digital image analysis, particularly the determination of either the dominant wavelength or the RGB intensities, could readily replace all but one conventional pH meter in a classroom setting. Using an in-house developed smartphone-based pH reading application (app), students were able to determine the pH and perform titrations using pH strips and universal indicators, producing results matching those determined with a standard pH meter. The app and its “variants” are available for download (https://tinyurl.com/2dashjyk and https://tinyurl.com/4d73wnxt), and no prior knowledge of coding or programing was required from the students. All that was needed was an Android 11 phone or tablet with an Internet connection. Moreover, the students and instructors’ reactions to the mobile app alike were very positive and showcased the need and interest for such inexpensive technology, which allows for the running of an entire class for pH determination of multiple real-life samples or acid/base titration without using standard pH meters.