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

pH determination and acid-base titrations areessentialexperiments performed by high school and university undergraduatestudents alike throughout their chemistry education. While these experimentsoften rely on conventional pH meters for quantification and pH teststrips or indicators for qualitative assessments, we demonstratedherein that a smartphone-based pH determination technique, performingdigital image analysis, particularly the determination of either thedominant wavelength or the RGB intensities, could readily replaceall but one conventional pH meter in a classroom setting. Using anin-house developed smartphone-based pH reading application (app),students were able to determine the pH and perform titrations usingpH strips and universal indicators, producing results matching thosedetermined 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 fromthe students. All that was needed was an Android 11 phone or tabletwith an Internet connection. Moreover, the students and instructors'reactions to the mobile app alike were very positive and showcasedthe need and interest for such inexpensive technology, which allowsfor the running of an entire class for pH determination of multiplereal-life samples or acid/base titration without using standard pHmeters.