Is this Solution Pink Enough? A Smartphone Tutor to Resolve the Eternal Question in Phenolphthalein-Based Titration

“Is this solution pink enough?” is a persistent question when it comes to phenolphthalein-based titration experiments, one that budding, novice scientists often ask their instructors. Lab instructors usually answer the inquiry with remarks like, “Looks like you have overshot the end point”, “Perhaps you should check the amount of the indicator and redo”, and “The pink can be fainter.” However, in a large classroom setting, it often becomes tedious for teachers to provide personalized remarks to students on their titration conduct at frequent intervals. In an effort to get the learners to become independent in evaluating their titration experiments, in this paper, the design, development, and implementation of a new smartphone tutor application named Titration ColorDarts (TCD) has been presented. TCD uses the camera function to analyze the pink color of the titration solution to provide learners with a feedback report on their experimental conduct. TCD maps the gradient of pink (from light to dark) to a corresponding performance score (on a scale of 1 to 10) and presents it in a gamified manner on a dartboard. It generates a report that includes question prompts and hints to elicit a learner’s reasoning for independently identifying potential sources of error in their experiment and for figuring out how they can be resolved. The results from the initial pilot exercise conducted with undergraduate students corroborate the effectiveness of TCD as a lab tutor.