Validation of the use of low-cost pH meters in acid/base titrations

Abstract

The study of complex chemical concepts is often limited to the use of simple and specialised instrumentation, that is commonly found in all laboratories, although at a relatively high price. However, in recent years, technological advances and globalisation have made possible the emergence of low-cost instruments (balances, thermometers, manometers, pH meters, etc.) that, despite their low accuracy, can be very useful for detecting significant changes in a magnitude and, therefore, they can be used for didactic experiences outside traditional laboratories. This work focuses on the validation of a low-cost non-professional pH meter, used in swimming pools and fish tanks, for use them as potentiometric detector in acid-base titrations. Their use has been validated in strong acid/strong base and weak acid/strong base titrations, obtaining only a 1% error respecting to the theoretical curve in both cases. Thus, these pH-meters have been used to determine the ammonia content of a household cleaner after titration with hydrochloric acid, obtaining excellent results.