At-Home Titration: Magnesium Hydroxide in Milk of Magnesia Using an Inexpensive Digital Balance and Natural Food Dye as Indicators

A quantitative titration of the amount of magnesium hydroxide in milk of magnesia using only items purchased in grocery and retail stores is reported. Either vinegar or a solution of food grade citric acid serves as the titrant, while food dyes advertised as being extracted from natural sources provide the end-point indicator. An inexpensive, digital kitchen balance with 0.01 g resolution allows for quantitation of the amount of titrant added. Students who performed this experiment either in class or remotely generally determined amounts of magnesium hydroxide in milk of magnesia that were within 10% of that claimed by the manufacturer. That easily obtained materials are used in this activity makes it amenable for experimentation in remote settings. The use of both the natural food dyes and inexpensive digital balance opens a wide swath of possibilities for new experiments to be developed for at-home experimentation.