Buffers in Household Products—Advanced Inquiry Laboratory Kit

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Big Idea 6, Investigation 15, Primary Learning Objective 6.20 Every living cell contains natural buffer systems to maintain the constant pH needed for proper cell function. Consumer products are also often buffered to safeguard their activity. Students discover the wide range of buffering action in common household products using this advanced inquiry lab activity. Many household products contain buffering chemicals such as citric acid, sodium carbonate, sodium benzoate, and phosphates or phosphoric acid. The lab begins with an introductory activity to identify the buffering regions in the neutralization of a polyprotic weak acid. The results provide a model for guided-inquiry design of a procedure to determine the buffering agents in eight different household products, including foods and beverages and over-the-counter drugs. Procedures may include creating titration curves, calculating pKa values, and analyzing the buffer capacity and composition. Students may recommend additional consumer products for further inquiry study. Complete for 24 students working in pairs. Common laboratory equipment is required and available separately.