Two Gas- in - a bag reactions to show the predictive power of the relative acid- base strength chart. 6

ABSTRACT : High-school chemistry curricula have often been maligned for being too long on theoryand too short on applied chemistry. Certainly, very little consideration is given in most curricula to the rich arena of descriptive chemistry, particularly helping students develop the skills of being able to predict products of chemical reactions and of using resource tables to reason which products are most likely to form. This article describes a relatively simple demonstration in which two different pairs of solid chemicals are mixed in two different Ziploc bags in the presence of a small quantities of water. In both cases, the chemicals react to produce gases that are trapped in and fill up the bags. Students are informed that the reactions producing those gases are Brønstedâ€Lowry acidâ€base type reactions. Given that all four chemicals have the potential to be amphoteric, students must determine which member in each pair will act as the acid and which as the base. Making this determinationâ€and therefore the determination of the productsâ€requires students to apply an understanding of the Relative Acidâ€Base Strength chart. 56

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