Concept/Skills Development

Demonstration 7: Silent Demo--Reactivity and Concentration

As the concentration of an acid decreases, reactivity with metals decreases also.

Suggestions for Other Demonstrations

Natural Indicators - Extractions of colored dyes from plants that can function as acid-base indicators. [Sk v3 50; Sq CF 27; Bo CA 92]

Properties of Acids and Bases - Demonstrates classical properties of acids and bases. [Sk v3 58; Su v2 171]

pH of Familiar Products - pH measurement of household chemicals using indicator solutions or a pH meter reveals that many substances are acids and bases. [Sk v3 65; Bo CA 133]

Disappearing Ink - A blue "ink" spot on white cloth is caused to fade and disappear. [Su v2 174; Sq CF 325]

Invisible Painting - A pattern is painted on a sheet of paper with phenolphthalein (colorless) and the pattern is developed when the paper is sprayed with sodium hydroxide solution. [Sk v3 47]

Cylinders of Color - Create color changes in solutions containing several different acid-base indicators. [Sk v3 114 (uses Dry Ice); Sq CF 127 (uses Alka Seltzer(TM)), Su v1 38]

Acid-Base Nature of Common Gases - The properties of several gases are revealed: carbon dioxide in breath [Bo CA 15], sulfur dioxide [Su v2 165]; and ammonia [Sq CF 59].

Sealed-Bag Reactions with Acids and Bases - A reaction occurs among three substances mixed in a sealed-plastic bag [Sq CF 345] or between two substances in a sealed-plastic bag [Sk v3 100].

Acid Base Titration/Conductivity - Conductiometric titrations of barium hydroxide and sulfuric acid. [Sk v3 152]

Making Hydrogen Gas from an Acid and a Base - Hydrogen gas is collected in a balloon attached to each of two flasks. One flask contains aluminum foil and hydrochloric acid; the other, aluminum foil and sodium hydroxide. [Su, v2, 33]

Acid-Base Indicators: A Voice-Activated Chemical Reaction - Allow students to speak into a flask containing bromthymol indicator. After several tries, the solution will turn yellow. [Su, v1 40]

Miscellaneous Applications - Measuring acid rain [Su CA 191], measuring soil pH [Bo CA 194], what's in baking powder [Bo CA 223], carbonates in rocks, minerals, and eggshells [Bo CA 17; Sq CF 305].

Acids and Bases
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