pH Pipes

Indicators are chemicals that show what type of chemical reaction occurred. I decided to have some fun with some pH indicators--chemicals that signify if a solution is acidic or basic. In the video, 3 different pH indicators, bromothymol blue, phenol red, and phenolphthalein (and ammonia) are used. The solutions are in long plastic pipes whereupon Alka Seltzer tablets are dropped. The Alka Seltzer tablets react with the water to produce carbon dioxide gas. The carbon dioxide dissolves in water creating carbonic acid and thus making the solution more acidic. The color of the solution changes as a result. Later ammonia, a base, is added to show how the color changes when the solution turns basic.

Sodium Acetate Crystallization

Crystals are solids that are formed from regular repeating patterns of molecules. One of the most spectacular crystal formations is sodium acetate. I made sodium acetate by using a procedure from instructables. It was interesting, but very time consuming, so purchasing a bottle of it maybe a better way to go. When sodium acetate, CH₃–COO^– Na⁺, is dissolved in a little water, the oppositely charged ions dissociate. If left undisturbed and cooled, the ions do not form crystals and the sodium acetate remains a liquid, far below its melting point. If disturbed, or a tiny sodium acetate crystal is introduced into the solution, the oppositely charged ions (CH₃–COO^– and Na⁺) form a solid crytal structure quickly. The process is exothermic, releasing heat energy, which explains why this process is commonly referred to as "hot ice".