Dry Ice and Indicators

Effervescent powder contains a mixture of tartaric acid and Bullrich salty substances which, although related, combine under normal conditions only slowly, but if one introduces water into the mix they rush into each others arms with a triumphant effervescence. 

Four 800-mL beakers, glass rods, two 5-mL measuring cylinders, safety glasses, protective gloves. 

Phenolphthalein, methyl red, phenol red, Yamada s universal indicator (see solution 4 below), NaOH, dry ice, distilled water. 

005 g of thymol blue, 0.012 g of methyl red, 0.06 g of bromothymol blue and 0.10 g of phenolphthalein are dissolved in 100 mL ethanol. 0.01 mol/L NaOH is added until the solution is green, and the solution is finally diluted to 200 mL with H2O this is Yamada s universal indicator. 

Each beaker contains 600 mL of distilled water. Five mL of one of the above indicator solutions are added to the beakers, followed by 5 mL of 0.1 mol/L sodium hydroxide. Pieces of dry ice, about the size of a walnut, are now added to the colored alkaline solutions. A reaction at once occurs, the liquids appear to boil, and the colors change as follows  

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