In this video I first add 10 mL of 1 M, NH4OH to a graduated cylinder, and then mix it with 2 mL of phenolphthalein (an indictor that stays colorless below pH 8 and becomes red above pH 10). Now you will see the color of the solution is red due to the basic nature of the 1 M NH4OH. Then I add dry ice into the cylinder. You will see CO2 bubbles formed in the cylinder. After a while, the color of the solution changes from red to pink to colorless. This is because some of CO2 dissolves into the NH4OH solution, neutralizing the basic solution due to the acidic nature of dissolved CO2, as a form of carboxylic acid for example. As a result, the phenolphthalein changes its red color to pink and finally to colorless in response to the pH decrease in the solution. By Dr. Hanbin Mao for Gen Chem II 10061 @ KSU, fall 2009. Video taped by Soma Dhakal.
Just having fun with a pipette and a graduated cylinder! #YOLO Song - How We Do by 50 Cent & The Game
Video Rating: 5 / 5
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