Cabbage Juice Lab
Purpose: To test the acidity and basicity of common household products using a premade cabbage juice indicator.
Introduction Acids and bases are chemicals commonly used in the lab, and, even though we may not realize it, they are also found in substances we use at home on a daily basis. To test the acidity or basicity of a substance, we can titrate each until the endpoint is reached, or use an indicator. Something as simple as litmus paper can be used, whereby blue litmus paper will turn red in the presence of an acid, and bases will turn red litmus blue. We can also use universal indicator and bromothymol blue, but in this lab, we are going to be using cabbage juice. Cabbage juice indicator is made by grinding up red cabbage to obtain the dye. When added to an acid, it will turn a light red to pink hue, while bases will turn blue, green, and even yellow. Thus, in this lab you will test ten substances for their acidity or basic content using a cabbage juice indicator. Hypothesis Make an educated guess as to which substances are acids and which are bases. Associate a pH with the acid or base. Prelab Questions
1. The pH scale ranges from _________ to _________ . 2. Acids are _________ seven and bases are _________ seven. 3. Neutral substances have a pH of _________. 4. Strong acids and bases will __________________ ionize, while weak acids and bases only __________________ ionize. 5. Identify each as strong or weak acids and bases. a. pH = 1 b. pH = 13 c. pH = 5
d. [H+] = 1.0 x 10-5 M e. [OH-] = 1.0 x 10-3 M
Materials Beakers Household acids & bases Hydrochloric Acid
Sodium Hydroxide Pipette Well Plate
Diagram of Apparatus You need to draw a before and after picture to indicate the color change AND label each well with the substance name and whether it is an acid, base, or neutral. BEFORE AFTER
1. Obtain all ten substances and fill your well plates HALF-full with the provided pipette. (MAKE SURE YOU LABEL...
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