Acid/base indicators observation skills self-directed lab

Phenolphthalein will produce a reddish color in a basic environment and be neutralized back to colorless if added to sufficient acid.

4 small clear cups or beakers
"Magic Bottle" filled with solution of 3 sodium hydroxide pellets to 1000 ml distilled water
Phenolphthalein
12M Hydrochloric acid

Safety Precautions
Wear protective gloves, chemical-resistan apron and safety goggles and always follow laboratory safety rules while performing demonstrations.

Preparation
Prepare "Magic Bottle" with 3 NaOH pellets in 1 liter of distilled water. Setup cups ahead of time as follows:
Cup #1à 1-3 drops phenolphthalein solution
Cup #2à Nothing
Cup #3à 1-3 drops phenolphthalein solution
Cup #4à 3-5 drops 12M HCl

Explain that the "magical" bottle can pour "wine" if poured out using the left hand (pour a little into Cup#1 producing red color), it will pour "water" if poured using the right hand (pour some into Cup#2 producing no color). Now try the left hand for "wine" into Cup #3 and the right hand for "water" for Cup #4. Continue explaining some people might find the "wine" in Cup #1 too strong so it can be diluted (pour Cup#1 into Cup # 2). If it is too weak it can be made stronger by pouring the contents of Cup #3 into it (do this). However maybe it's not such a good idea working with "wine" in an academic environment so change it all back into "water" by pouring the combined reddish chemicals into Cup #4 to neutralize the bases.

This demonstration can then be continued as a student self-directed lab by having plastic pipettes containing water, phenolphthalein solution, and hydrochloric acid (give students 6M HCl not 12M). Students are to explain what was in each Cup at the beginning of the demonstration and duplicate it using the minimum amount of drops. They could also explain the chemisry involved in each step.

Woodrow Wilson TORCH Program