Water to Wine To Water To Milk
Purpose:
This demonstration is a good example of chemical change or a precipitate
reaction. It could also be an introduction to acids and bases.
It could be used as a demonstration in SCH11U Solutions and Solubility
Materials
Glass 1: 20 mL 0.1M NaOH solution
Glass 2: 20 mL of water and Phenolphthalein Indicator
Glass 3: 25 mL 0.1 M HCl solution
Glass 4: 20 mL Pb(NO3)2 in solution ( or AgNO3)
4 glasses (perhaps a wine glass and a beer mug)
Procedure:
Four glasses containing each of the clear colourless liquids are at the front of
the class. One glass is continually poured into the other. A pink liquid is
formed with the first mixture, a clear colourless liquid is formed with the
second mixture and finally a white precipitate is formed in the last mixture.
Theory
1. NaOH (aq) + Phenolphthalein (Indicator) = Indicator turns pink
2. Add enough HCl (aq) to neutralize product and therefore indicator turns
colourless.
3. Add this product to Pb(NO3)2 solution or AgNO3 solution and white
precipitate forms.
Hints for success
Drama is important. If the second glass is a wine glass, the first and third
glasses are water glasses and the last glass is a beer mug then you could tell
the following story.
"I will do a demonstration here to show how things can be changed. I have
four glasses of water here."
"With a little magic I may be able to change these into something that I
could use." Pour the first into the second. Show it to the class and attempt to
drink it.
"I shouldn't be doing this on school time." Pour the second into the third.
"This is a bit better."
"Perhaps I might try something else." Pour the third into the fourth and
attempt to drink it. Hide it quickly as it precipitates quickly.
Ask what has happened here. Was it magic? Have students hypothesize how
this may have occurred. And explain the chemical changes that have
occurred.
Safety Considerations
You are handling acids and bases so all precautions with these substances
should be considered. (safety glasses, lab coat, wash hands). Safe disposal of
the heavy metals is recommended.
References: (Forgive me but it has been a long time. I have probably
adapted this from something years ago. This has been around for a
while)