Single displacements
Zn (s) + AgNO3 (aq) ---------> Ag (s) + ZnSO4 (aq)
Silver crystals form on zinc.
Zn (s) + Pb(NO3)2 (aq) ---------> Pb (s) + Zn(NO3)2 (aq)
Dull gray lead forms on zinc.
Zn (s) + 2HCl (aq) ---------> ZnCl2 (aq) + H2 (g)
Zinc reacts with the acid, and hydrogen gas is released.
2Al (s) + 6HCl (aq) ---------> 2AlCl3 (aq) + 3H2 (g)
Aluminum reacts with the acid, and hydrogen gas is released.
Zn (s) + CuSO4 (aq) --------> Cu (s) + ZnSO4 (aq)
Copper forms on zinc. Solution color becomes less blue.
Disposal
Aqueous solutions of HCl, Zn(NO3)2, AgNO3, and Cu(SO4)2 may
be flushed down the sink. Solutions of Pb(NO3)2 and Cu(NO3)2
should be evaporated, and the solid residue should be placed in
a solid waste disposal container. Solid metals should also be
placed in a solid waste container.
Double Displacement
I. 2 NaOH (aq) + CuSO4 (aq)  Na2SO4 (aq) + Cu(OH)2 (s)
Il. NaCl (aq) + AgNO3 (aq)  NaNO3 (aq) + AgCl (s)
lll. NaOH (aq) + AgNO3 (aq)  NaNO3 (aq) + AgOH (s)
iV. Na3PO4 (aq) + AgNO3 (aq)  2 NaNO3 (aq) + Ag3PO4 (s)
Gas producing
I. Na2CO3 (s) + 2HCl (aq)  2NaCl (aq) + H2O (l) + CO2 (g)
Il. CaCO3 (s) + 2HCl (aq)  CaCl2 (aq) + H2O (l) + CO2 (g)
Countertop Chemistry Experiment 13
Red, White, and Blue I
This colorful demonstration displays chemical reactions that can be performed
with common substances.
phenolphthalein solution aluminum foil magnesium sulfate heptahydrate Epsom
salt 6M ammonia household ammonia, colorless (10%), copper sulfate
pentahydrate, Roebic, Root Killer K-77
Procedure
1. Put 5 drops of phenolphthalein solution into the first beaker. This should
2.
3.
4.
5.
6.
be done very shortly before the demonstration, since it will evaporate
quickly.
Dissolve approximately 5 crystals of magnesium sulfate heptahydrate
and approximately 3-5 mL of water in the second beaker.
Dissolve 3 pea-sized copper sulfate crystals in approximately 3-5 mL of
water in the third beaker.
Wrap the cups with aluminum foil to enhance the curiosity of the
audience.
Pour the ammonia solution into each cup—using a volume that will
render the solution invisible to the audience.
Lift the aluminum foil masks to reveal the red, white, and blue colors.
Teacher's Notes
The red coloration is due to the presence of an indicator, phenolphthalein, in an
ammonia base.
The white coloration is due to a precipitate that forms when MgSO 4 reacts with
aqueous NH3. Mg(OH)2 is the insoluble white product.
The blue coloration is due to a complex ion that forms when Cu2+ ions react with
aqueous ammonia. The formula for the complex ion is Cu(NH3)4 2+
The phenolphthalein solution should not be placed into the cup or glass until
immediately before performing the demonstration. The indicator is a tincture (a
solution of the solid in alcohol) and will evaporate rapidly. After it evaporates, the
"trick" will not work.
Countertop Chemistry Experiment 24
The Witches' Potion
This demonstration shows that phenolphthalein is an acid/base indicator.
Materials
Substitutions
2-500 mL beaker
2 large, clear containers
4-250 mL beakers
4 tall glasses
phenolphthalein
3 M ammonia clear
colorless household ammonia
3 M acetic acid
vinegar
water
Procedure
1. Prepare four 250-mL beakers and label them 1-4.
o
o
In 1 and 3, put 5 drops of phenolphthalein.
In #2 and #4 put 5 drops of ammonia
If you prepare these ahead of time, cover them to reduce evaporation.
2. In one of the large beakers, put 20 drops of vinegar. Fill the other large
beaker with water.
3. Choose 5 volunteers: 4 witches and someone to read the poem.
Read : “Four witches made quite a commotion
When I invited them to create a potion.
Into four glasses went the magic brew,"
STOP
(Fill each glass 1/4 - 1/2 full with water. All will be clear and colorless).
4. Read:
"And into a rage the first witch flew: She shrieked,
'There's no magic in this drink.
To cast a spell, it must be pink!'
The second witch laughed, 'The pink is here.
Pour your brew in--the color will appear!'"
STOP
(Have Witch #1 pour her water into the glass of Witch #2. The
phenolphthalein will react with the ammonia and turn bright pink,
indicating the presence of a base.)
5. Read:
"The third witch shrieked, 'We need more!'
And gave her brew to Witch number Four."
STOP
(Have Witch #3 pour her water into the glass of Witch #4. The
phenolphthalein will react with the ammonia and turn bright pink,
indicating the presence of a base).
6. Read:
"Now there are two glasses of pink,
But no one asked me what I think!
I'll invoke my powers to make it clear'Be Gone Pink!' 'Watch it disappear!!'"
END
(Pour both glasses with the pink solutions into the glass container with
vinegar. The acid will neutralize the base and the liquid will be colorless
again).
Teacher's Notes
Phenolphthalein is an indicator that turns pink in the presence of
a base, but it is colorless in an acid. Because the
phenolphthalein solution is made with alcohol, it will evaporate
easily. You should plan to put the solutions in beakers just before
the demonstration to reduce evaporation.