The basic points of this story will work with the attached demonstrations very nicely. However,
this story will only be as good as you make it. Adlib, personalize, and elaborate to the best of
your abilities. The props you use with the demos will definitely enhance the story, as will your
dress for the day. Moreover, I usually have a 2 liter graduated cylinder bubbling on my
demonstration table to one side, and a large, black, plastic cauldron bubbling to my other side.
They both are filled with water, and have several pieces of dry ice dropped in. I color the water
in the graduated cylinder with food coloring. {bubbling columns demo} A plastic pumpkin also
sits on my demonstration table next to a candle. You may also want to have some spooky music
or noises playing quietly in the background and turn off some of the lights in your classroom.
The basic premise of the story is as follows:
A young boy and his friends are out trick-or-treating on Halloween night. They
are nearing the end of their fun and they decide to visit the house of an old man who lives at the
end of a nearby street. Everybody is afraid of the man, but no one passes by his house on
Halloween night because he gives out the biggest candy bars. The group of boys approach his
house (describe how it looks here - old, dark, set back from the street, on a hill) and they all build
up the courage to go up to the door and ring the bell, all except one boy who is just too afraid.
The group of boys rings the bell and old man ___________ answers. As he drops a candy bar in
each bag, the boys turn and run down the long sidewalk back to the street. When they all gather
back around they look in their bags to see what they received. Each got their favorite candy bar,
and convince the one boy who remained that he should go up to the house to get his candy, but
none of them will go up with him. The boy finally goes up to the house (describe it in more
detail - the scarrier the better - remember to mention the pumpkin on the porch that is glowing
from the candle within). When he reaches the front porch he rings the doorbell. At that very
moment flames shoot out of the face of the pumpkin! {lycopodium powder demo done in a
pumpkin} The boy gets scared and, as he begins to turn to run, the front door opens. Old man
___________ says in a very deliberate tone, "And for you, a special gift!" as he drops a heavy
object into the boy's bag. He disappears into the house as quickly as he appeared. The boy runs
as fast as he can back to the street, screaming the whole way. Upon hearing this his friends
scatter, leaving him behind. When he gets far enough away from the house that he feels safe, he
ducks behind a tree to see what he received. He pulls out a large, dusty, but ornate bottle. He
begins to rub it to wipe away some of the dust. At this point a genie comes out of the bottle.
{genie in a bottle demo} When the genie appears he tells the boy that since he released the genie,
he must solve a riddle. If he solves it correctly he will be granted three wishes; if he solves it
incorrectly he will lose his life. He was given four hours to solve the following riddle:
Conquered by a little light,
A flame will take away its might.
The genie then gave him a map showing him how to find two special solutions which, when
mixed together, would provide him with a big clue as to the answer of the riddle. He was also
cautioned that he must burn the map after he finds the two solutions, but before he mixes them
together. (Describe the map in some detail, and describe how the map details a wooded location
very near the boys home, a place the boy was somewhat familiar with as he played there every
once in a while.)
He sets out to find the solutions. (This is where you need to adlib. I usually mention something
about finding the second solution up in a tree, in the crook of a branch. You can also get detailed
and mention the type of container the solutions are found in.) Upon having both solutions, he
combines the two solutions but nothing happens! {halloween colors demo, only mix solutions B
and C} He doesn't understand why nothing is happening. Then he notices that his hands are
bleeding, he is running out of time! {bloody picture demo} He remembers that he was to burn
the map before mixing the two solutions, so he rolls up the map, stands it up and lights it. {the
mysteriously rising napkin demo} Next, he adds a bit more of the solutions to see what will
happen. {halloween colors demo, add solution A to the already mixed B & C} He then sees the
clue and is able to solve the riddle. The genie appears and grants him his wishes.
Answer to the riddle...DARKNESS!
This experiment continues the theme of `clock' reactions. The
demonstration is known as the `Old Nassau Reaction', a clock
reaction which turns orange and then black (and has therefore also
been named the `Halloween Reaction') [1]. As Alyea describes [1]
`the formation of orange HgI2 was discovered accidentally by two
Princeton undergraduates ... when they were carrying out original
research on the inhibition, by Hg2+, of the Landolt reaction'. From
this, by reducing the Hg2+ concentration, the present demonstration
was subsequently developed [2].
The name `Old Nassau', comes from Nassau Hall which was
named after William III, King of England, Prince of Orange and
Nassau. Nassau Hall can boast of a colourful history [1]. `At the
time it was built it was the largest college building in North
America. On January 3, 1777 General Washington crossed the
Delaware to sieze the British ammunition stored there: his victorious
Battle of Princeton followed. In 1796 it was perhaps the earliest
undergraduate chemistry laboratory in the world,* where Dr John
Maclean, Professor of Chemistry, had the students, themselves,
carrying out chemical experiments. At that time Europe still practised
apprenticeship: colleges in the New World gave only lecture
demonstrations. In the late 1830s, several years before Samuel Morse
sent his first telegraph message, Dean Joseph Henry, using an
electromagnet, sent `clicks' from his office in Nassau Hall to his home
nearby to alert his servants that he was coming home shortly, and to
start heating water for his tea'.
The reaction in this experiment takes place in several steps
[5]. First, sodium metabisulphite reacts with water to form sodium
hydrogen sulphite:
Na2S2O5 + H2O ==> 2 NaHSO3
(10.1)
Hydrogen sulphite ions reduce iodate(V) ions to iodide ions:
IO3- + 3 HSO3-==> I- + 3 SO42- + 3 H+
(10.2)
Once the concentration of iodide ions is large enough that the
solubility product of HgI2 (4.5 x 10-29 mol3 dm-9) is exceeded, orange
mercury(II) iodide solid is precipitated until all of the Hg2+ ions are
used up (provided that there is an excess of I- ions).
Hg2+ + 2 I-==> HgI2 (orange or yellow)
(10.3)
If there are still I- and IO3- ions in the mixture, the iodide-iodate
reaction
IO3- + 5 I- + 6 H+==> 3 I2 + 3 H2O
(10.4)
takes place and the blue starch-iodine complex is formed,
I2 + starch ==> complex (blue or black)
(10.5)
A full account of the reaction can be found in Shakhashiri’s book [6].
Preparation. The following three solutions need to be
prepared.
A. Make a paste of 4 g of soluble starch with a few mils of
water. Pour onto this 500 ml of boiling water and stir. Cool to room
temperature, add 13.7 g of sodium metabisulphite (Na2S2O5) and make
up to 1 l with water.
B. Dissolve 3 g of mercury(II) chloride in water and make the solution
up to 1 l with water.
C. Dissolve 15 g of potassium iodate (KIO3) in water and make the
solution up to 1 l with water.
Demonstration. Mix 50 ml of solution A with 50 ml of solution
B. Then pour into this mixture 50 ml of solution C. After about 5
seconds the mixture will turn an opaque orange colour as insoluble
mercury iodide precipitates. After further 5 seconds the mixture
suddenly turns blue-black as a starch-iodine complex is formed. The
second colour change (orange to black) is not normally expected by
the audience and comes as a real surprise.
This experiment can be extended in several ways [5]. Diluting
all the solutions by a factor of two increases the time taken for the
colour changes to occur. Using a smaller volume of solution B speeds
up the reaction. The effect of changing the amounts and
concentrations of the various reactants cannot always be predicted
simply because of the complexity of the system. For example, if the
volume of solution B is doubled, the appearance of the orange colour
is delayed and the blue colour fails to appear at all.
If using mercury salts is not desirable, a somewhat simpler
clock reaction can be performed. This is known as iodine clock
reaction or Landolt reaction. The experiment is performed by mixing
equal volumes of two solutions, one containing 2 g dm-3 KIO3 and
H2SO4 0.03 M; the second - 0.4 g dm-3 of NaHSO3 in starch (2 g dm-3)
previously dissolved in boiling water. The initially colourless mixture
suddenly turns dark blue. There are several extensions to this
reaction as well, which can be found, for example in Ref. [7].
Safety. All soluble mercury salts are poisonous and should be
treated accordingly.
Goldenrod Paper Message
Use this special pH paper for some spooky Halloween
science
(Submit Review)
The term goldenrod is typically used to describe a color of paper - golden yellow. However, our
goldenrod paper contains a special dye that turns bright red when exposed to solutions that are
basic, like ammonia water or washing soda. We'll show you how to use this special colorchanging paper to develop a hidden message and make dripping, bleeding paper... complete with
your own handprint marked in "blood." It's a great acid/base lesson for the Halloween
Materials



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Goldenrod Paper
Cotton balls
Ammonia-water solution (household ammonia from the grocery store)
Candle or clear wax crayon
Secret Messages
1. Place a piece of Goldenrod Paper on the table. Make sure that the table is clean and the work
surface is dry.
2. Place a drop of water on one of the corners of the paper. Does anything happen?
3. Fill a jar with a small amount of ammonia water. Dip a cotton ball in the ammonia water and
wipe it across the top portion of the Goldenrod Paper. Save the bottom half of the paper for
step 5. Does anything happen?
4. As you continue to wipe designs on the Goldenrod Paper, notice that the paper does not stay
red forever. What is causing the paper to change back to yellow?
5. Use the old piece of wax candle to write a secret message (such as “Hi!” or “WOW”) across the
bottom half of the paper.
6. Wipe the cotton ball with ammonia water across the secret message to see what develops.
Bleeding Paper
1.
2.
3.
4.
5.
Place a piece of Goldenrod Paper on a clean, dry surface.
Away from the paper, spray your hand with "magic water" (the ammonia-water solution).
Tell your audience that when you touch the paper you can make it bleed.
Gently slap your hand down on the Goldenrod Paper... oh no! It's a bleeding handprint!
Your audience won't believe their eyes when you hold up the Goldenrod Paper, dripping with
your "bloody" handprint. It's the perfect Halloween experiment.
How does it work?
The ammonia on the cotton ball is a base and causes the dye in the special Goldenrod Paper to
change color. You probably noticed that the red color fades over time and the paper eventually
changes back to its original yellow color. Why? The carbon dioxide gas that is in the air we
breathe is slightly on the acidic side of the pH scale. The carbon dioxide reacts with the ammonia
on the paper to produce ammonium carbonate, which changes the pH of the paper to neutral
(roughly a pH of 7) and the dye changes back to yellow. If you use a stronger base like washing
soda, the red message will not disappear with just the carbon dioxide in the air. You will need to
use a stronger acid like lemon juice or vinegar to change it from red to yellow. You can also use
Goldenrod Paper as inexpensive pH paper to classify safe household products as being either
acidic or basic.