Magic into
Science
David A. Katz
Chemist, educator, and
consultant
Email: dakatz45@msn.com
Web site: http://www.chymist.com
A Chemical Genie
http://www.chymist.com/Chemical%20genie.pdf
OXYGEN
Joseph Priestley Carl Wilhelm Scheele
http://www.chymist.com/Preparation%20of%20oxygen.pdf
Carbon dioxide
http://www.chymist.com/Pour%20out%20a%20candle.pdf
Conservation of Volume
There are two cylinders:
Both are made from clear acetate sheets, 8 ½ x 11 inches
Cylinder 1: 11 inches high by 8 ½ inches circumference
Cylinder 2: 8 ½ inches high by 11 inches circumference
How do their volumes compare?
Note: Use A4 acetate sheets
http://www.chymist.com/Conservation%20of%20volume.pdf
Conservation of Volume
Calculate the volume of the two cylinders using the formula:
V = πr2h
where:
V = volume of cylinder
r = radius of the cylinder
Assume that the volume of cylinders, 1 and 2, are equal:
V1 = V2
Or
πr1 2h1 = πr2 2h2
Use the substitution:
r = c/2π (c = circumference of the cylinder, either 8½ or 11 inches)
c h
 c2 h 2

4
4 2
2
1 1
2
2
Cancel  and 42 from both sides of the equation to get
c12h1 = c22h2
For cylinder 1: c1 = 8 ½ inches and h1 = 11 inches
For cylinder 2: c2 = 11 inches and h2 = 8 ½ inches
Substitute the numerical values into the equation (but do
not multiply numbers):
(8 ½ x 8 ½) x 11 = (11 x 11) x 8 ½
Cancel between both sides to get:
8 ½ ≠ 11
This shows that the volumes of the cylinders are not equal but are proportional to their circumferences.
Hot and Cold
COLD HOT
Hot and Cold
Separate water by density
HOT
COLD
http://www.chymist.com/hot%20and%20cold.pdf
Sold by Flinn Scientific http://www.flinnsci.com/
Catalog no. AP4784
Sodium polyacrylate
A superabsorbent polymer
http://www.chymist.com/Disappearing
%20water.pdf
http://www.chymist.com/The%20fireproof%20balloon.pdf
http://www.chymist.com/Non-burning%20paper.pdf
Intermolecular forces: Decrease in Volume
ethanol and water
Intermolecular forces: Decrease in Volume
ethanol
water
http://www.chymist.com/Decrease%20in%20volume.pdf
Hydrogen Bonding
Increase in Volume
HCl + NaOH  NaCl + H2O
The volume increase is 18.5 mL/mol
Reference: Sam Katz, and Jane E. Miller, J. Phys. Chem., 1971, 75 (8), pp 1120–1125
http://www.chymist.com/Increase%20in%20Volume%202014.pdf
Hydrogen Bonding
Increase in Volume
Hydrated H3O+
O-O distance 2.59 Å
Hydrated OHO-O distance 2.50 Å
H2O
O-O distance 2.82 Å
Source: Martin Chaplin,
http://www1.Isbu.ac.uk/water/
index.html
Acids and Bases
• Svante August Arrhenius (1859 –1927)
– Acid produces hydrogen ions in water solution.
• Johannes Nicolaus Brønsted (1879‐
1947) and Thomas Martin Lowry (1874‐1936)
– An acid‐base reaction consists of the transfer of a proton (or hydrogen ion) from an acid to a base
pH
•
•
•
•
First introduced by Danish chemist Søren Peder Lauritz Sørensen (1868‐1939), the head of the Carlsberg Laboratory’s Chemical Department, in 1909 pH means ‘the power of hydrogen’.
Each value of pH means the H+ concentration changes by a factor of 10
As the H+ concentration decreases, the OH‐ concentration increases
pH 1
strong
acid
weak
acid
pH 7
neutral
weak
base
The pH scale according to the late Dr. Hubert Alyea, Princeton University
pH 14
strong
base
pH values for some common substances
Acids, Bases, and pH
• Acids, bases, and pH using red cabbage paper
– Buffers for reference
– Solutions of household products
• Illustrate indicator colors using serial dilutions to observe color changes
http://www.chymist.com/Visualizing
%20pH.pdf
Acids, Bases, and pH
• Acids, bases, and pH using red cabbage paper
– Solutions of household products
Acids, Bases, and pH
• Acids, bases, and pH using red cabbage paper
Phenolphthalein
Acid Base
?
http://www.chymist.com/phenolphthalein%20red.pdf
http://www.chymist.com/Disappearing%20Ink.pdf
Solutions:
Why does a substance dissolve?
Colloids
• Tyndall effect
Why is the sky blue?
Normal sky color
Pale blue sky near horizon
Chemistry and Light
Red sunset:
The Tyndall effect or why your car’s tail lights are red
http://www.chymist.com/red%20sunset.pdf
More details of these demonstrations can be found at
http://www.chymist.com
On the left‐hand menu, click on Compleat Chymical Demonstrator,
Laboratory Experiments, and/or Magic Into Science