The word allotrope just means different type or
alternate type. A number of elements appear naturally in more
than one
form at room temperature. The allotropes are usually due to the
crystal shape, or lack of crystal shape, or the
attachments of more than one atom of an element.

One of the easiest materials to see and play with in this
respect is sulfur. Most pharmacies will have containers of
of sulfur. This dull yellow powdery element is not only non- poisonous,
but it is ingestible. (You can EAT it!). Is there any good
reason for eating it? Yes! A spoonful eaten an hour before going
out into a pine forest will keep off the no-see-ums, or
chiggers, as they are called in the southern US. The sulfur
supposedly comes out of your body in your sweat and
discourages the insects. It would likely not be a good idea to
eat sulfur before a big date, unless your date ate some also.
It doesn’t smell very good. Don’t eat any of the sulfur from your
chemistry lab. No telling what other laboratory
chemicals have contaminated it.

Sulfur also has an allotrope that is easily seen. Into a test
tube put an amount of flowers of sulfur that is a depth of about
twice the diameter of the test tube. Heat this over a flame until
the sulfur is all melted. The melting point of sulfur is just a
few degrees above the boiling point of water. Pour out the melted
sulfur onto a clean disposable piece of paper.
(Careful. The liquid is hot and sticky. It will burn you if it
gets on you.) The sulfur quickly cools into a rubbery mass. It is

still sulfur. Very slowly as it sits, the rubbery mass will turn
back into a crystalline material. There are two crystalline
shapes of sulfur, a monoclinic and a rhombic along with this
amorphous (without crystalline shape) form.

Oxygen has two common allotropes. The familiar O2 is the common oxygen in the air. O3 is ozone, an allotrope of
oxygen. The most common way for ozone to be made is from natural
lightning. Ozone accounts for the "smell of rain"
that occurs around lightning strikes. The difference between them
is that the O2 molecule has two atoms of
attached to each other and the O3 molecule
has three atoms of oxygen attached to each other. Ozone is a
higher energy
form of free elemental oxygen. Generally after a while the ozone
gradually changes back to O2 in the air.

Carbon also has allotropes, but it is not so easy to change
the carbon from one allotrope to the other. In fact, if you
know of a good easy way to change carbon black into gem quality
diamonds, tell me about it. The three allotropes of
carbon are carbon black or lampblack, diamond, and graphite.
Carbon black is unattached carbon atoms. The black coloring
material in automobile tires, the blackening in shoe polish, etc.
are all carbon black. The soot from an oxygen-starved flame has a
lot of carbon black in it. Coal is mostly carbon black.

Pencil lead at one time was made with the element lead, but no
more. Graphite mixed with a very fine clay is molded into
a thin cylinder and placed in a wooden splint to make most common
pencils. You can see purer graphite in some
locksmith’s lubricant. As a naturally occurring mineral, graphite
is a dark gray, greasy-feeling material. This greasiness
comes from the shape of the carbon. In graphite the carbon is
attached in large sheets of hexagonally bonded atoms. The
sheets can easily move over one another, giving it that greasy

The bonds of diamond are tetrahedral. Each atom in a diamond
is linked to four other carbon atoms tetrahedrally in
three-space. Since the bonds are strong and the atoms of carbon
are small, diamond is very hard. It is a crystal, though.
If you tap a diamond in just exactly the right place, it will
cleave along the crystal face.

Now that you know something about allotropes, is the change
from one allotrope to the other a chemical change? Most
chemists would say, "No," but there is a material made
that has new properties. In the case of carbon or oxygen, there
are even some new chemical bonds made, even if it is between all
atoms of the same type.


Ionic compounds, those attached by an ionic bond, come apart
in water into the two ions. Sodium chloride is a good
example of an ionic material. Most ionic materials, as sodium
chloride, are in the form of crystals in solid form and in the
form of ions in the dissolved form in aqueous solution. You have
seen dissolving of sodium chloride before. A pinch of
table salt in a cooking pot half full of water very quickly
changes to the ions. How do we know the ions are in the
solution? The solution of table salt (or any other dissolved
ionic compound) can conduct an electric current by the
movement of the ions. The equation for this process is:

NaCl ===>
Na size=2>+ + Cl size=2>-

The sodium ions are attracted to the negative end (the oxygen
end) of the water molecules, and the chloride ions are
attracted to the positive end (the hydrogen end) of the water

Is this a genuine reaction or not? We say that a physical
change is one in which there is no change in the chemical
makeup of the reactant and the original reactant(s) may be
reclaimed by a physical process. A chemical change is one in
which there is a new material made.

Solid sodium chloride is definitely chemically different from
sodium ions-plus-chloride ions. The ions conduct electricity
and can react in ionic reactions. On the other hand, the material
can completely reclaimed by the process of evaporation
of the water. This is commonly done with sea water to get the
salt. Have bonds been broken? Yes, if you were to tag
specific sodium ions (radioactive tagging) to go with other
tagged chloride ions and dissolve them with non-tagged ions,
you would find that upon reclaiming the solid material the tagged
ions mixed with the untagged ions. The bonds of the
crystal have detached. The ions are loose in solution and make
bonds again as the crystal reappears. The ions do not
return to any previously determined position. The crystal itself
is only a conglomerate of ions in relative positions and not
a solid made of discrete molecules.

Some ionic materials, such as acetic acid, are only partly
ionized in water. We know this from the way the acetate ion
frees itself from the hydrogen ion. Acetic acid is a weak acid,
that is, the material may be completely dissolved, but there
is only evidence of a certain distinctive portion of the hydrogen


Biochemistry is the chemistry of living things. The number of
fascinating chemical changes that go on inside any living
thing is enormous. The variety of large, complex, extremely
intricate systems in a living thing are mind-boggling. Death of
a living thing is both a cessation of the biochemical processes
and a large number of biochemical reactions itself. Even
before the attack of the micro-organisms on a tree, the very
stopping of the everyday reactions cause a new set of
chemical changes to happen.


Blue vitriol is an old common name for cupric sulfate
pentahydrate. That name comes from the color, of course, which is

a strikingly beautiful blue, and ‘vitriol’ from the glassy
appearance of the crystals rather than any vituperative.
(Run for
that Webster’s!) Blue vitriol is one of a number of hydrated
crystals. These crystals, often sulfates or carbonates, attract
and semi-attach a definite number of water molecules to each of
the non-water parts to form a crystal lattice. A dot is
usually used in the formula to represent the association of the
water to the ionic part of the formula.

As with most hydrated crystals, gentle heating will free the
water from the copper sulfate. Upon heating, blue vitriol will
change from the glassy blue (about the color of the title of this
page) to a powdery light robin’s egg blue, releasing water
in the form of vapor*. The equation for this process is:

size=2>4 . 5H
size=2>2 O ===>
CuSO4 + 5H
size=2>2 O

The association of the water to the copper sulfate is in
exactly one to five mole ratio. The dehydrated crystal is
hygroscopic, that is, it fiercely grabs up water from the
atmosphere to replace into the crystal. If you place a drop of
liquid water onto the dehydrated crystal, it grabs up the water
with a sizzling sound, produces a bit of heat, and changes
to a color closer to the hydrated crystal.

Is this a genuine reaction or not? The exchange of heat, the
exact proportions of water and copper sulfate, and the
change of properties make good arguments for it being a genuine
reaction. On the other hand, the water stays water and
the copper sulfate formula does not change. The process is
reversible by simple physical process, either adding water or
heating to drive off the water.

*Copper sulfate is poisonous due to the copper ion. Copper and
other "heavy metals" such as lead and mercury are a
problem in cells of living things. Blue vitriol can present a
problem in doing this little dehydrating experiment because
larger crystals can explode from the heat and spray copper
sulfate all around. The powdery dehydrated crystal is also
dangerous. It is possible to breathe in enough of the powder to
poison yourself.


Carbon dioxide is a gas at room temperatures. It is an
important part of the respiration of living things and the carbon

cycle. Carbon dioxide in our atmosphere is a colorless, odorless
gas that is heavier than air. Put a piece of dry ice into a
deflated balloon and tie the open end of the balloon. The dry ice
will change into gaseous CO2 and fill the
balloon. This
balloon will drop quickly in the air. Carbon dioxide is a product
of complete combustion of any material that contains
carbon, so CO2 is a good material to put out fires.

Dry ice is solid carbon dioxide. It goes directly from a solid
to a gas at atmospheric pressures. (It takes higher pressure
for the liquid to appear.) This process, along with the reverse
process of the gas going directly to become a solid, is
called sublimation. Sublimation of CO2 at
atmospheric pressure occurs at -78.5 °C. Any wispy bit of
white haze around
dry ice as it sublimes is not carbon dioxide, but water. The
crystals of water come about from the solidification of the
water in the atmosphere. Stage or movie productions needing a
gentle haze on the ground have long relied on dry ice in
water. The dry ice sends up ice crystals into the air as the dry
ice bubbles under the water The ice crystals melt in the air
to make a wonderful little cloud. The carbon dioxide gas
dissolved in the water and around the water droplets tends to
make the cloud cling to the ground.

I know of someone who entered a High School Science Club float
in the Fourth of July parade with a large paper
cylinder on the float in the shape of a beaker. Under the beaker
was a pan of water with some pellets of dry ice to put
into it to form an evil-looking mist. The individual in question
became over enthusiastic about creating mist and put a
large amount of dry ice into the pan. By the time the float
passed the reviewing stand, the water had frozen.

One of the best ways to get a good refreshing drink in front
of a chemistry class is to place a pellet of dry ice into an
Erlenmeyer flask with about a third of the flask filled with
water. It is best to lean on the top of the flask with the palm
one hand. This increases the pressure on the carbon dioxide to
push it into the water. Stirring helps, so every so often
mix the flask around. As the liquid cools from the dry ice, even
more of the gas can be dissolved into the water. The
result, after a dramatic presentation and a calm swig of the
liquid, is called seltzer water. This is the same material that
gives any carbonated drink its fizz. Oh, one warning. Don’t drink
the dry ice pellet down with the water. The result is
even worse than swallowing a whole undissolved Alka Seltzer
tablet. Swallowing dry ice is dangerous. You can freeze a
part of your stomach doing that. Just try to explain that to an
emergency room doctor without laughing.

As carbon dioxide dissolves in water, there is another change.
The water becomes very slightly acid. Carbonated drinks
have a bit of a sour taste or ‘bite’ that comes from the carbon
dioxide. Once the ‘fizz’ has gone from such a drink, the
taste is ‘flat.’ The solution of carbon dioxide in water can
neutralize a base, so it is appropriate to call it ‘carbonic
acid,’ but there is no compound that can be isolated. The
equation for this process is:

CO2 + H2 O H2 CO3

The reaction is written with a double-sided arrow because it
is reversible. This has all the qualifications of a genuine
chemical reaction, except there is no way to isolate the product.
Carbonic acid only exists as ions in a water solution of
carbon dioxide.


Ammonia, NH3, is a gas with a distinctive
odor. There is no way to describe the smell to you any more than
there is a way to describe the smell of a pear. But you have
likely smelled ammonia. Many household cleaners contain ammonia.
Cats eat a large amount of protein. The protein has nitrogen in
it that must be excreted from the body. The contents of a cat pan
will give off a strong odor of ammonia as the deterioration
process of the waste goes on.

Ammonia has a number of uses. Some of the first refrigeration
units used ammonia as a coolant. It makes a fine coolant
material, but in the event of leakage from a cooling system,
ammonia is dangerous. In the amounts one would get from a leaking
cooling system ammonia can be a noxious gas. Ammonia can be made
directly from the nitrogen in the air and hydrogen gas by the
Haber process. It is used to make fertilizers and explosives.

Due to the amazing properties of water to dissolve materials
and the added properties of ammonia as a polar covalent material
with a very notable separation of charge, ammonia water makes a
wonderful cleaning material for glass and other materials.

In a reaction that has some similarities to the reaction of
carbon dioxide and water, ammonia dissolves in water to produce
ammonium hydroxide. We know there is some ammonium hydroxide in
the solution because we can make ammonium salts from it and the
solution is alkaline, but there is no such compound as ammonium
hydroxide. As the water evaporates from the solution, the
ammonium hydroxide escapes as water vapor and ammonia gas. The
name ‘ammonia water’ is a good way to describe a solution of
ammonia in water.

Does pressing ammonia gas into water produce a chemical
reaction? This is just as tough a question as the similar one
with carbon dioxide. We cannot isolate pure ammonium hydroxide,
but the solution is alkali and further reactions can happen with
the ammonium ion in solution.


Methane, CH size=1>4, is the smallest of the
hydrocarbons, those organic materials made of only carbon and
hydrogen. It has
been known as ‘swamp gas,’ a name that comes from the most
obvious place to see it. The bottom of swampy areas,
where much organic material from dead plants and animals sinks,
is the place where bacterial action breaks down the
complex biological materials to smaller molecules. The bacteria
make their living that way. Many of these bacteria are
anaerobic, that is, they are either inhibited or killed by the
presence of free oxygen. Methane is one of the products of
the metabolism of the bacteria. If you see a release of gas from
the bottom of a swamp, light it. If it burns, it is likely
methane. Once swamp air was thought to be the cause of malaria
(mal – bad, and aria – air in Italian) and
there was a
considerable effort to study methane from the swamps. As you
know, methane does not cause malaria, but is a pretty
good fuel.

Swamps are not the only source of methane. Some materials that
do not easily digest in people and animals may be
handled by bacteria in the intestines. Legumes (beans) are
notorious for having indigestible portions that react this way,
somewhat idiosyncratically, with people. Some dogs have a difficult
time digesting the cereals in inexpensive dog foods,
and they may develop a case of the winds from it.

Cattle have four stomachs for the fermentation and digestion
of even more difficult foods. Even so, there are many things
that the digestive system of cattle cannot handle, so bovine
burps have a high percentage of methane in them. Methane
from cow burps has been called a major pollutant of the earth’s
atmosphere. It seems there ought to be a way to collect
that and not only have a new source of fuel and clean the
atmosphere in the process. Methane is slightly lighter than air,
so collection bags on the backs of cattle would stand up from
the beasts, but methane is not so much lighter than air that we
have to fear floating cattle.   $|8-)


The white of an egg is almost all water and protein. The water
does not change significantly on cooking. The protein
does. What is a protein? Here is a rather simplified answer. A
protein is a very large molecule of repeating base units on
which are attached various side units. A single amino acid has an
amino side (-NH2 with the nitrogen attached to a
carbon) and a carboxylic acid side (-COOH with the carbon
attached to another carbon). The amino end of one amino
acid is attached to the acid end of the next amino acid. The
‘backbone’ of this huge molecule is the -N-C-C-O- series of
each amino acid. Each protein has a bare minimum of thirty amino
acids in it, usually several hundreds, if not thousands,
of amino acids. If a string of amino acids has less than thirty
or so amino acids, biochemists call the string a polypeptide.
There are about twenty different types of amino acid. Every
protein made by an individual has exactly the same amino
acids in exactly the same place. The pattern for each protein in
the body of a living thing is one of the important bits of
information passed down from generation to generation in genetic

The main idea we need to understand is that each protein is
very large, and that each protein has to be exactly right or it
will not do what it needs to do. Cooking does not usually destroy
the actual molecular formula for a protein, but it
destroys the shape of the protein from how it was folded and
re-connected and related to the environment around it. The
process of destroying the useful shape of a protein is called
denaturing. Cooking is only one of the ways to denature
protein. Adding acid or salt or lye (base) to the protein can
also denature the protein and these processes also tend to
kill bacteria and other things that would attack the protein.
Salting pork or fish were the best ways to preserve these
foods at one time. The proteins of milk curdle as they denature
in the acid of cheese. The starch is opened up and the
protein, what little bit there is, is denatured in corn when it
is mixed with lye for hominy. After denaturing, proteins are
not useful for whatever they were made, but only as food for
something else. The animal that eats the protein breaks it
down (digests it) into the individual amino acids and can use the
amino acids as a source of energy or as a source of raw
materials (amino acids) for building its own proteins. (Most
plants make their own amino acids.)

Is cooking an egg (denaturing a protein) a chemical reaction?
Possibly, but it certainly is a biochemical reaction. The
same obviously goes for a steak or any other source of protein.


Soap is made from neutral fat and lye. Sodium lye (sodium hydroxide
solution) or potash lye (potassium hydroxide in solution) when boiled
with neutral fats make glycerin and soap. A molecule of neutral fat is
split into one molecule of glycerin and three molecules of fatty acids,
twelve to twenty-two carbon chains of fat-soluble end and an organic acid
end that attracts the sodium or potassium in an ionic bond.

Soap making is an old technology from home chemistry. The fire place of
a home would be the source of heat and the cooking area. The meat cooked
over the flame would drip fat into a collecting pan. Ashes from the fire
have a small amount of lye in them. The ashes were washed with water and
the lye was concentrated by boiling most of the water out. The fat and lye
were put into a large kettle and boiled to make soap. It takes some
experience for a soap maker to get it right. If too much fat is added, the
soap can be too oily to use. If too much lye is added, the soap will be
caustic on skin and hair. The strong alkali of lye destroys protein. Now
you know the origin of the famous, ‘Grandma’s lye soap that will eat your face

Glycerin is a by-product of the soap-making reaction. (A by-product is
another material made that is not the main material desired from the
reaction.) Glycerin is an edible, sweet-tasting, oily-feeling liquid that dissolves in water
and some oils. Glycerin may be used as an antifreeze or as a hair dressing. Glycerin can
also be used as a constituent of foods. Many sugarless foods contain glycerin.


Have you ever seen soup bones for sale at the meat counter of a market?
Meat soups are made by gently simmering some of the less meaty abattoir
products. Bones, sinew, cartilage, and some meat make excellent soup.

Simmering is cooking in water by heating to just below the boiling point,
usually for several hours. Hot water leaches out proteins from bones and
cartilage that make a colloidal suspension in the liquid. If you take that
liquid with enough suspended protein and refrigerate it, the mixture becomes
a gel. The semi-solid nature of the gel suggests that at one point there has
been a change in the mixture from the protein being the dispersant and the
water a dispersing agent to the water being trapped within a loose protein
structure. In short, the gel has set. The gel made this way is called
gelatin. You can find gelatin in the drippings of meat cooked in
other ways also.

Gelatin desserts are just the leached protein, some coloring, flavoring,
and some sugar. Is it true, then, that gelatin desserts are good sources of
protein? Well, maybe.

The proteins of bones and cartilage are structural proteins. In bone the
protein serves as a support lattice-work for the hardening crystals of
(mostly) calcium compounds that give more rigidity to bones. This type of
protein has only a few of the amino acids that occur in proteins useful
for such things as enzymes and muscles. The amino acids in gelatin are all
produced by the human body. The essential amino acids, those that cannot be produced by the human body are not present in gelatin in any
significant quantity. For this reason, we call gelatin a source of incomplete protein.

Gels are interesting mixtures. You might say that the liquid and solid
phase of a colloidal suspension undergo a change wherein the roles of the
phases have reversed. The solid becomes the structural entity and the liquid
becomes the dispersed portion. A true gel will have a ‘ring’ to it. You can
see this in the ‘wiggle’ of gelatin. Many commercial toothpastes, hand
cleaners, and shampoos are gels. Firmly slap these into the palm of your
hand to feel the gel ring. The reason for offering the public these
commercial preparations in the form of a gel is that there is less likelihood
of separation of the materials or settling of the suspended portions.


Many years ago there was a large shallow salt sea in the western portion of
what is now the United States. The Bonneville Salt Flats and the Great Salt Lake
are almost all that remains of that sea. There are a few other places, mostly in
desert areas in which a small amount of water may remain with a lot of the
concentrated salts from that ancient sea. They are flat areas because they
were the bottom of the sea. There is an excess of the alkaline salts in these
areas called "alkali flats."

During the last two centuries of expansion of the United States toward the
west, many land travelers and explorers have found themselves attempting to
cross the desert areas on foot or by animal transport, only to run across the
alkali flats. The water from the pools in these areas is full of poisonous
alkali salts. The caricature drawing of these alkali pools has a sun-dried
skeleton or a sun-dried skull lying about near the pool, but such obvious
warning was not always there. Many a thirsty traveler learned too late that
the alkali pools were dangerous.

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