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Fire is a chemical reaction and so is life itself!
You mean there is a fire burning in me? Keeping me alive?
Well, yes, in a sense. It isn't a flame like on a candle, but
chemical reactions "power" living things. You and me
and mice and wheat and other living things can be thought of in two ways.
Dead or alive. A dead thing is just a bag of chemicals like the atoms
and molecules we talked about in the earlier sections. But living
things are a series of chemical reactions! Chemical reactions
are the subject of our last Ancient Element, FIRE.
Great. You've mentioned chemical reactions a lot already. What
exactly are they?
Chemical reactions CHANGE chemicals, making a new chemical from
another.
Hey, what exactly is a chemical?! Exactly.
Hmmm. You know it's funny I hadn't mentioned it before, but chemicals
are just about everything!. The word "chemical" can
refer to any substance - as atoms or molecules or even the purity
or state it is in.
How about ice melting into water? Is that a chemical reaction?
Yes, it is. When ice melts, what happens to the molecules?
They move around. Move apart. The water molecules in the ice are
in solid regular groups, so ice is made of crystals of water.
When it melts, the pattern falls apart and flows. It becomes a
liquid. Only the weak forces change. Do weak forces count?
Of course they count. That change from a regular pattern, a crystal,
to a drop of water is a chemical change. Weak forces are responsible
for a great deal of Alchemy. Including many of the weak interactions
that we call life.
I think chemical reactions are the real exciting part of Alchemy.
It allows an Alchemist to make new chemicals from old ones. Right?
Right. The making of another molecule, a synthesis,
(pronounced "sin-the-sis") is
at the very core of an Alchemist's work. We do that by causing
and controlling chemical reactions. Chemical reactions can turn
atoms into molecules (making bonds), molecules into atoms (breaking
bonds) or molecules into other kinds of molecules (breaking old
bonds and making new ones). Plus we must not forget the weak forces.
You can think of chemical reactions as the making and breaking
of bonds. Weak bonds, strong bonds and metal bonds. All bonds!
All this bond making and breaking in chemical reactions involves
energy.
What exactly is energy?
Energy is "the ability to do work".
Like harvest crops or clean the room?
Well, more like the work of the universe. The universe has its own kind
of work and "rules" of work.
The universe has rules?
Oh, yes. The rules of the universe (often called "the laws
of nature") are the foundation upon which our universe is
built and works. The universe isn't concerned about the harvest
or your room. "Work" to the universe is things like
heat, light, sound and electricity.
Sounds complex.
Well, it can be, but we aren't going to go deeply into it. I don't
want to turn this into a physics class.
Good. Do all chemical reactions need energy to make them go? Do all of them need heat to go?
Ah, now you have asked two different things and both are
complex. Heat is only one form of energy. There is also energy hidden
in the chemicals and sometimes that hidden energy can be huge. Lets
take this one step at a time in order to keep it simple. First we will
talk about heat as if it were the only kind of energy.
That sounds like a good idea to me. I understand heat. It's so obvious.
Yes, it is. OK, lets concentrate on heat.
Some chemical reactions need you to add heat to them to make
them "go". They need to absorb heat to make them run. Chemical reactions that absorb heat are called endothermic.
You seem to know a lot about ancient words. What do you think
"endothermic", means?
Ah, "endo" means "under" and "thermic"
has something to do with temperature, I think.
Right.
So endothermic means "under temperature".
Cold!
Right! Endothermic reactions suck heat out of their environment
(their surroundings) to make the endothermic reaction "go".
That makes the environment colder. Cold is just the lower energy in the environment caused by the endothermic reaction.
I bet all chemical reactions are endothermic because you need
to add energy to make anything "go". It just makes sense.
It takes energy to harvest crops and it takes energy to clean
my room.
Quite a lot of energy. But the rules of the universe can
play
pleasant tricks on you. You see you said "energy" when you should have
said "heat". You are confusing the two. Let's stick to heat. Some
chemical reactions PRODUCE heat!
How?
Chemicals have a hidden "on board" energy stored
in them. That energy is mostly hidden in the bonds - the kind of
bonds they are, the amount of wiggle in them and so on. Also,
some energy is stored in the molecules' wiggles or vibrations.
There's a lot of hidden energy in chemicals! (And much more energy
hidden in the nuclei of the atoms, but that's nuclear physics.)
Can you imagine a way a chemical reaction might give off heat?
Let's see. A chemical reaction changes one chemical into another, so....
Hmmm... let me guess.
If the starting chemical has more energy than the new chemical,
the chemical reaction will give off the extra energy. Perhaps as heat. Is that
how it happens? It kind of makes sense.
Yes! That is exactly what happens in an exothermic reaction.
Exothermic reactions produce energy from the chemical change and release that energy as heat.
I see.
Exothermic reactions burn off some heat as they make a lower-energy molecule.
Endothermic reactions take in heat to make a new
molecule with more "hidden" energy stored away.
Right.
Hey. Wait a minute. Is fire an exothermic or endothermic reaction?
What do you think? Think about how a fire starts and progresses.
That's what confuses me. All I need is a tiny flame to turn a
pile of wood into a huge amount of heat. I put in a tiny amount of
heat but I get out a huge amount of heat. The fire pays me
back a million fold in the heat it produces, but it needs my help
to get it started.
That's right. DO NOT confuse the energy change caused by the chemical
reaction with the conditions that started it. True, you need
a tiny flame to start a big fire, but the fire "pays you
back" many times over. So the whole chemical reaction eventually
gives off heat.
So fire is an exothermic reaction.
Right. Fire gives off heat, so it is an exothermic reaction.
OK. That makes sense. But why does it need me to get it started?
Why the tiny flame?
A piece of wood must first be heated to very high temperatures
before it begins to burn. Once it is burning it produces heat
of its own, from the chemical reaction (chemical changes). It
is this "self generated heat" which then feeds energy
to the rest of the wood causing it to burn. This is why fires,
once started, can get out of control. Can't they?
They sure can. Hey, what about an explosion? What causes an explosion?
Well, an explosion is caused by a very fast reaction. The energy is given
off very quickly as heat, light, and sound. The sound
produces a shock wave that carries away the energy in a destructive
"blast".
So explosives are dangerous and useful because they are fast chemical
reactions?
Yes, exactly. Explosives, like dynamite and fireworks, are very
fast reactions. A similar but slower chemical reaction occurs
in a flame. A candle flame produces heat and light. And even a
wee bit of sound.
DON'T put your HEAD close to a flame to listen to it! You'll set
your hair on fire!
OK. OK! Sorry.
Another inch and you would be! Trust me, candles make wee sounds.
Anyway, a flame is usually a slow, steady reaction.
The difference between an explosion and a flame is the SPEED of
the chemical change. Some chemical changes occur very rapidly
and the release of energy is fast and impressive - like a firecracker.
A candle flame is slower. Some chemical reactions are so slow
you hardly notice them from one day to the next - like rust.
Oh. Rust is a chemical reaction. So a poorly kept sword rusts
because of a chemical reaction?
Yes. The iron in a sword is a metal and it is pretty good at picking
up oxygen. The iron atoms in the sword pick up oxygen atoms to produce iron
oxides. Rust!
Let's start talking and writing like a proper Alchemist.
The material at the start of the chemical reaction is the reactant
and is placed on the left side of the equation. An arrow points
the way to the final products. Like this
REACTANTS ------> PRODUCTS
I see. So the chemical equation for ruining a sword is
SWORD + AIR ------> RUSTY SWORD
Yes, but how would an Alchemist explain and write it?
Oh, well, like this
iron + oxygen ------> iron oxide
Or even better would be to use the symbols.
Yes, but for now,
I think we should go slow. Any questions about rusty swords?
Yeah. Why does a sword rust faster if it's wet? The oxygen comes
from the air. Right?
Right. That's a very good question. The water helps the iron to
rust into iron oxide, but it doesn't end up in the product. Some
important parts of Alchemy work that way. More on that later.
What about a copper coin? Or the copper wire heated in the flame?
What would that be in terms of the atoms involved and the words
Alchemists use?
Ah, let's see. The coin and wire are copper (Cu, just the metal)
and it is what we start with so it is the reactant.
Right.
And the copper oxide?
That's the product and it is made of copper oxide (CuO).
Right. So what would the chemical equation look like?
Like this
Cu -----> CuO
I suppose it gets the oxygen from the air.
You suppose correctly. However, the equation you wrote is incomplete.
It is missing an important ingredient. The oxygen! Without the
oxygen you could not make the copper oxide. So let's include the
oxygen from the air. Remember, a molecule of oxygen is O2.
Oh, right. I get confused here. When you say "oxygen," I am never sure if you mean the oxygen atom or the oxygen molecule.
That is a matter that confuses many beginners but when an Alchemist uses the term "oxygen" in referring to a reaction, they are usually referring to the oxygen molecule. Oxygen atoms by themselves are extremely rare, at least in areas where humans dwell.
It might help to review some of the common substances and ions and their names. If we share the same vocabulary, then our conversations will be much simpler.
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hydrogen H2 | hydrogen ion H+
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oxygen O2 | oxide O-2
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chlorine Cl2 | chloride Cl-
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fluorine F2 | fluoride F-
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bromine Br2 | bromide Br-
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iodine I2 | iodide I-
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nitrogen N2 |
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| sulfide S-2
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sodium Na | sodium ion Na+
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potassium K | potassium ion K+
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calcium Ca | calcium ion Ca+2
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magnesium Mg | magnesium ion Mg+2
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aluminum Al | aluminum ion Al+3
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copper Cu | copper Cu+2
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iron(II) | iron(II) ion Fe+2
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iron(III) | iron(III) ion Fe+3
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I'll try to remember those.
Now back to the copper reaction. I just need to write in the oxygen as a reactant (on the left side). So the "complete" equation is
Cu + O2-----> CuO
Right?
Or could I write
Cu + O2 --> CuO2
Would that also be correct?
No! Consider the product. If the formula for the product was CuO2, then you would have one copper ion and two oxide ions. The +2 charge on the copper ion and the two -2 charges from the oxides would result in an overall charge of -2 on the molecule. Since the product does not have a charge, then this formula cannot be correct. But in CuO, the charges exactly cancel each other our to make an electrically neutral ionic molecule with no overall charge.
I get it. So the reaction must be
Cu + O2-----> CuO
Right! That is a complete equation. It shows all you need to make
a copper coin "rust". It is complete, because it has all the reactants
and products, but it is NOT balanced. A balanced equation
has the correct NUMBER of the needed ingredients and the substances
they produced. Have you noticed that the left side of the equation
has two oxygen atoms (in the one oxygen molecule)?
Yeah, but there's only one oxygen on the right side in the "rust".
Where did the other oxygen atom go?
Good question. Where do you think it went?
I don't know. Maybe to another copper atom?
Yes, another copper atom is used up. It makes another molecule
of copper oxide (CuO).
I need two atoms of copper to make that the two molecules of copper
oxide. I'll just rewrite the equation to include two copper atoms
to begin with, as reactants. And that will give me two molecules
of copper oxide (2CuO) as products.
2Cu + O2-----> 2CuO
Right?
Right. In 2Cu + O2-----> 2CuO, the copper and oxygen atoms
are all accounted for. That is a complete and balanced chemical
equation. All students of Alchemy must learn how to make complete,
balanced equations.
Looks easy enough. It's just a puzzle.
Yes it is. Some puzzles are easier than others. That one was pretty
easy. Later on I'll teach you how to do the harder ones.
Anything else I should know about writing equations?
Yes. Sometimes you will see chemical reactions written with an
arrow pointing BOTH ways like this
REACTANTS <------> PRODUCTS
The double arrow is to remind you the reaction is "reversible".
Reversible! I bet you don't get too many of those!
You bet wrong! Chemical reactions are reversible if you change
their conditions. The hard part is changing the conditions to
make the reaction run in the other direction. It's easier said
than done.
So it is a worthless idea, these reversible reactions!
Not worthless. Priceless! There's a difference.
In theory, all chemical reactions are reversible. In practice
few are.
Alchemists spend a great deal of time making (synthesizing)
molecules which would rather not be made. Some molecules that
Alchemists make are very hard to synthesize. So Alchemists search
for the right conditions of temperature, pressure and other things
that will force a chemical reaction to go one way instead of another.
I see what you mean. If you could find the conditions which would
reverse the rusting of a sword, you would have a magic recipe.
In mythical terms, yes. But modern Alchemists have replaced chants
and mysticism with reaction conditions.
There must be millions of chemical reactions. How do you remember
them all?
I don't! No one does. The methods for making new chemicals from
old chemicals are called synthesis techniques. By the 21st century,
Alchemists had discovered millions of ways to make millions of
chemicals. All those "magic recipes" can be found in
libraries.
Do you have some way to keep track of them all?
Yes. Many ways. It all boils down to the special words Alchemists
use to describe molecules and how to make them.
All chemical reactions can be classified as one of three types:
combination, decomposition or replacement.
Combination joins two (or more) substances to create a
more complex substance.
Like copper and oxygen combining to form copper oxide (2Cu + O2
------> 2CuO)?
Right. That's a combination. The opposite reaction is decomposition.
Decomposition breaks a substance into two (or more) simpler
substances.
So it is the reverse reaction from before. 2CuO ------> 2Cu
+ O2 is an example of decomposition.
Right. Combination and decomposition are the reverse of each other.
They don't always refer to the same reactions but
they can. For example
2Cu + O2 ------> 2CuO
is a combination reaction.
But the decomposition reaction is
2CuO ------> 2Cu + O2
The combination of copper and oxygen into copper oxide is the
reverse of the decomposition of copper oxide back to oxygen and
copper. If the reaction conditions are right, you get more combination
than decomposition and you end up with copper oxide being produced.
So the reaction can go either way.
Right. It's reversible.
Under standard reaction conditions you
end up with copper oxide because combination "wins out"
over decomposition in this example of copper and oxygen.
What is this "standard conditions" all about?
Those are the "standard" temperatures and pressures.
Alchemists like to think in terms of standard conditions
in order to keep clear (to each other) what conditions they are
talking about. Most Alchemists define standard conditions
as zero degree centigrade (0oC) and one atmosphere of pressure
(1 atm).
So, standard conditions are just normal pressure and a cold day.
Ah, yes, but we Alchemists are more specific and define it as
0oC and 1 atm. Alchemists agreed on those as the standard conditions
because they are so common (on Earth).
Let me get this straight. Under standard conditions copper combines
with oxygen to form copper oxide. Right?
Absolutely. Copper oxide forms under standard conditions. However, if we change the conditions to something "non-standard"
we could reverse the reaction. For example, at a different temperature
decomposition "wins" and the copper oxide will not form.
You're left with copper and oxygen.
Exactly, what "non-standard" conditions will cause copper
oxide to decompose?
I don't know, off-hand. However, I'm sure it is known and can
be found in a library. Those specifics aren't important (now) in your education.
OK?
OK. Combination and decomposition are reversible examples of the
same chemical equation.
Right. They illustrate the reversibility we have been talking
about. But most of the time one or the other "wins".
And which one "wins" depends upon the reaction conditions.
Under standard conditions, combination "wins". Does
combination always "win" under standard conditions?
No, no! Each chemical reaction is different. In the equation
2Cu + O2 ------> 2CuO
this combination will occur under standard conditions.
However, the break up of hydrogen peroxide into oxygen and water is
a completely unrelated decomposition reaction
2H2O2 ------> O2 + 2H2O
and it occurs at standard conditions. (At 0oC and 1 atm hydrogen
peroxide decomposes.)
I see what you mean. Combination and decomposition describe what
happens in a reaction and they are reversible examples. Sometimes
combination "wins" and sometimes decomposition "wins".
It's the conditions of the reaction that decide which one "wins".
Right. Under standard conditions copper oxide is made from copper
and oxygen (a combination) while under those same standard conditions
hydrogen peroxide decomposes. Under "non-standard" conditions
(of some sort) these reactions will reverse. Got it?
Yeah. You really have to keep track of which equation you are
talking about and which conditions.
Absolutely! That is the main "work" of an Alchemist -
discovering the right equations and reaction conditions that
will give him what he wants.
By the way, about this chemical equation I have written for the
decomposition of hydrogen peroxide
2H2O2 ------> O2 + 2H2O
Is it a complete and balanced equation?
Ah, lets see..... No! The oxygens don't balance.
Don't they? How many oxygens are on the left, in the reactant?
Two in each molecule of hydrogen peroxide gives a total of four
oxygens in the reactant. But the product has two oxygens in the
one molecule of oxygen molecule and one in both water molecules......
Oh, that's four oxygen atoms on both sides! The oxygens balance.
Maybe the hydrogens don't balance. Let's see. The two molecules
of hydrogen peroxide have a total of four hydrogens. And the hydrogens
in the products are all in the water molecules. Two hydrogens
in each water molecule and two water molecules are in the product
so the total product has four hydrogens too!
Right! It's a balanced (and complete) chemical equation for hydrogen
peroxide's decomposition.
2H2O2 ------> O2 + 2H2O
I see.
You know, you really have to work it out. It kind of looks
wrong at first, but they do add up to the same atoms in the reactant
as in the product.
That's right and that's an important lesson. Most of the time
you can't tell if an equation is balanced (or complete) by just
a casual glance. You have to work on it to prove it to yourself.
OK. You said there were three chemical reactions.
Oh, yes.
The third type of chemical reaction is a replacement reaction.
Replacement substitutes one atom or part of a molecule
for another.
For example?
For example, if you dropped a piece of copper into sulfuric acid
the copper atoms would replace the hydrogens. Like this
Cu + H2SO4 ------> CuSO4 + H2
I see. Atoms are traded around.
Is replacement a reversible reaction?
Of course! All simple chemical reactions are reversible.
But you said there were only three types. If the replacement reaction
has a reverse reaction there would be four types. The forth reaction
would be a "unreplacement" reaction.
No. You've got yourself confused. Easy enough to do with this
lesson.
The equation I have written is reversible. All equations
are reversible, even the ones that have been written to look
as if they only go one way. I wrote it in one direction because
that is the direction that "wins" under standard conditions.
Can you tell me the reverse equation (under some "non-standard"
conditions)?
Sure, it is just the reverse.
CuSO4 + H2 ------> Cu + H2SO4
That's right. Now tell me, is that a combination, decomposition
or replacement reaction?
Ah, it's not really a combination reaction because you don't end
up with a more complex molecule, just a different one. And it
isn't a decomposition reaction because you don't end up with a
simpler molecule, just a different one. Actually, it's another
replacement reaction!
Right, and now you have your answer to your question. Replacement
reactions are their own reverse! It just depends...
...upon the reaction conditions! I get it.
So all chemical reactions are either combination, decomposition
or recombination. And they are all reversible if you change the
reaction conditions.
Aye, that's right. Be aware, that some chemical reactions are
very complex. There can be mixtures of thousands of chemical reactions
of these three types. However, we can always see one or more of
these three types of reactions in any reaction, if we look close
enough. Also be aware that while all chemical reactions are reversible
if you change the reaction conditions, it isn't always easy to
do that.
So, that's all there is to chemical reactions?
Oh, goodness, no! There's plenty more. This has been a good introduction
to the general ideas. Let's get into some details.
OK. What is happening with these bonds breaking and reforming?
It must involve the electrons. Right?
Aye, it certainly does. We spoke of chemical reactions as involving
any kinds of bonds, including the weak forces. That is certainly
true, but most Alchemy involves changes in the strong bonds. That's
not to say that weak forces and bonds are not important. They
are! But changes in weak bonds are often so simple or delicate
that we will not use them as a subject to study here.
So I will learn only about the strong bonds? That doesn't sound
like a complete education. You're cutting corners, wizard.
No, I'm making things simple. The chemical reactions involving
the strong bonds are the focus of most introductory Alchemy classes
because once you understand them, the reactions involving weak
bonds are very easy. Although the weak forces operate differently,
the overall ideas are similar.
So, you'll teach me all about chemical reactions involving strong
bonds, but I can figure out the weak bond reactions from what
I learn.
Yes. We can spend our time now focusing on chemical reactions.
But there are only three types of chemical reactions. Combination,
decomposition and replacement. Right?
Well, yes and no.
What!?
The three types of reactions you named are one way to look at
chemical reactions. And it is true that any chemical reaction
can be classified as one of those three types. But there are other
ways to think about chemical reactions.
How?
By thinking about what is happening during the reaction. For example, one importsnt type of reaction is the one that causes fire. We Alchemists call it combustion.
I thought you said that there is a fire in me. Does that mean that combustion is happening inside me?
Oh, it certainly is, but it is not exactly the same combustion that happens in a flame, really.
How can it be the same and different too?
Ah, good question. Combustion really refers to more of a "family" of reactions, usually combination reactions. The combustion that creates a flame is in the same family as the combustion that warms your insides.
Do they have anything in common? How can I tell that a reaction is a combustion or not?
They all have one important thing in common: they involve something reacting with oxygen in the form of O2. I'll give you an example. Coal burning is the reaction
C + O2 ---> CO2
which forms carbon dioxide.
This looks like a simple reaction.
Oh, 'tis, but it is a very important reaction because it warms our homes all winter.
True.
I have a question, why can't we call CO2 carbon oxide; wouldn't that be simpler?
The problem, you see, is that there are different carbon oxides. You are trying to name CO2 as if it is composed of ions, but it is a covalent compound, not an ionic compound. Carbon dioxide is CO2 and carbon monoxide is CO.
What would I call CO3?
That molecule does not exist. But if it did, it would be called carbon trioxide.
I see a pattern here! You are putting the name of the first element in the formula and then saying how many atoms of the second element there are.
Correct. And I am using more ancient languages to tell the number of atoms. One is "mono," two is "di," three is "tri." However, if the first element would have a "mono" prefix, I don't bother saying it.
When would the first element have any other prefix?
As in C2O2.
So that would be dicarbon dioxide?
Exactly.But back to the combustion of coal.
C + O2 ---> CO2
Is this reaction balanced?
It looks balanced to me. There are two oxygens and one carbon on the left and two oxygens and one carbon on the right.
Precisely. A fine balanced combustion reaction.
Are there other combustion reactions?
Yes, have you seen the gas that burns?
Of course, it sometimes lights the swamps at night.
Well, that light comes from the combustion of methane
CH4 + O2 ---> CO2 + H2O
Really? It look much like the coal combustion. It produces CO2.
Carbon dioxide. Let's use the words of the Alchemist.
Yes, carbon dioxide.
How observant of you. In fact, carbon dioxide is the fate of every carbon atom in the reactants in a combustion. The products of a combustion can only be certain molecules. Usually, the products are carbon dioxide and water.
But why is there no water in the products of coal combustion?
Maybe you can answer that question for yourself.
Me? Well...
Oh, I see. There is no hydrogen in the reactants, so there is no way to make water, which contains hydrogen.
Excellent! Yes, but consider the combustion of another gas, ethane. The formula for ethane is C2H6. Will it produce carbon dioxide and water, or just carbon dioxide?
It must produce water, too. Ethane has hydrogens, and you said that the fate of every hydrogen in the reactants is to become part of a water molecule. So the reaction should look like
C2H6 + O2 ---> CO2 + H2O
Correct. But you still look puzzled.
I just noticed that the ethane combustion reaction is not balanced. There are different numbers of atoms on the left and right. Ho! The same is true for the combustion of methane! Does that mean that the reactions are written wrong?
No, it just means that we need to balance them. But these reactions are a good starting point. Perhaps after a rest, we will talk about balancing.
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Assignment for Lesson 16
You are to answer the following questions in your own words. Please post the questions with your answers in the text box below to submit your work. Some questions will require you to obtain information from outside sites, be sure to cite your sources!
1. Name the following compounds: LiCl, AlBr3, MgO, K2S
2. Write chemical formulas for the following compounds: calcium sulfide, aluminum oxide, potassium fluoride, sodium sulfide
3. Name the following covalent compounds: NO2, BrF3, SF2, N2O3
4. Write chemical formulas for the following compounds: sulfur trioxide, hydrogen fluoride, diphosphorus trisulfide, dihydrogen oxide
5. Name the following compounds (decide first whether the compound is ionic or covalent): IF3, SO2, K2O, CaF2
6. Write formulas for the following compounds (decide first whether the compound is ionic or covalent): sodium oxide, sulfur monoxide, aluminum chloride, phosphorus mononitride.
7. Write a chemical equation for nitrogen monoxide and oxygen gas make nitrogen dioxide. Is this reaction balanced? Justify your answer.
8. What type of reaction is did you write in the previous answer?
9. Write a chemical equation for sodium and water makes hydrogen gas and sodium hydroxide (NaOH). Is this reaction balanced? Justify your answer.
10. What type of reaction is did you write in the previous answer?
11. Write a chemical equation for nitrogen triiodide makes nitrogen gas and solid iodine (I2). Is this reaction balanced? Justify your answer.
12. What type of reaction is did you write in the previous answer?
13. Write a chemical equation for the combustion of ethyl alcohol (C2H6O). Is this reaction balanced? Justify your answer.
14. Write a chemical equation for the combustion of sugar (C12H22O11). Is this reaction balanced? Justify your answer.
15. Write a chemical equation for the combustion of ibuprofen (C13H18O2). Is this reaction balanced? Justify your answer.
16. Write a chemical equation for the combustion of buckminsterfullerene (C60). Is this reaction balanced? Justify your answer.
17. Find out the shape of buckminsterfullerene. Name one allotrope of buckminsterfullerene.
18. Find out who buckminsterfullerene was named for, and why that name was chosen.
19. Is the process of ice melting exothermic or endothermic? Explain how you know your answer is correct.
20. If you wanted to warm your hands on a cold day, would you want to be close to an exothermic reaction or an endothermic reaction?
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