Transcript Technical Science

Technical Science
Introduction to Chemistry
Chemical Equations
Chemical Equations
 In this tutorial you will…
– Analyze a Chemical Equation
– Prove a Chemical Equation is Balanced
– Explain Reasons for Balancing Equations
– Explore Common Chemical Reactions
Analyze a
Chemical Equation
1 of 5
Home
 One of the main functions of chemistry is to
determine what will happen when substances react.
 A chemical equation is the method used to express
what happens during a chemical reaction.
 The chemical equation below outlines a familiar
chemical reaction. What is this telling you?
2Na + Cl2  2NaCl
 A chemical equation is really just a recipe.
 It tells you the amounts of specific ingredients that
are required to make a certain amount of a product.
2 of 5
Analyze a
Chemical Equation
 Let’s take a closer look at that chemical equation.
2Na + Cl2  2NaCl
Reactants
Products
First,The
you
The“ingredients”
should
“results”
notice
on the
on
that
the
right
the
left
equation
side
side is
broken
of the
into
equation
two parts
arewith
called
anthe
arrow.
The arrow represents
Reactants
Products
the chemical reaction.
3 of 5
Analyze a
Chemical Equation
 Identify the reactants and the products in the
following reactions.
N2 + 3H2  2NH3
Reactants
Products
BaCO3  BaO + CO2
MnO2 + 4HCl  MnCl2 + Cl2 + 2H2O
4 of 5
Analyze a
Chemical Equation
 Let’s take another look at that chemical equation.
2Na + Cl2  2NaCl
Coefficients
Subscripts
The
Coefficients
The
Subscripts
coefficients
The
subscripts
small
tell
tell
numbers
in
the
in
the
this
this
number
number
equation
equation
following
of
ofatoms
atoms
tell
tell
us…
or
You
The
probably
large
numbers
noticed
in
the
front
numbers
of
theus…
molecules
Two
that
the
are
sodium
that
Na
chemical
bonded
is
are
in
atoms
required
elemental
together
symbols
will
for
react
form.
to
are
the
make
with
reaction.
associated
formulas
with
are
chemical
called
Coefficients.
formulas
for the
2 Cl atoms
Coefficients
One
are
a single
bonded
chlorine
called
molecule
to
molecule
Subscripts.
form
the
ofamounts
anot
aproducts.
molecule
substance.
towritten
produce
of the
of
chlorine gas.
(Coefficients
reactants
ofare
one
and
are
the
out.)
1 Na is bonded
(Subscripts
They
Two
tomolecules
determine
reactants
1 Cl of
to one
make
of
and
the
are
sodium
asubstance
products.
not
molecule
written
chloride.
itself.
ofout.)
sodium chloride.
Analyze a
Chemical Equation
5 of 5
Home
 What do the chemical equations below tell you?
N2 + 3H2  2NH3 (NH3 is Ammonia)
1 molecule of nitrogen gas reacts with 3 molecules of hydrogen
gas to form 2 molecules of ammonia. Nitrogen and hydrogen
molecules are each formed from 2 atoms bonded together.
Ammonia is formed from 1 N atom bonded to 3 H atoms.
2MgO + Si  2Mg + SiO2
2 molecules of Magnesium Oxide (each with 1Mg bonded to 1 O)
react with 1 atom of silicon to form 2 atoms of magnesium
and 1 molecule of silicon dioxide (having 1 Si bonded to 2 O)
Prove a Chemical
Equation is Balanced
1 of 6
Home
Remember:tocoefficients
 An equation must be balanced
be useful.
of 1 are not written out.
 The equation below is not balanced. Can you see
what is missing?
2 Na + 1Cl2  2 NaCl
 There are no coefficients in the equation above.
 Coefficients determine the amounts of reactant and
product.
 The amounts of reactant and product are correct
when the coefficients make the equation balance.
2 of 6
Prove a Chemical
Equation is Balanced
 Prove the equation is balanced.
2Na + Cl2  2NaCl
Atom
Reactant
Product
Na
Cl
2
2
2
2
This
The
reaction
This
Coefficient
gives
is
abalanced
total
2all
and
of
two
because
the
lack
sodium
subscripts,
atoms
arehas
same
The
Remember,
We
First:
The
subscript
need
Second:
Third:
lack
Identify
to
of
akeep
balanced
aof
Count
Count
subscript
the
2of
track
and
the
the
the
chemical
of
ofnumber
and
number
types
lack
different
the
ofand
equation
of
coefficient
athere
ofcoefficient
atoms
numbers
atoms
elements
ofthe
of
on
and
number
ustwo
there
chlorine
and
are
types
2number
molecules
atoms
atoms
on
of
the
sodium
on
product
chloride.
side.
side.
2tells
on
chlorine,
same
atoms
sodium,
that
of
type
on
each
tells
are
and
tells
each
type
us
involved
usthat
side
that
onof
of
there
the
there
in
the
of
reactant
product
this
atoms
is
equation.
are
one
reaction.
2each
on
molecule
side.
side.
Na
both
atoms
So…
the
ofon
Each
molecule
has
Na
and
Cl.
There
You will
Let’s
are
chlorine
consider
2reactant
get
types
organized
the
that
of
both
reactant
and
atoms:
contains
coefficients
product
by1 creating
side.
Sodium
2 Cl
sides.
atoms.
&1a&subscripts
table
Chlorine
3 of 6
Prove a Chemical
Equation is Balanced
 Prove the equation is balanced.
MnO2 + 4HCl  MnCl2 + Cl2 + 2H2O
Atom
Mn
O
H
Cl
Reactant
1
2
4
4
Product
1
2
4
42
This
reaction
is
balanced
because
there
are
same
Chlorine
MnCl
There
are
tells
abalanced
us
total
up
there
inof
two
4ischemical
chlorine
one
products
molecule
atoms
MnCl
that
on
&
the
has
Cl
2H
O
tells
us
that
there
are
two
molecules
each
Remember,
4HCl
We
First:
need
Second:
Third:
tells
Identify
tells
akeep
that
Count
Count
us
the
track
that
there
all
the
the
of
there
of
are
number
number
the
types
four
isdifferent
one
and
equation
of
ofmolecule
atoms
numbers
atoms
elements
of
the
2 shows
2has
2.
2MnO
2tous
number
and
types
of
atoms
on
each
side.
Cl
1that
manganese
product
us
there
side
isbonded
1bonded
molecule
the
to
equation;
2to
of
chlorines.
chlorine
gas
oxygen
to
two
hydrogens.
having
same
atoms
of
type
one
on
of
each
are
this
and
hydrogen
each
type
involved
compound
number
side
on
of
bonded
the
in
the
ofreactant
product
this
and
atoms
equation.
reaction.
itone
has
on
side.
chlorine.
both
So…
the
2 tells
So,
2 from
with
there
Cl
is
MnCl
1Mn
atoms
atom
and
bonded
2to
from
2together.
Cl
the
Cl&
Sothere
there
are
four
hydrogen
and
two
Oxygen
You
So
There
one
will
Let’s
manganese
are
consider
are
get
reactant
42the
four
organized
types
both
hydrogen
and
of
bonded
coefficients
product
by and
creating
and
Mn,
two
sides.
four
&
oxygens.
O,
aatoms.
subscripts
chlorine.
H,
table
2atoms:
2. Cl
4 of 6
Prove a Chemical
Equation is Balanced
 Prove the following reaction is balanced.
2NO + 2CO  N2 + 2CO2
Atom
N
Reactant
2
Product
2
O
4
2
4
2
C
5 of 6
Prove a Chemical
Equation is Balanced
 Prove the following reaction is balanced.
P4O10 + 4HNO3  4HPO3 + 2N2O5
Atom
P
Reactant
4
Product
4
O
22
4
4
22
4
4
H
N
6 of 6
Prove a Chemical
Equation is Balanced
Home
 Prove the following reaction is balanced.
C6H12O6 + 6O2  6CO2 + 6H2O
Atom
C
Reactant
6
Product
6
H
12
18
12
18
O
Explain Reasons for
Balancing Equations
1 of 5
Home
 You know that a reaction is balanced when the
coefficients make the number and type of atoms on
each side of the equation equal.
2Na + Cl2  2NaCl
 You can also prove whether a reaction is balanced.
 But why is it so important to balance an equation?
 Why wouldn’t you want to write the equation like
this… Na + Cl2  NaCl
 There are at least three reasons why it is important
to balance a chemical reaction.
2 of 5
Explain Reasons for
Balancing Equations
 Look at the unbalanced equation below.
2 Na
Na Na
+ Cl2  2 NaCl
Cl Cl
Na Cl Na Cl
This
TheWhen
unbalanced
means
The
Notice
Where
the
Law
if Now
we
proper
there
did
ofequation
start
Conservation
that
we
are
coefficients
are
with
other
two
following
above
two
chlorine
chlorine
atoms
of
suggests
are
Matter.
atoms
in
go?
ofplace
chlorine
that an
It has
we
on
This
The
to
atom
must
the
go
and
law
Law
reactant
somewhere.
of
end
the
states
chlorine
ofwith
equation
Conservation
that
side
two
just
It
matter
but
atoms
iscan’t
disappeared.
balanced,
only
of
can
of
just
1Matter.
chlorine.
chlorine
not
disappear.
be
Thiscreated
leads
all us
the
orto
This
destroyed
atoms
on
a very
is
theagainst
can
product
important
only
be accounted
the
changed
side.
law.
law inin
for.
chemistry.
form.
3 of 5
Explain Reasons for
Balancing Equations
 Look at the partially balanced equation below.
2Fe + 3H2O 
Fe Fe
Fe2O3
+ 3 H2
O
O-Fe-O-Fe-O H-H
H H
H-H
O
O
H-H
H H H H
However,
As
Notice
Hydrogen
itWhat
turns
the
If
inhydrogens
athis
coefficient
out,
chemical
gas
partially
the
is odorless
hydrogen
from
equation
in balanced
front
water
and
atoms
of
is colorless
on
the
not
equation
the
bonded
H2 reactant
side
that
are
would
together
properly
the
not
iron
accounted
make
to
and
balanced,
but
form
this
the
explosive.
equation
for
another
oxygen
you
on the
may
are
product:
balance?
product
balanced.
miss side.
That’sWhere
not a product
did
aHydrogen
potential
those
you
hydrogen
would
Gas
product.
(Hwant
) to go?
overlook.
2atoms
Explain Reasons for
Balancing Equations
4 of 5
 What does the unbalanced reaction below tell you?
2 Na
+ Cl2 
Na Na
Cl-Cl
2 NaCl
Na-Cl Na-Cl
Balancing
The
This
Remember,
An
We
amounts
reaction,
unbalanced
know
the of
equation
chemical
the
aseach
written,
ingredients
equation
substance
tell
equations
tells
usishow
and
you
like
are
are
products
much
that
adetermined
recipe
recipes.
sodium
of each
reactant
atoms
They
but we
tell
(Na)
by
that
is
don’t
the
the
required
react
tells
amounts
coefficients
know
you
with
and
how
allchlorine
ofthe
how
much
the
that
ingredients
much
ingredients
are
gas
of each
assigned
molecules
of each
is
but
required
needed.
product
(Cl2)
to
doesn’t
and
form
thewhen
tell
molecules
amounts
you
the
will
how
equation
of
be
ofproduct
much
produced.
sodium
isofbalanced.
you
chloride
eachcan
oneexpect.
(NaCl)
to use
Explain Reasons for
Balancing Equations
5 of 5
Home
 Why is it important to work with a balanced
chemical equation?
 If an equation isn’t balanced, it implies that atoms
suddenly appear or disappear. This goes against
the Law of Conservation of Matter
 If an equation isn’t balanced, you may miss a
product that is not easily observed.
 An equation is a chemical recipe. If it isn’t
balanced, it is like a recipe that doesn’t include any
amounts. It would be useless to try to make
something from such a recipe.
Explore Common
Chemical Reactions
1 of 16
Home
 A chemical reaction is a recipe that lists amounts
and type of both reactants and products.
 In this section you will analyze common chemical
reactions.
 The goal is to give you the background information
necessary to determine the type of product when
given the reactants.
 There are seven of these reactions. You have
already had experience with some of them.
 The following slides will present each of these
common chemical reactions.
Explore Common
Chemical Reactions
 Salt Formation
Metal + Nonmetal  Salt
2 Na + Cl2  2 NaCl
4 Fe + 3 O2  2 Fe2O3
There
Metals
Metals
Most ismetal
combine
In
combining
a special
theobjects
specific
with
case
with
must
nonmetals
example
ofoxygen
this
be protected
type
above,
is
toof
also
form
reaction.
called
from
salts.
Iron
corrosion
A
Metals
reacts
oxygen
specific
or
with
react
so
oxidation.
example
this
Oxygen
with
reaction
Oxygen
isto
This
shown
form
doesn’t
reaction
(aabove
Iron
nonmetal)
occur.
III
can
with
Oxide.
be a
This
costly
sodium
Which
is one
to
onemetal
form
reason
because
is commonly
areacting
Metal
for
degrades
painting
Oxide
with
known
metal
chlorine
(a
metal
as
salt)
rust.
objects.
objects.
gas.
2 of 16
Explore Common
Chemical Reactions
3 of 16
 What product would be formed from the reactants
listed below.
2 Mg
+ O2  2 MgO
Metal + Nonmetal 
Salt
(Oxygen)
(Metal Oxide)
TheThe
product
InMg
chemical
this(magnesium)
case,
is Magnesium
equation
the saltisthat
aisOxide
metal.
balanced
forms
(MgO)
Mg
withtakes
Othe
(oxygen)
coefficients
onbea a+2metal
ischarge
a nonmetal.
shown
oxide
&O
above.
is –2.
2 will
Metals
So one
because
combine
Magnesium
the
with
nonmetal
nonmetals
balances
is one
oxygen.
to form
Oxygen.
salts.
Explore Common
Chemical Reactions
 Base Formation
Metal Oxide + Water  Base
Na2O
+ H2O  NaOH
Remember
The
You
Bases
base
now
that
represent
aknow
base
is formed
that
is type
ana important
metal
isofSodium
compound
oxideclass
Hydroxide.
is athat
of
salt.has
–1).
compounds.
aNa
Itmetal
ishas
composed
abonded
+1When
charge
of
to athe
you
metal
&Hydroxide
hear
OH
bonded
the
hasterm
aIon
to
–1oxygen.
caustic
(OH
charge
or
+1one
soalkaline,
the formula
Here,
You
it isthe
also
probably
is NaOH.
metal
knowisin
water
(one
sodium
reference
Na
is H(Na
with
to
)a base.
OH)
2O.
4 of 16
5 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
listed below.
CaO + H2O 
Metal Oxide + Water

Ca(OH)2
Base
TheCaO
product
The(calcium
chemical
is Calcium
oxide)
equation
Hydroxide
is a Metal
is balanced
Oxide.
(Ca(OH)2)
Ca takesasonitHais2O
+2
shown
ischarge
Water.
above.
& OH is –1.
Metal
So one
Oxides
Calcium
combine
balances
withtwo
water
Hydroxide
to form ions.
bases.
6 of 16
Explore Common
Chemical Reactions
 Acid Formation
Nonmetal + Water  Acid
Compound
SO3
+
H 2O

H2SO4
Remember
The
Nonmetal
Acids
acid
an
are
that
acid
compounds
another
isisformed
type
important
ofare
iscompound
Sulfuric
two class
or more
Acid.
that
of has
compounds.
Hahas
Hydrogen
anonmetals
+1 charge
You
ion(s)
have
covalently
&
bonded
heard
SO4 has
to
of
bonded.
avarious
a nonmetal.
–2 charge.
acids;
+iswith
The
Here,
formula
stomach
theYou
nonmetal
isalso
acid,
H2SO
know
acid
is4.the
(two
rain,
water
sulfur
Hbattery
trioxide
H2O.one
acid,SO
(SO4-2
3))
acetic acid (vinegar), citric acid (in fruits),
ascorbic acid (vitamin C), etc
7 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
listed below.
CO2 + H2O  H2CO3
Nonmetal
Compound
+ Water

Acid
CO2The
(carbon
product
dioxide)
is Carbonic
is a nonmetal
Acid (H
compound.
2CO3)
HThe
takes
on H
a 2+1
Oequation
is
charge
Water.
&
chemical
is CO
balanced
3 is –2.
SoNonmetal
two Hydrogens
compounds
combine
one Carbonate
with water
ion.
as it isbalance
shown
above.
to form acids.
Explore Common
Chemical Reactions
8 of 16
 Neutralization
Acid + Base  Salt + Water
HCl + NaOH  NaCl + HOH
+1stable.
You
When
The
The
probably
A
H+
The
This
An
you
salt
water
ions
pairs
acid
forms
take
is aof
also
forms
releases
metal
of
an
acids
water
atom
noticed
antacid
from
bonded
and
which
hydrogen
replaced
that
the
forto
is
remaining
OHan
inavery
each
this
H
nonmetal.
upset
ions
reaction
ions.
other
of
stomach,
ions.
bases
the
+1
+1
The
whatmake
acid
A
The
you
The
base
pairs
to
and
metal
are
them
H
form
releases
the
really
atoms
(from
isvery
two
base
thedoing
hydroxide
traded
reactive
new
Na
the
“neutralize”
acid)
substances.
is
from
partners.
neutralizing
compounds.
bonds
OH
the-1each
base.
ions.
to other.
your
-1
-1is
TheThe
But
HThis
from
stomach
The
acid
when
This
reaction
nonmetal
in
the
they
the
this
type
acid
OH
react
case
isofbonded
with
often
isreaction
(from
is
the
together,
HCl.
acalled
Cl
base
tothe
the
The
from
(the
sometimes
neutralization.
base).
the
OH
base
antacid).
the
H+
from
acid.
ions
is NaOH.
the
andbase.
The Nathe
from
called
This
OHThese
the
makes
aions
double
base
ions
bond
H-OH
bonded
form
replacement
tightly
or
the
toHsalt
the
O each
(water).
NaCl
Cl
reaction.
from
other.
the acid.
2to
9 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
listed below.
2 HCl + Mg(OH)2  MgCl2 + 2 HOH
Acid
+
Base

Salt
+ Water
The
other
product,
thethe
water,
salt,
is base.
H-OH
HCl
is One
anproduct,
acid.
Mg(OH)
2 is a
The H
The
isAcids
(from
Magnesium
chemical
the acid)
equation
Chloride
takes
on
(MgCl
balanced
aform
+1 charge.
react
with
basesis
to
2)
TheMg
with
OHtakes
(from
the acoefficients
on
the
a +2
base
charge
)shown
has&a Cl
above.
–1ischarge.
–1.
Salt
and
Water.
So, one Magnesium
So, water isbalances
HOH or two
H2O.Chlorines
Explore Common
Chemical Reactions
10 of 16
 Metal Plating
1st Metal + Salt  2nd Metal + Salt
Zn + CuSO4  Cu + ZnSO4
You
can
see
zinc
replaced
the
metal
copper.
(the
zinc),
Zinc
This
isThe
type
more
of
reactive
reaction
is
very
copper
common.
so
this
The
The
The
salt
second
metal
that
metal
isthe
is
produced
inoriginal
(product)
solidthan
elemental
is
formed
comes
form.
from
from
the
the
This
type
thesalt
ofplace
reaction
of
the
isthe
copper
often
called
in
asalt.
single
Ittook
isThe
found
reaction
in
will
take
and
place.
metal
plating.
original
metal
metal
portion
and
isbatteries
dissolved
the
of
nonmetal
water
original
portion
asthe
salt.
ions
of the
started
replacement
with
Copper
reaction.
II
&metal
However,
IfWe
copper
it will
metal
only
occur
placed
if the
inSulfate
original
aissolution
The
metal
here
original
iswas
Zn.
The
salt.
salt
CuSO
4.
ended
with
Zinc
Sulfate.
is more
of zincreactive
sulfate,
than
nothing
the metal
would
in
happen.
the salt.
11 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
listed below. (Magnesium is more reactive than Silver)
Mg + 2 AgNO3  2 Ag + Mg(NO3)2
Metal 1
+
Salt

Metal 2
The
One
other
product,
the Ag(NO
metal,
the salt,
is) is
Silver
Mg(NO
(Ag))
Mg
is aproduct,
metal.
3 2 is a salt. 3 2
TheMetals
The
silver
Themagnesium
chemical
wasreact
replaced
equation
is now
by
the
an
is producing
balanced
ion
magnesium.
Mg+2
can
with
salts
+2
-1
Mgwith
donated
with
coefficients
its
two
nitrate
becoming
shown
ions
a NO
Mg
above.
3 ion.
aand
newthe
salt
bye-replacing
the
metal.
+1 ions
forms
TheaAg
new
salt.accepted
(Magnesium
the e-Nitrate)
and
went back to elemental form.
+ Salt
12 of 16
Explore Common
Chemical Reactions
 Combustion
Organic + Oxygen  Carbon + Water
Dioxide
Compound
CH4 + 2 O2 
CO2
+ 2 H 2O
These
This
Another
One
Organic
fuels
is product
a reaction
may
word
compounds
be
for
is the
that
Carbon
combustion
gasoline
you
contain
Dioxide
encounter
iniscarbon.
your
burning.
(CO
daily.
car,
2) the
The
chemical
equation
is gas
balanced
natural
The
This
reaction
reaction
In
gas
this
other
that
of
case,
allows
organic
heats
product
it is
us
your
methane
compounds
toisrelease
home,
Water
coal,
energy
(H
(CH
with
oil
) from
or the
2O)
4oxygen
with
the
shown
above.
toOxygen
food
produce
you
organic
iscoefficients
carbon
eat
simply
tofuel
power
Oxygen
dioxide
sources.
your
and
Gas
body.
water
(O2)
The basicisreaction
called combustion.
is the same for each.
Explore Common
Chemical Reactions
13 of 16
 What product would be formed from the reactants
listed below.
C3H8 + 5 O2  3 CO2 + 4 H2O
Organic + Oxygen  Carbon
+ Water
Dioxide
Compound
There is an additional product in combustion
The
C3two
HThe
products
isequation
an
any
organic
combustion
compound.
reaction
8 (propane)
reactions
chemicalin
and
that
is is
energy.
balanced
It reacts
are
always
with
Carbon
Dioxide
a combustion
Water.
reaction
The
with
production
theoxygen
coefficients
ofinenergy
shown
is and
the
above.
reason
to formwe
carbon
and water.
burn dioxide
these fuels.
Explore Common
Chemical Reactions
14 of 16
 Polymerization
Monomer + Monomer  Polymer
C2H3Cl + C2H3Cl  -[C2H3Cl]-[C2H3Cl]The
Small
Polymerization
A
The
The
monomer
process
molecules
polymer
process
of is
polymerization
that
of
ais
are
relatively
putting
also
isbonded
formed
used
small
small
by
together
in
isliving
molecules
used
this
molecule.
case
to
things.
make
form
is
larger
create
(monomers)
Proteins
aThe
molecules.
synthetic
chain
are
monomers
together
polymers
of vinyl
substances
Thechloride
in
to
groups
ofthis
form
amino
like
example
larger
of
molecules.
plastics,
acids.
monomers
molecules
areStarch
nylon,
are
andIt(polymers)
cellulose
isvinyl
called
chloride
are
called
Polyvinyl
styrofoam,
is polymers
called
molecules
polymers.
Chloride
polymerization.
etc.
of simple
C 2H
(PVC).
sugars.
3Cl
15 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
listed below.
C2F4
+ C2F4
Monomer
(Tetrafluoroethylene)
+
 -[C2F4]-[C2F4]-
Monomer 
Polymer
(Teflon)
The product is Teflon.
C F4 are monomers.
It is a polymer2 of
the small C2F4 monomers.
Monomers combine to form
Polymers.
Name Salts with
Multivalent Metals
16 of 16
Home
 Write the general reactants and products
Formation
of a Salt
Metal + Nonmetal  Salt
Formation
of a Base
Metal Oxide + Water  Base
Formation
of an Acid
Nonmetal Compound + Water  Acid
Neutralization
Metal
Plating
Combustion
Polymerization
Acid + Base  Salt + Water
Metal 1 + Salt  Metal 2 + Salt
Organic
+ Oxygen  Carbon + Water
Compound
Dioxide
Monomer + Monomer  Polymer
Technical Science
Introduction to Chemistry
You have Completed
Chemical Equations
Created by John W. Pluemer