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SPI 0807.9.2 Identify the common outcome of all
chemical changes. (a new substance is created)
SPI 0807.9.8 Interpret the results of an investigation
to determine whether a physical or chemical change
has occurred.
SPI 0807.9.10 Identify the reactants and products of a
chemical reaction. ( reactants  products)
SPI 0807.9.11 Recognize that in a chemical reaction
the mass of the reactants is equal to the mass of the
products (Law of Conservation of Mass).
SPI 0807.9.8 Interpret the results of an investigation to
determine whether a physical or chemical change has
occurred.
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

A physical change/ reaction is
a change that alters the shape
or appearance of a material,
but does not change the
material into any new
substances.
For example water can freeze,
melt, or evaporate, but it is still
just H2O…
All physical reactions are
reversible!
 Imagine
a chemical formula… Obviously
there are elements/ compounds/
molecules…
 Lets
 You
say this…
H2O + Fe  Fe + H2O
have the same two things going into a
reaction and coming out the other side… so
nothing actually changed as far as how
atoms are arranged...
 NaCl
(salt)  NaCl (still salt)
• This is just salt… and something is done to it…
but it is still salt… so maybe someone froze it, or
melted it, or something but the chemical haven’t
changed.
 C6H10O5
(cellulose)  C6H10O5 (still cellulose)

Physical change/ reaction doesn't affect
structures or combinations of atoms.

Examples
• Magnetizing things… (atoms don’t change just because
you magnetize them)
• Boiling, melting, freezing stuff… (again… atoms don’t
change)
• Dissolving things into liquids  you can always
evaporate the liquid out to separate them if no bonds
have formed…
• Dicing/ shredding/ cutting/ breaking
• Making a mixture
 2 or more types of
matter (substances)
mixed together
 Not in specific
amounts
 Can be separated
physically or filtered
 Can get everything
back easily
SPI 0807.9.8 Interpret the results of an investigation to determine
whether a physical or chemical change has occurred.
 What
is the difference between physical
and chemical reactions?

Physical – Alters form or appearance
mother-in-law  mother-in-law
 Chemical
– Produces a new substance
mother-in-law 
woman hitler
A
chemical reaction is a process in which
one set of chemical substances (reactants) is
converted into another (products). The new
substances will have different properties
than the reactants…
 It
involves making and breaking chemical
bonds and the rearrangement of atoms.



A chemical change is a change
in to elements or compounds
that forms one or more new
substances.
The new substances are made
of the same elements as the
original substances, but are
now in different combinations.
Many chemical reactions can
not be reversed.
SPI 0807.9.8 Interpret the results of an investigation to determine
whether a physical or chemical change has occurred.
A
color change is
often a sign that
chemical reaction has
occurred.
 This
color change is
permanent and
doesn’t change
back…
 Another
way to tell if
a chemical reaction
has taken place is if
there is a change in
odor.
 Again, permanent,
and doesn’t change
back…
 Gas
Production is
another line of
evidence that shows
chemical change!
 The
production of a
gas where there
wasn’t that type of
gas before…
A
huge, quick
change in
temperature is
another sign of a
chemical reaction.
A
change in heat,
light, or sound
can indicate a
chemical change.
1.
Change in form  Example: burning a
piece of paper… burning a piece of
wood…
2.
Digestion – Hundreds of chemical
reactions take place during digestion.
3.
Respiration – Likewise… the lungs take in
air and separate everything from the
oxygen in chemical reactions.
4.
Combustion/ Catching Fire when heated…
SPI 0807.9.8 Interpret the results of an investigation to determine
whether a physical or chemical change has occurred.


There is a noticeable change between reactants
and products in a chemical reaction…
Something isn’t the same…


 2HgO  2Hg + O2
Oxidized mercury Mercury + Oxygen
So, obviously, the reaction split apart the oxidized
mercury creating two new substances… not new
in that we’ve never seen them before… but new
as in they weren’t there when we started…
 H2
+O2  H2O2
 O3
+ Fe  FeO3
 NaCl
 O2
+ H2O  H2O + NaCl
+ CH4 + energy  CO2 + H4

Physical changes only
effect physical properties.


Physical changes produce
no energy.



Physical changes produce
no new substances the
atoms are arranged the
same way in the products
and reactants.
Physical changes are
generally easy to reverse.


Chemical changes will
effect both physical and
chemical properties.
Chemical changes produce
energy generally in the
form of heat, light, or
sound.
Chemical changes produce
new substances the atoms
rearrange and form new
compounds.
Chemical changes are not
easily reversible without an
additional chemical
reaction.
A
new substance is made through
breaking and/or forming bonds.
• The compounds or elements don’t stay the
same… They either form new bonds, break their
previous bonds and stay apart, or some
combination, but something has to change from
reactants to the product for a chemical reaction
to take place…

The breaking of chemical bonds never releases energy to the external
environment.

Energy is only released when chemical bonds are formed. In general, a
chemical reaction involves two steps:
• 1. The original chemical bonds between the atoms are broken, and
• 2. New bonds are formed.
• These two steps are sometimes lumped into one event for simplicity,
but they are really two separate events. For instance, when you burn
methane (natural gas) in your stove, the methane is reacting with
oxygen to form carbon dioxide and water. Chemists often write this as:

CH4 + 2 O2 → CO2 + 2 H2O + energy
 In
physical science lab, Ben and Jerry added
small pieces of magnesium to hydrochloric
acid. They noticed that bubbles formed, the
test tube got hot, and the magnesium
disappeared. What is a sign that a chemical
reaction has taken place in this experiment?
• Odor
• gas is produced
• magnesium disappeared
• decrease in temperature
 Which
process best demonstrates a
chemical change in distilled water?
• Freezing water.
• Separating water into its elements.
• Calculating density.
• Dissolving sugar in water.
 When
most chemical reactions take
place, some __________ in the reactants
must be broken down, a process that
requires energy.
• Compounds
• Chemical bonds
• Precipitates
• Products
 Martin
cut an apple in half and placed it
on the table while he talked to his
friends. After a while, the cut sides of the
apple changed color. Martin determined
that the apple
• underwent a physical change.
• began to dissolve in the air.
• reacted with the acid in the table top.
• underwent a chemical change.
 Water
molecules are each made of two
hydrogen atoms and one oxygen atom.
Under the right conditions, however, the
atoms can be separated. This type of
change in a substance’s properties is
• Chemical.
• Physical.
 Scientists
study the characteristics of
substances to better understand the
natural world. Which of the following is
not a physical or chemical characteristic
of a substance?
a. Odor
b. Density
c. Cost
d. Color
 What
is the main difference between a
physical and chemical change?
a. In a physical change, only composition
changes.
b. In a chemical change, only composition
changes.
c. In a physical change, both form and
composition change.
d. In a chemical change, both form and
composition change.
 What
kind of chemical change might be
observed in cars that are driven in
coastal areas or in areas that use salt to
treat icy roads?
• Precipitation
• Formation of salt crystals
• Dents and dings
• Corrosion of metal
 Which
of the following is an example of
chemical change?
a. Ice melting in a glass
b. Wood burning in a fireplace
c. Defrosting food in a microwave oven
d. The addition of food coloring to a glass of
water
 Which
of the following is NOT a chemical
change?
a. Juice that ferments into wine
b. Salt being mixed into water
c. Silver tarnishing in the open air
d. Antacid that neutralizes stomach acid
 Which
of these is common to all chemical
changes?
• A change of state occurs.
• A change of color occurs.
• New substance is produced.
• Heat is released into the air.
A
student takes four samples of a silver,
metallic solid and subjects each piece to
different treatment.
• Piece 1: The solid is hammered into a flat sheet.
• Piece 2: The solid is heated in a flame until it melts.
• Piece 3: The solid fizzes when acid is dropped on the
surface.
• Piece 4: The solid is place in a beaker of water and it
floats.
SPI 0807.9.10 Identify the reactants and products of a chemical
reaction.
 Reactants
are the
elements or
compounds to the left
of the equation/
arrow. They are what
goes into a reaction
 Products
 H2O2
 H2O2
 H2 + O2
are the
elements or
compounds to the
right of the equation/
arrow. (the arrow is
pointing at them)
They are what comes
out of a reaction…
 H2 + O2
 One
thing that is important in chemistry is
being able to tell the difference between
reactants (before) and products (after)…
 2Mg
2
+ 02  2MgO
H202
 Na
 2 H20 + 02
+ O2  NaO2
 2SO2+O2+
2H2O 
H2SO4
 Which
of these is a reactant in this
chemical reaction?
• Hydrogen
• Nitrogen
• Oxygen
• Water
 What
are the reactants in the rusting
process?
• iron oxide
• water and iron
• iron and oxygen
• water and iron oxide
Let’s clear up the confusion…
 Endothermic
reactions absorb energy / heat
(making everything around them colder)
(endo- inside)
 Exothermic
reactions release energy/ heat
(making everything around them warmer)
(exo- outside)
 Not
all chemical reactions release
energy… So it is not a common outcome
of all chemical reactions… half, tops..
SPI 0807.9.11 Recognize that in a chemical reaction the mass of
the reactants is equal to the mass of the products (Law of
Conservation of Mass).
 During
a chemical reaction, matter is
neither created nor destroyed.
 The
number of atoms stays the same no
matter how they are arranged. So their
total mass stays the same
 Atoms in = atoms out
 The
Law of
Conservation of mass
states that matter can
neither be created or
destroyed…
 The
mass of the
reactants must equal
the mass of the
products.
 The
mass of the reactants has to equal the
mass of the products…
 The
number of atoms in the reactants also
has to equal the number of atoms in the
product…
 ______This_____
 Or
_______This____
else it is incorrect and needs redone.
A
chemist mixes 20 grams of sodium with 5
grams of chlorine. The product is sodium
chloride.. Given then law of conservation of
mass… how much mass should be produced in
the product?
 2Na
 20
+ Cl2  2NaCl
g + 5 g = _____
A
chemistry student combined 3 grams
of sodium and an unknown amount of
water and the outcome was 25 grams of
NaH2O. Given the law of conservation of
mass… how much water was in the
reactants?
 Na
+ H2O  NaH2O
 The
product of a chemical reaction is 21
grams of iron sulfide (FeS)… If 17 grams
of iron (Fe) was a reactant then how much
sulfur (S) was used?
 Fe
+ S  FeS
 2Na
+ Cl2  2NaCl
 20 g + 5 g = _____
 Na+
H2O  NaH2O
 3 g + ___  25g
 2HgO
 2Hg + O2
 100g =  ___ + 23g
 CaCO3
 CaO + CO2
 Cl2 + 2NaBr  2NaCl + Br2
 CaO + H2O  CaOH2
 2HCl  H2 + Cl2
 2H2 + O2  2H2O
 2H2O2  O2 + 2H2O
 Zn + 2HCl  H2 + ZnCl2
 2H2 + O2  2H2O2
 The
mass of a rusty bicycle is found to be
slightly greater than the mass of the same
bicycle before it rusted. The change in
mass indicates that the rusting process —
a. is a physical change
b. involves an energy-to-matter conversion
c. decreases the density of the metal
d. involves metal bonding/ reacting with other
atoms
 Which
of these would support the idea
that mass is conserved in a reaction that
produces a gas as a product?
a. Heating the reactants to ensure the reaction
occurs in a gaseous state
b. Subtracting the mass of the gas from the mass
of the solid and liquid products
c. Mixing the reactants and measuring their total
mass
d. Trapping the gas and measuring its mass
 If
all the reactants in a chemical reaction are
completely used, which of the following
statements accurately describes the
relationship between the reactants and the
products?
• The products must have a different physical state
than the reactants.
• The total mass of the reactants must equal the total
mass of the products.
• The reactants must contain more complex molecules
than the products do.
• The density of the reactants must equal the density
of the products.
This equation supports the law of conservation
of mass because:
the total number of hydrogen and oxygen atoms in
the reactants and products is twelve.
b. the mass of hydrogen and oxygen in the reactants
is equal to the mass of the water in the product.
c. atoms of the elements hydrogen and oxygen are in
the reactants and also in the products.
d. atoms of the elements hydrogen and oxygen react
to form molecules of the compound water.
a.

Which of the following is true about the mass of the
reactants and the products?
The mass of the natural gas and oxygen will be
less than the mass of the water and carbon
dioxide.
b. The mass of the natural gas and oxygen will be
greater than the mass of the water and carbon
dioxide.
c. The mass of the natural gas and oxygen will be
equal to the mass of the water and carbon dioxide.
d. The mass of the natural gas and oxygen will be
destroyed to make water and carbon dioxide.
a.
 Identify
the balanced equation that supports
the law of conservation of mass.
a. H2 + O2
b. 2H2 + 2O2


c. 2H2 + O2

d. H2 + 2O2

2H2O
2H2O
2H2O
2H2O

If all the reactants in a chemical reaction are
completely used, which of the following
statements accurately describes the relationship
between the reactants and the products?
The products must have different physical state than the
reactants.
b. The total mass of the reactants must equal the total
mass of the products.
c. The reactants must contain more complex molecules
than the products do.
d. The density of the reactants must equal the density of
the products.
a.
 When
a 1-kilogram log was burned, 0.05
kilogram of ash was produced. The mass of
the ash is less than the mass of the log
because —
a. wind carried away some matter before it burned.
b. some matter was converted to gases that were
released.
c. combustion changed some matter into energy
d. some matter was decomposed by organisms in the
soil
 The
total mass of reactants in a chemical
reaction must be______ the total mass of
the product.
a. less than
b. more than
c. equal to
d. double
A
mixture of baking soda is prepared in
water. The mass of this mixture is 225g.
The original mass of baking soda was
50g. What is the original mass of water to
which the baking soda was added?
• 50g
• 175g
• 225g
• 275g