Bell Work 11-30-15
• What do you use to convert grams to
moles or moles to grams?
• What do you use to convert
particles(atoms, molecules, units) to moles
or vice versa?
• If I am changing from grams to particles
what do I need to do?
• Convert 184g of PbI2 to particles.
Extra Credit-Memes!
• Create a meme that is related to chemistry.
• To create a meme, go to a meme generator
website. Choose a blank meme and add your own
text.
• After you have created a meme save the image.
Either email me or print the image.
• You need to include 2-3 sentences describing the
science behind your meme and why it is funny
and clever.
• DUE BY MONDAY, DECEMBER 7
Unit 6: Chemical Reactions
What are indications that a
chemical reactions has
happened?
Bell Work 12-1-15
• List 5 things that would indicate a
chemical reaction has occurred.
Indicators of chemical reactions
Emission of light or heat
Formation of a gas
Formation of a precipitate
Color change
Emission of odor
All chemical reactions:
Have two parts
1. Reactants - the substances you start with
2. Products- the substances you end up with
The reactants turn into the products
Reactants  Products
Describing Chemical Reactions
Can be described several ways:
1. In a sentence
Copper reacts with chlorine to form
copper (II) chloride.
2. In a word equation
Copper + chlorine  copper (II) chloride
Cu + Cl2  CuCl2
Symbols used in equations
(s) after the formula –solid Cu(s)
(g) after the formula –gas H2 (g)
(l) after the formula -liquid H2O(l)
(aq) after the formula - dissolved in water, an
aqueous solution. CaCl2 (aq)
Cu(s) + Cl2(g)  CuCl2(aq)
Symbols used in equations
indicates a reversible reaction
supplied to the reaction
shows that heat is
Diatomic elements
There are 7 elements that never want to be
alone.
They form diatomic molecules, in gas state.
H2 , N2 , O2 , F2 , Cl2 , Br2 , and I2
Law of Conservation of Mass
In a chemical reaction, matter is neither
created nor destroyed.
Atoms won’t change their identity (e.g. a
Carbon atom can’t become an Iron atom)
This means that you have to have the same
number of each type of atom on each side of
the chemical equation.
Law of Conservation of Mass
• Atoms cannot be created or destroyed!
• Total mass stays the same.
• The atoms are rearranged to form new materials.
Balancing Equations
We can see that the equation, does not follow
the Law of Conservation of Mass
C2 + O2  CO2
We can see that on the product side there are
two carbon atoms, but on the reactant side
there is only one. This cannot possibly
happen, as mass cannot be destroyed
Balancing Equations
• To balance chemical equations follow these
basic steps
1. Perform an atom inventory—count how many
of each element you have on each side of the
arrow.
2. Identify your problem areas
3. Begin adjusting the coefficients of the
equation to balance the equation. You
cannot change the subscripts, only the
coefficients!
Balancing Equations
C2 + O2  CO2
1. Atom inventory
2. Identify Problems
3. Fix Problems
WARNING!
Don’t mess with the insides of polyatomic
ions – put a square around them, or label
them as X – treat the WHOLE polyatomic ion
as though it were an element!
Don’t ever play around with subscripts
(those little numbers that tell you how many
atoms are in a molecule)
e.g.
C6H22O11
7.
H2 + Cl2  HCl
1H2 + 1Cl2  2HCl
8.
CdCO3  CdO + CO2
Already Balanced 
4.
Li + FeBr2  LiBr + Fe
2Li + 1FeBr2  2LiBr + 1Fe
3.
KClO3  KCl + O2
2KClO3  2KCl + 3O2
5.
NaOH + FeCl3  NaCl + Fe(OH)3
3NaOH + 1FeCl3  3NaCl + 1Fe(OH)3
2.
Na + H2O  NaOH + H2
2Na + 2H2O  2NaOH + 1H2
6.
Ca2Br2 + NaCO3  CaCO3 + NaBr
1Ca2Br2 + 2NaCO3  2CaCO3 + 2NaBr
Bell Work 12-6-15
Balance the following equations:
1.___Al2(SO4)3 +___ Ca(OH)2 →__ Al(OH)3 +
__ CaSO4
2. ___Cr +___ O2 →____ Cr2O3
Types of Reactions
1.
2.
3.
4.
5.
Synthesis reactions
Decomposition reactions
Single displacement reactions
Double displacement reactions
Combustion reactions
1. Synthesis
Example C + O2
C + O O
General:

O C O
A + B  AB
Definition: multiple reactants combine to
form a single product
http://www.youtube.com/watch?v=uCwHzTsx5yY
2. Decomposition
Example: NaCl
Cl Na

General:
Cl
+
Na
AB  A + B
Definition: breakdown of one molecule into
elements or simple compounds
http://www.youtube.com/watch?v=ImWpJienMRA
3. Single
Displacement/Replacement
Example: Zn + CuCl2
Cu
Cl
+
Cl
General:
Zn

Zn
Cl
+
Cu
Cl
AB + C  AC + B
Definition: an element or ion is replaced
by another in a compound
4. Double displacement
Example: MgO + CaS
Mg
+
Ca
O
General:
S

Mg
S
+
Ca
O
AB + CD  AD + CB
Definition: two elements or ions are
replaced by another in multiple compounds
5. Combustion Reactions
Definition: a
hydrocarbon reacts
with oxygen gas.
This is also called
burning!!!
In general:
CxHy + O2  CO2 + H2O
Products are ALWAYS
carbon dioxide and
water.
Bell Work 12-8-15
1.Balance the equation
2. What type of reaction?
1. _____ Ca + _____ O2  _____ CaO
Reaction: _______________
2. _____ Cu2O + _____ C  _____ Cu + _____ CO2
Reaction: _______________
3. _____ Na + _____ MgF2  _____ NaF + _____ Mg
Reaction: _______________
4. _____ Na + _____ HCl  _____ H2 + _____ NaCl
Reaction: _______________
5. _____ Cl2 + _____ KI  _____ KCl + _____ I2
Reaction: _______________
Activity Series.
Elements will replace elements below them in
single rep. reactions.
K
Ca
Na
Mg
Al
Zn
Fe
Ni
Pb
H
Cu
Ag
Solubility Table
Ion
NO3–
ClO4–
Solubility
soluble
soluble
Exceptions
none
none
Cl–
soluble
I–
soluble
SO42-
soluble
CO32PO43-
insoluble
insoluble
except Ag+, Hg22+, *Pb2+
except Ag+, Hg22+, *Pb2+
except Ca2+, Ba2+, Sr2+, Hg2+, Pb2+,
Ag+
except Group IA and NH4+
except Group IA and NH4+
OH–
insoluble
except Group IA, *Ca2+, Ba2+, Sr2+
S2-
insoluble
except Group IA, IIA and NH4+
Na+
K+
NH4+
soluble
soluble
soluble
none
none
none
AgNO3(aq)
CuSO4(aq)
Li3N
NH4NO3