Download CHEMICAL REACTIONS Chapter 4

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CHEMICAL REACTIONS
Chapter 4
Reactants: Zn + I2
Product: Zn I2
Chemical Equations
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4 Al(s) + 3 O2(g) ---> 2 Al2O3(s)
This equation means
4 Al atoms + 3 O2 molecules ------>
2 formula units of Al2O3
4 moles of Al + 3 moles of O2 ---->
2 moles of Al2O3
Chemical Equations
Depict the kind of reactants and
products and their relative amounts in
a reaction.
4 Al(s) + 3 O2(g) ---> 2 Al2O3(s)
The numbers in the front are called
stoichiometric coefficients
The letters (s), (g), and (l) are the physical
states of compounds.
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Chemical Equations
Because of the principle of the
Lavoisier, 1788
conservation of matter,
an equation must be
balanced.
It must have the same
number of atoms of the
same kind on both sides.
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Chemical Equations
•The Law of the Conservation of Matter
• The amount of
matter in a system
does not change:
the same atoms
are present in a
reaction at the
beginning and at
the end.
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Balancing
Equations
___ Al(s) + ___ Br2(liq) ---> ___ Al2Br6(s)
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Balancing
Equations
____C3H8(g) + _____ O2(g) ---->
_____CO2(g) + _____ H2O(g)
____B4H10(g) + _____ O2(g) ---->
___ B2O3(g) + _____ H2O(g)
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STOICHIOMETRY
- the study of the
quantitative
aspects of
chemical
reactions.
STOICHIOMETRY
It rests on the principle of the conservation of
matter.
2 Al(s) + 3 Br2(liq) ------> Al2Br6(s)
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STOICHIOMETRY
CALCULATIONS
Stoichiometric
factor
Moles
reactant
Moles
product
Zn + 2 HCl 
ZnCl2+
H2
Given 7 mol of Zn,
1. How many moles of acid are
need to react all the zinc?
2. How many moles of hydrogen
gas are produced?
3.How many moles of ZnCl2 are
produced?
2 KClO3  2 KCl + 3 O2
Given you need to produce
21 moles of oxygen gas:
1. How many moles of KClO3
do you need to start with?
2. How many moles of KCl
are produced?
2 2H6+ 7 O2  4 CO2+ 6 H2O
__C
Given 10 moles of C2H6 :
1. How many mole of oxygen gas
do you need to react all the
ethane?
2. How many moles of water are
produced?
3. How many moles of carbon
dioxide will be produced?