General Chemistry Zumdahl Chapter 7 Notes

General Chemistry
Zumdahl Chapter 7 Notes
Chemical Reactions
Week of 1/26/15, Expected test date, Tuesday 2/3/15
Standard: HS-PS1-7 Use mathematical
representations to support the claim that
atoms, and therefore mass, are
conserved during a chemical reaction.
Where do we see chemical reactions?(1)
Everywhere! Cars driving, hair growing,
clothes being made, etc…
7.1 Evidence for a Chemical
Reaction p. 193 of book
Most chemical reactions give a visual
signal when they occur.
 What are some examples of these visual
Color change
Precipitate (solid) forms
Gas is formed (bubbles)
A flame forms
7.2 Chemical Equations, p. 195
◦ Chemical reaction(3): Atoms of different
compounds are rearranged forming new
◦ Chemical equation(4): A visual representation
of a chemical reaction
◦ Reactant(5): Chemicals before the reaction
◦ Products(6): Chemicals after the reaction
7.2 Chemical Equations
What are the abbreviations for
Solid (7): (s)
Liquid (8): (l)
Gas (9): (g)
Dissolved in water or aqueous (10): (aq)
7.3 Balancing Chemical Equations,
p. 200
It is important to understand that in a
chemical reaction atoms are neither
created nor destroyed.
◦ There are the same amount of each atom on
the reactant side as there are on the product
7.3 Balancing Chemical Equations
The burning of methane gas produces
carbon dioxide and water
CH4(g) + O2(g)  CO2(g) + H2O(l)
What is wrong with this?(11)
Not balanced!
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
7.3 Balancing Chemical Equations
The chemical formation of water
 H2(g) + O2(g)  H2O(l)
 What is wrong with this?(12) Not
2H2(g) + O2(g)  2 H2O(l)
 Define coefficient(13): The number of
compounds that is needed to make
equation balanced.
7.3 Balancing Chemical Equations
Balance (14)
C2H5OH(l) + O2(g)  CO2(g) + H2O(l)
C2H5OH(l) + 3O2(g)  2CO2(g) + 3H2O(l)
N2(g)+H2(g) NH3(g)
N2(g)+3H2(g)2 NH3(g)
O2(g)  O3(g)
3O2(g)  2O3(g)

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