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CHEMICAL REACTION
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MAIN POINTS
Chemical reactions are represented by chemical
equations
Chemical equations are balanced to show the
same number of atoms of each elemen on each
side
The law of conservation of mass says that atoms
wont be created or destroyed in a chemical
reaction. That is why you have to balance
chemical equations
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CHEMICAL REACTIONS ARE EVERYWHERE
Cooking Respiration
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Auto Fuel
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How do you know when a chemical reaction takes
place?
Color Change Precipitate Formation
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How do you know when a
chemical reaction takes place?
Gas Formation Odor
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How do you know when a
chemical reaction takes
place? Temperature
Change
Change in Acidity
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Representing Chemical
Reactions
Chemists observe chemical reactions and have come up with a way to
represent or model what is
happening.
Making NaCl
Solid Sodium combines with Chlorine gas to make solid Sodium Chloride:
2Na (s) + Cl2 (g) 2NaCl
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PRACTICE PROBLEMS
Describe each reaction:
Calcium and fluorine react to form calcium floride
Barium chloride and hydrogen sulfate react to form
hydrogen chloride and barium sulfate
Calcium carbonate, carbon dioxide, and water react
to form calcium hydrogen carbonate
Hydrogen peroxide reacts to form water and oxygen
Sulfur dioxide and oxygen react to form sulfur
trioxide
HCl + Na2SO3 nAcL + H2O +SO2
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TYPES OF REACTIONS
Combination reaction
A + B AB
Decomposition reactions
AB A + B
Displacement reactions
AB + C AC + B
Metathesis reactions (double-replacement
reactions)
AB + CD AD + CB
Combustion reactions (reaction with oxygen)
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COMBINATION REACTION
Is also refer to as a synthesis reaction
It is chemical change in which two or more
substances react to form a new singular subtance
The product is a compound in this form of
reaction
You can tell this reaction has occurred because
on the reactant side there are multiple subtances,
while on the product side there is only one
product
A + B AB
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DECOMPOSITION REACTIONS
This is a chemical change where a single
compound (the reactant) breaks down into two or
more simpler products
This type of reaction is easily identifiable,
because
It is the exact opposite of synthesis, if you know obe,
you know them both
There is always one reactant, if you see one reactant,
thats a compound of several products, a decomposition reaction occured
AB A + B
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SINGLE-REPLACEMENT REACTIONS
A chemical change where one element replaces a
second element in a compound
It is identifiable by its symmetry. On the
reactant side there is a single element and a
compound, as there is on the product side
No reaction will occur if the most reactive
element is already in the compound
AB + C AC + B
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DOUBLE-REPLACEMENT REACTIONS
A chemical change where there is an exchange of
positive ions between two compounds
May also be called double-displacement reactions
Generally take place in aqueous solution
Often produce a precipitate, a gas, or molecular
compound (water)
AB + CD AD + CB
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COMBUSTION REACTION
A chemical change where an element or a
compound reacts with oxygen
This will often yield energy in the form of the het
and light
Oxygen is always going to be on the reactant side
CH4 + O2 CO2 + H2O
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PRACTICE PROBLEM
What type of reaction is this?
AgNO3 + KCl AgCl + KNO3
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Fill in the blank
CH4 + ________ CO2 + H2O
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What Type Of Reaction Has Occurred Here?
Br2 + NaI NaBr + I2
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What Type Of Reaction Will The Following Be
Br2 + NaCl ____________________________
Zn + H2SO4 ZnSO4 + H2
KCl K + Cl
KOH + H2SO4 K2SO4 + H2O
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NH3(g) + 2O2(g) HNO3(aq) + H2O(l)
CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O(l) + CO2(g)
N2H4(l) + N2O4(l) N2(g) + H2O(l)
Zn(NO3)2(aq) + Na3PO4(aq) Zn3(PO4)2(s) + NaNO3(aq)
P4(s) + Cl2(g) PCl3(l)
PbO(s) + NH3(g) Pb(s) + N2(g) + H2O(l)
P4O10(s) + H2O(l) H3PO4(aq)
Mn(s) + CrCl3(aq) MnCl2(aq) + Cr(s)
