Chemical Equations and Reactions Describing Chemical Reactions.
Types of Chemical Reactions. There are only five (5) different types of chemical reactions: 1)...
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Transcript of Types of Chemical Reactions. There are only five (5) different types of chemical reactions: 1)...
Types of Chemical Reactions There are only five (5) different types of
chemical reactions:1) Double Replacement2) Single Replacement3) Synthesis/Formation4) Decomposition5) Combustion
Reaction Type 1 – Double Replacement
Occur between two ionic compoundsDoes not happen with covalent compounds
Involves an exchange of cations (positive ions)
The cation of one compound trades places with the cation of another compound to form two new compounds
Double Replacement - Characteristics
occur in solution when the compounds are in an aqueous state (aq)reactants are either aqueous to begin with,
or solid compounds dissolved in water to form an aqueous solution of ions
in order to drive the reaction, one of the products must be removed from the aqueous solution
this can occur via one of three ways:
Double Replacement - Characteristics
1) Formation of a precipitate (an insoluble solid forms in the solution)
i.e.:
AgNO3 (aq) + NaCl (aq) = NaNO3 (aq) + AgCl (s)
Solid silver chloride is formed as precipitate and comes out of the solution
Double Replacement - Characteristics
2) Formation of a gas i.e.:
FeS (aq) + 2HCl (aq) = H2S (g) + FeCl2 (aq)
Hydrogen sulfide gas is formed and comes out of the solution
Double Replacement - Characteristics
3) Water is formed when a hydrogen cation unites with a hydroxide anion
i.e.:
NaOH (aq) + HCl (aq) = HOH (l) + NaCl (aq)
Water (HOH) is formed and comes out
of the solution
Identifying a Double Replacement Reaction
Double replacement reactions always have two ionic compounds on the REACTANTS side AND on the PRODUCTS side of an equation
*Two compounds react to form two new compounds*AB + CD CB + AD
○ A & C are cations, B & D are anions○ A & C switch places
Single Replacement Reactions: Characteristics: Atom (s) of a lone element replace the
atom (s) of an element in a compoundMetals replace metals (or cations replace
cations)Non-metals replace non-metals (or anions
replace anions)
Single Replacement Reactions: Characteristics: Metal Cation Replacement:
For the reaction:
A + BC B + AC
A and B are cationsA “replaces” B in the compound
Single Replacement Reactions: Characteristics: Non-metal Anion Replacement:
For the reaction:
D + EF ED + F
D & F are anionsD “replaces” F in the compoundNon metal replacements usually involve
halogens
Restrictions on Single Replacement Reactions Activity Series:
A characteristic of metals and halogens referring to their reactivity
Determines whether or not a single replacement reaction will occur or not
Metals: on page 155 (table 7-2) there is an activity series of metals arranged in order of decreasing activity
Non-metals (Halogens) : as you move down the group on the periodic table activity decreases
Restrictions on Single Replacement Reactions A single replacement reaction WILL
NOT OCCUR if the reactivity of the pure element reactant is less than that of the compound reactanti.e.:
Sn (s) + NaNO3 (aq)
no reaction b/c tin is less reactive than sodium
Restrictions on Single Replacement Reactions A single replacement reaction WILL
OCCUR if the reactivity of the pure element reactant is greater than that of the compound reactanti.e.:
Zn (s) + H2SO4 (aq) ZnSO4 (aq) + H2 (g)
Reaction occurs because the reactivity of zinc is higher than hydrogen
Identifying Single Replacement Reactions Single replacement reactions ALWAYS
have 1 lone element and 1 compound on the reactants side and the products side
Reactants will always be:1 lone element + 1 compound
Products will always be:1 lone element + 1 compound
Reaction Type #3 - Decomposition Occurs when a single compound breaks
down into two or more components Energy is required for them to occur Reactants will always be:
1 compound Products will always be:
ALWAYS more products than reactants2 components (either compounds or elements)
i.e.: AB A + B
Decomposition Example: One unit breaks
down into its component parts
i.e. – The marriage of Brad Pitt and Jennifer Aniston breaks into the single Brad Pitt and the single Jennifer Aniston
Reaction Type #4 – Synthesis/Formation Occurs when two or more components
come together to form one compound Energy is released when these reactions
occur Reactants will always be:
ALWAYS more reactants than products!2 or more components (either elements or
compounds) Products will always be:
1 single compound i.e.:
A + B AB
Synthesis/Formation Example
Two individual components coming together to form one unit
i.e. – single Robert Pattinson and a single Kristen Stewart come together to form a totally awesome Twilight couple OMG OMG LOL ECLIPSE! LIKE TOTALLY AWESOME!
Special Cases for Decomposition & Synthesis/Formation Reactions Decomposition and Synthesis/Formation
Reactions are opposite processes (duh) Special Case #1:
A non metal oxide + water combine to form an acid ○ i.e.: SO3 + H2O H2SO4
AND an acid will decompose to form a non-metal oxide + water○ i.e.: H2SO4 SO3 + H2O
Special Cases for Decomposition & Synthesis/Formation Reactions Special Case #2
A metal oxide + water combine to form a metal hydroxide ○ i.e.: CaO + H2O Ca(OH)2
A metal hydroxide will decompose into a metal oxide + water○ i.e.: Ca(OH)2 CaO + H2O
Special Cases for Decomposition & Synthesis/Formation Reactions Special Case #3:
All carbonates decompose into carbon dioxide and an oxide
i.e.: CaCO3 CaO + CO2
Vice versa for synthesis/formation reactions
Special Case #4:All chlorates decompose into oxygen and a
binary salti.e.: KClO3 KCl + O2
Vice versa for synthesis/formation reactions