Name_________________________________________________ Date ___________________Per_____
Reaction Types
A. Synthesis Reactions (Composition Reactions)
2 or more substances react to form a larger compound. (By products may form)
A + X AX
1. Reactions of elements with oxygen and sulfur
Mg(s) + O2(g)  2MgO(s)
4 Fe(s) + 3 O2(g)  2 Fe2O3(s)
A or B = metal, compounds, or cations
X or Y =nonmetals, compounds, or anions
8Mg(s)+S8(s)  8BaS(s)
2. Reactions of metals with halogens
Ca(s)+Br2(l)  CaBr2(s)
3. Reactions with oxides
CaO(s)+H2O(l)  Ca(OH)2(s)
SO3 (g) + H2O (l)  H2SO4 (aq)
B. Decomposition Reactions
One substance reacts to form smaller compounds.
AX  A + X
1. Electrolysis
electricity
2H2O (l)  2H2(g) + O2(g)
2. Heating of some oxides
T
2HgO(s)  2 Hg(s)+ O2(g)
3. Metallic carbonates, when heated, yield metallic oxides and carbon dioxide.
T
CaCO3(s)  CaO(s) + CO2(g)
4. Metallic hydroxides, when heated, yield metallic oxides and water.
T
2NaOH(l)  Na2O(s) + H2O(l)
5. Metallic chlorates, when heated, form metallic chlorides and oxygen.
T
2KClO3(s)  2KCl(s) + 3O2(g)
6. Certain oxy-acids decompose into nonmetallic oxides and water.
T
H2CO3(aq)  CO2(g) + H2O(l)
C. Single- Displacement Reactions
An element exchanges places with an ion of a compound to form a different compound and element.
A + BX AX + B
Y + BX BY + X
1. Displacement of a metal in a compound by a more active metal.
2Al(s) + 3Fe(NO3)2(aq) 3Fe(s) + 2Al(NO3)3 (aq)
2. Displacement of hydrogen in water and steam by a more active metal.
2Na(s) + 2H2O(l) 2NaOH(aq) + H2 (g)
3. Displacement of hydrogen in an acid by a metal.
Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)
4. Displacement of halogens by more active halogens.
Cl2(g) + 2NaBr(aq) 2NaCl(aq) + Br2 (l)
D. Double- Displacement Reaction
The ions from two compounds exchange places in aqueous solutions to from two different compounds.
AX + BY  AY + BX
1. Formation of a precipitate
2KI(s) + Pb(NO3)2(aq)PbI2(s) + 2KNO3(aq)
2. Formation of a gas
FeS(s) + 2HCl(aq)  H2S(g) + FeCl2(aq)
3. Formation of water (acid-base neutralization)
HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
E. Combustion
A compound reacts with oxygen releasing large amounts of energy in the form of heat and light. The
combustion of hydrocarbons are one example, but others do exist.
C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g)
Does a single displacement reaction occur?
Use the activity series to identify if it will.
Element
Li
Rb
K
Ba
Ca
Na
Mg
Al
Mn
Zn
Cr
Fe
Reactivity
React with cold water and
acids replacing H
A reaction will only occur if an element is
lower than the original element in the
starting compound.
React with acids or steam, but
usually not liquid water, to
replace hydrogen
Ni
Sn
Pb
All react with acids, but not
water, to replace hydrogen
H2
Cu
Hg
Ag
Pt
Au
F2
Cl2
Br2
I2
All react with oxygen to from
oxides
Mostly unreactive
Listed from most to least
reactive
For example Mg can replace Fe in a reaction
but Fe cannot replace Mg.