Chapter 8 Section 2
**Remember H O N Cℓ Br I F
Types of Chemical Reactions
1) Combination/Synthesis Reaction
-two or more substances combine to form a
single substance
reactants- two elements or two compounds
products- always a compound
ex2K + Cℓ2 → 2KCℓ
exSO2 + H2O → H2SO3
Try these!! Don’t forget to balance!!
a) aluminum + oxygen →
Aℓ + O2 →
Aℓ + O2 → Aℓ2O3
b) beryllium + oxygen →
Be + O2 →
Be + O2 → BeO
c) strontium + iodine →
Sr + I2 →
Sr + I2 → SrI2
d) magnesium + nitrogen →
Mg + N2 →
Mg + N2 → Mg3N2
2) Decomposition Reaction
-one compound breaks down or decomposes into
two simpler compounds
-the reverse of synthesis
ex- 2H2O → 2H2 + O2
Try these!!
a) lead(IV) oxide →
PbO2 →
PbO2 → Pb + O2
b) hydrogen iodide →
HI →
HI → H2 + I2
c) hydrogen bromide →
HBr →
HBr → H2 + Br2
d) sodium chloride →
NaCℓ →
NaCℓ → Na + Cℓ2
3) Single-Replacement Reactions
-one element replaces a second element in a
compound
ex- 2K + CaO → K2O + Ca
-whether one metal will replace another metal is
determined by reactivity of the metal
activity series of metals- lists metals in order of
decreasing reactivity
**Page 217
-a metal will replace another metal listed
below it in the table
ex- Mg + Zn(NO3)2 →
*is Mg above Zn on the reactivity series?
Mg + Zn(NO3)2 → Mg(NO3)2 + Zn
ex- Mg + Ag2SO4 →
Mg + Ag2SO4 → MgSO4 + Ag
ex- Mg + LiNO3 →
-lithium is above magnesium
Mg + LiNO3 → no reaction (NR)
-Halogens can replace each other in singlereplacement reactions
-Reactivity decreases as you go down the
halogen group
Try These!!
a) zinc + hydrogen sulfate →
Zn + H2SO4 →
Zn + H2SO4 → H2 + ZnSO4
b) chlorine + sodium bromide →
Cℓ2 + NaBr →
Cℓ2 + NaBr → Br2 + NaCℓ
c) zinc + sodium nitrate →
Zn + NaNO3 → no reaction
d) iron(II) + lead(II) nitrate →
Fe + Pb(NO3)2 →
Fe + Pb(NO3)2 → Pb + Fe(NO3)2
e) chlorine + sodium iodide →
Cℓ2 + NaI →
Cℓ2 + NaI → I2 + NaCℓ
4) Double-Replacement Reactions
-involve an exchange of cations between two
reacting compounds
ex- BaCℓ2 + K2CO3 → BaCO3 + 2KCℓ
ex- FeS + 2HCℓ → H2S + FeCℓ2
Try These!!
a) sodium hydroxide + iron(III) nitrate →
NaOH + Fe(NO3) 3 →
NaOH + Fe(NO3) 3 → NaNO3 + Fe(OH)3
b) barium nitrate + hydrogen phosphate →
Ba(NO3) 2 + H3PO 4 →
Ba(NO3) 2 + H3PO 4 → Ba3(PO4) 2 + HNO3
c) potassium hydroxide+hydrogen phosphate →
KOH + H3PO4 →
KOH + H3PO4 → K3PO4 + H2O
d) hydrogen sulfate + aluminum hydroxide →
H2SO4 + Aℓ(OH)3 →
H2SO4 + Aℓ(OH)3 → Aℓ2(SO4)3 + H2O
5) Combustion Reaction
-hydrocarbon combined with oxygen to produce
carbon dioxide and water
ex- C6H6 + O2 → CO2 + H2O
-to balance:
*always begin with a 2 in front of hydrocarbon
*when done, if can divide by 2 do so
2C6H6 + 15O2 → 12CO2 + 6H2O
Try These!!
a) C14H26 + O2 →
2C14H26 + 41O2 → 28CO2 + 26H2O
b) C8H12 + O2 →
2C8H12 + 22O2 → 16CO2 + 12H2O
C8H12 + 11O2 → 8CO2 + 6H2O
Summary of Reactions
1) Combination/Synthesis
R + S → RS
2) Decomposition Reaction
RS → R + S
3) Single-Replacement Reaction
T + RS → R + TS
4) Double-Replacement Reaction
RS + TU → RU + TS
5) Combustion Reaction
CxHy + O2 → CO2 + H2O