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CHAPTER 8
REACTIONS IN AQUEOUS SOLUTIONS
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Synthesis Reactions (Compositions Reactions): A + X AX
examples
• Fe + S FeS
• 2 Ca + O2 2CaO
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONSDecomposition Reactions -- 6 TYPES (memorize)
1. metallic carbonate metallic oxide + carbon dioxide
• CaCO3 CaO + CO2 (g)
• Na2CO3 Na2O + CO2 (g)
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Decomposition Reactions -- (continued)
2. metallic hydroxide metallic oxide + water
• Mg(OH) 2 MgO + H2O (g)
• 2NaOH Na2O + H2O (g)
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Decomposition Reactions -- (continued)
3. metallic chlorate metallic chloride + oxygen
• 2 KClO3 2 KCl + 3 O2
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Decomposition Reactions -- (continued)
4. acid nonmetallic oxide + water
• H2CO3 CO2 (g) + H2O
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Decomposition Reactions -- (continued)
5. Some oxides decompose
• 2 HgO 2 Hg + O2 (g)
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Decomposition Reactions -- (continued)
6. electrolysis – separation by electric current
• 2 NaCl 2 Na + Cl2 (g)
• 2 H2O 2 H2 + O2 (g)
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Single – Replacement Reactions FOUR TYPES
1. Metal in a compound replaced by more active metal
• Zn + CuSO4 ZnSO4 + Cu
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Single – Replacement Reactions FOUR TYPES
2. Hydrogen in water replaced by active metal
• 2 Na + 2H2O 2NaOH + H2
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Single – Replacement Reactions FOUR TYPES
3. Hydrogen in acid replaced by metal
Zn + H2SO4 ZnSO4 + H2 (g)
metal + acid metallic compound + hydrogen gas
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Single – Replacement Reactions FOUR TYPES
4. Halogen replacing halogen
F2 + 2KCl KF + Cl2
more active halogen (F) replaces less active (Cl)
activity decreases down group VII (17)
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Double – Replacement Reactions
OR Ionic reactions:
AX + BY AY + BX
NaCl + AgNO3 NaNO3 + AgCl
CuO + H2SO4 CuSO4 + H2O
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Combustion Reactions
substance reacts with oxygen to release heat and light energy
2 H2 + O2 H2O
C3H8 (g) + 5O2 3CO2 (g) + 4H2O
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Combustion Reactions
Assignment: pg
CHEMICAL EQUATIONS AND REACTIONS
Common Formulas (MEMORIZE)
Free Elements often exist as single atoms
(examples: Ag, Cu, C, S, etc)
• are written as such in equations
C + O2 CO2
2 Ag + 2 HNO3 2 AgNO3 + H2
CHEMICAL EQUATIONS AND REACTIONS
Common Formulas (MEMORIZE)
Noble Gases always exist in free state as monatomic molecules (and almost never react)
(He, Ne, Ar, Kr, Xe, Rn)
CHEMICAL EQUATIONS AND REACTIONS
TYPES OF CHEMICAL REACTIONS
Common Formulas (MEMORIZE)
Eight elements exist as DIATOMIC MOLECUES in the free state
• gases at room temperature: N2, O2, H2, F2, Cl2
• liquid (@ r.t.): Br2
• solid (@ r.t.): I2 & At2
• written as such in equations
– Br2 + 2KI 2KBr + I2
– S + O2 SO2
CHEMICAL EQUATIONS AND REACTIONS
ACTIVITY SERIES OF THE ELEMENTS• A list of elements organized according to the
ease with which the elements undergo certain chemical reactions.
• Determined by the single replacement reaction
• Describes reactivity and ability to replace an ion in a compound
• Charts
s:\Chemistry\resources\reactivity series chart.doc
S:\Chemistry\resources\The Reactivity Series.doc
CHEMICAL EQUATIONS AND REACTIONS
Common Formulas (MEMORIZE)
• ammonia: NH3
• steam: H2O
• water: H2O
• ice: H2O
• hydrogen peroxide: H2O2