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