1. Descriptive Abbreviations
(s) Solid
(l) Liquid
(g) Gas
(aq) Aqueous
dissolved in water
How do we know the states of matter in a reaction?
Word problem tells us
States of matter from the periodic table
Common knowledge
Episode 605

2. Determining State at Room Temperature
All metals are solids except for mercury, which is a liquid.
Most non-metals are gases with these exceptions:
Liquid – bromine
Solids – carbon, phosphorus, sulfur, selenium, tellurium, and astatine
All metalloids are solids
Ionic compounds are solid, unless told otherwise.
Covalent compounds are liquid, unless told otherwise.
Episode 605

3. When heated, solid mercury (II) oxide yields mercury and oxygen gas.
Write the balanced chemical equation including the descriptive abbreviations for the state of matter.
2 HgO(s) → 2 Hg(l) + O2(g)
Episode 605

4. Classifying Reactions
Synthesis
Two or more substances combine to form a more complex substance
A + B  AB
Fe(s) + S(s)  FeS(s)
H20(l) + SO3(g)  H2SO4(aq)
(acid rain)
Episode 605

5. Classifying Reactions
Decomposition
A single substance is broken down into two or more simpler substances
AB  A + B
H2O (l)  H2(g) + O2(g)
2HgO  2Hg(l) + O2↑
Episode 605

6. Classifying Reactions
Single Replacement
A free element replaces a less reactive element in a compound
A + BY  AY + B
Zn (s) + 2HCl(aq)  ZnCl2(aq) + H2(g)
2Al(s) + 3CuCl2(aq)  2AlCl3(aq) + 3Cu(s)
Cu(s) + MgCl2(aq) 
Activity Series: an arrangement of elements in the order of their tendency to react
NR (no reaction)
Episode 605

7. Activity Series Decreasing activity
Lithium Potassium Barium Calcium Sodium Magnesium Aluminum Manganese Zinc Chromium Nickel Tin Lead (Hydrogen) Copper Mercury Silver Gold
Decreasing activity
Episode 605

8. Classifying Reactions
Double Replacement
The elements of a reacting compounds replace each other
Normally takes place in an aqueous solution
Also called metathesis reaction
AX + BY  AY + BX
2KI(aq) + Pb(NO3)2(aq)  PBI2(s) + KNO3(g)
Precipitate
An insoluble solid
May be represented in an equation by (s) or ↓
NaCl(aq) + AgNO3(aq)  NaNO3(aq) + AgCl ↓
Episode 605

9. Classifying Reactions
Combustion
Involves the reaction of a substance with oxygen
Often called burning
The complete combustion of a hydrocarbon produces CO2 and H2O
CxHy + O2  CO2 + H20
C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(l)
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
Episode 605