Predicting Reactions, Writing, and Balancing Chemical Equations
When assigning oxidation numbers to elements in a compound the overall value will add up to
0
barium oxide → barium + oxygen
2 BaO → 2 Ba + O₂
ethane + oxygen → carbon dioxide + water
2 C₂H₆ + 7 O₂ → 4 CO₂ + 6 H₂O
synthesis reaction
2 single elements bond to form a compound.
hydrogen + nitrogen → NH₃
3 H₂ + N₂ → 2 NH₃
aluminum sulfate + calcium hydroxide → aluminum hydroxide + calcium sulfate
Al₂(SO₄)₃ + 3 Ca(OH)₂ → 2 Al(OH)₃ + 3 CaSO₄
barium chloride + sulfuric acid → barium sulfate + hydrochloric acid
BaCl₂ + H₂SO₄ → BaSO₄ + 2 HCl
carbon + water → carbon monoxide + hydrogen
C + H₂O → CO + H₂
calcium oxide + water → calcium hydroxide
CaO + H₂O → Ca(OH)₂
hydrochloric acid + sodium hydroxide → sodium chloride + water
HCl + NaOH → NaCl + H₂O
hydrogen + chlorine → HCl
H₂ + Cl₂ → 2 HCl
phosphorus + oxygen → diphosphorus pentoxide
P₄ + 5 O₂ → 2 P₂O₅
Reduction
Shows a gain of electrons; the oxidation numbers will become more negative; electrons are shown on the reactant side.
Oxidation
Shows a loss of electrons; the oxidation numbers will become more positive; electrons are shown on the product side.
sulfur + oxygen → sulfur dioxide
S₈ + 8 O₂ → 8 SO₂
special trend for synthesis reactions
When Fe, Cu, Pb, Sn bond with FON use higher charge for metal ion. When Fe, Cu, Pb, Sn bond to any other nonmetal use lower charge.
zinc + sulfuric acid → zinc sulfate + hydrogen
Zn + H₂SO₄ → ZnSO₄ + H₂
When predicting single replacement reactions you must use the
activity series
hydrocarbon and oxygen produce
carbon dioxide and water
metal chlorates decompose to produce
metal chloride and oxygen
metal carbonates decompose to produce
metal oxide and carbon dioxide
metal hydroxides decompose to procude
metal oxide and water
When predicting double replacement reactions you must use the
solubility chart to predict if the ions will form a solid precipitate (which is a sign of a reaction) or dissolve in the solution (which would be no reaction).
When assigning oxidation numbers to elements in a polyatomic ion the overall value will add up to
the charge of the ion
metal oxides when heated
will decompose into a metal and oxygen but only if the metal is a heavy metal (has a mass greater than silver)
