Writing Equations Cheat Sheet
Combustion:
1. Hydrocarbon (or alcohol) + oxygen = carbon dioxide + water (if complete)
2. Hydrocarbon (or alcohol) + oxygen = carbon monoxide + water (if incomplete)
3. Ammonia + oxygen (limited) = NO + water
4. Ammonia + oxygen (excess) = nitrogen dioxide + water
5. Sulfides + oxygen = oxide + sulfur dioxide
6. Hydride + oxygen = water + oxide
Synthesis:
1. element + element = compound
2. metal oxide + water = base (OH)
3. nonmetal oxide + water = acid (H)
4. metal oxide + nonmetal oxide = salt (ionic compound)
Decomposition reactions
1. binary compound = element + element
2. metal carbonate = metal oxide + carbon dioxide
3. metal chlorate = metal chloride + oxygen
4. ammonium carbonate = ammonia + water + carbon dioxide
5. sulfurous acid = sulfur dioxide + water
6. carbonic acid – water + carbon dioxide
7. hydrogen peroxide = water + oxygen
8. ammonium hydroxide = ammonia + water
9. ammonium nitrate (heat) = nitrogen + water + oxygen
10. metal sulfite = metal oxide + sulfur dioxide
Single Replacement:
A + BX = B + AX
X + AY = Y + AX
Double Replacement:
1. AX + BY = AY + BX
2. Sulfide salt + acid = salt + hydrogen sulfide (gas)
3. Carbonate salt + acid = carbon dioxide (gas) + water + salt
4. Sulfite salt + acid = sulfur dioxide(gas) + water + salt
5. Ammonium salt + hydroxide(strong) in the presence of heat = ammonia(gas) + salt + water
Acid/Base Reactions:
Acid + Base = Water + Salt
Acid anhydride + strong base = water + salt
**Note the concentration of the acid and base: - sulfuric and phosphoric acids are exceptions from the rules.
If base is in excess, will react completely to form salt and water.
If equal amounts of acid and base react, form water and sodium hydrogen sulfate/phosphate – will only take one of
their hydrogen to make water the other is left with the salt
Sulfuric acid, carbonic acid, and ammonium hydroxide are unstable in solution. They will break down as follows:
H2SO4 → H+ + HSO4H2CO3 → H2O + CO2
NH4OH → NH3 + H2O
Coordination Compounds:
Key word is the ligand is usually in excess.
Transition metal + ligand (NH3, CN-, SCN-, OH-) = complex ion
**The number of liqands will often be twice the charge of the metal ion.
Ag+ + NH3  Ag(NH3)2+
Complex ion + acid = metal ion + ligand with and extra H +
Cu(NH3)4+2 + H+  Cu+2 + NH4+
Strong Acids: HCl, HNO3, H2SO4, HClO4, HClO3, HBr, HI
Strong Bases: Group I hydroxides and Ca(OH)2, Sr(OH)2 and Ba(OH)2
Common Oxidizing Agents:
MnO4- in acidic solution
MnO2 in acidic solution
MnO4- in a neutral or basic solution
Cr2O7-2 in acidic solution
HNO3 concentrated
HNO3 dilute
H2SO4 hot, concentrated
Metallic ions (higher oxidation #)
Free halogens
Na2O2
HClO4
C2O4-2
H 2O 2
IO3- and BrO3-
Product formed:
Mn+2
Mn+2
MnO2(s)
Cr+3
NO2
NO
SO2
metallous ion (lower oxidation #)
halide ions
NaOH
ClCO2
O2 and water
free halogen
Common Reducing Agents:
Halide ions
Free metals
Sulfite ions or SO2
Nitrite ions
Free halogens, dilute basic solution
Free halogens, concentrated basic solution
Metallous ions (lower oxidation #)
Products formed:
free halogen
metal ions
sulfate ions
nitrate ions
hypohalite ions
halate ions
metallic ions (higher oxidation #)