Combustion of hydrocarbons (compounds that contain only hydrogen and carbon) produces carbon dioxide and water. "Combustion" implies that a fuel is reacting with oxygen.

C_mH_n + O₂(g) → Co₂(g) + H₂O(L)

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Precipitation reactions can be recognized by the presence of a solid, insoluable ionic compound products in the reaction where aqueous reactants are combined. 

AX(aq) + BY(aq) → AY(s) + BX(aq)

Mg(NO₃)₂(aq) + Na₂CO₃(aq) → MgCO₃(s) + 2NaNO₃(aq)

Gas forming reactions can be recognized by the presence of a gas-phase product (g) in a reaction in which the reactants are not gaseous (usually aqueous solutions). One reactant is acid or base.

CX(aq) + DY(aq) → CY(g) + DX(aq)

Neutralization reactions (or acid base) occure when an acid and a base are the reactants, and the products are H₂O and an ionic compound ("salt")

HX(aq) + BOH (aq) → BX(aq) + H₂O(L)

HI(aq) + KOH(aq) → KI(aq) + H₂O(L)

Reduction-oxidation reactions can be recognized by noticing whether the oxidation numbers of any of the elements involved in the reaction changed between the reactant and the product side.

2Fe(s) + 3O₂(g) → Fe₂O₃(s)

H₂SO₄(aq) + 8HI(aq) → H₂S(aq) + I₂(g) + 4H₂O(L)

Formation

Formation reactions involve the creation of a compound from its component elements in the standard states

element + element → compound

N₂(g) + 3H₂(g) → 2NH₃(L)

Decomposition reactions can be identified...

compound → element + element

2NH₃(g) → N₂(g) + 3H₂(g)