4.2 Types of Chemical Reactions
| TYPES OF CHEMICAL REACTIONS | |
|---|---|
| Combination | Two (or more) substances combine to form a new substance. 4Na(s) + O2(g) → 2Na2O(s) |
| Decomposition | One substance is converted into 2 or more substances. CaCO3(s) → CaO(s) + CO2(g) |
| Combustion | Combustion of a hydrocarbon specifically always involves a reaction with O2 to produce CO2 and H2O. Combustion reactions are a type of redox reaction. CH4(g) + O2(g) → CO2(g) + H2O(g) |
| Oxidation-Reduction (a.k.a. Redox) | A reaction in which electrons are transferred from one species (oxidized) to another species (reduced). The evidence that a redox reaction has occurred is changes in oxidation states (charges). 2H2O(l) → 2H2(g) + O2(g) |
| Single Replacement | An element reacts with an ionic compound or acid to replace an element in the compound. Zn(s) + Cu(NO3)2(aq) → Cu(s) + Zn(NO3)2(aq) |
| Double Replacement | Two aqueous ionic compounds (and/or acids) are mixed with cations and anions trading partners to form two new ionic compounds (and/or acids). Hg(NO3)2 (aq) + (NH4)2S(aq) → HgS(s) + 2NH4NO3(aq) |