80 likes | 288 Views
Classification of Chemical Reactions. Notes. Composition (also called combination or synthesis). Two reactants combine to form one product A + B AB Example: 3Na + P Na 3 P Helpful hints
E N D
Composition (also called combination or synthesis) • Two reactants combine to form one product • A + B AB • Example: 3Na + P Na3P • Helpful hints • An element plus another element will always be composition; if there is only one product, it has to be composition • Note that composition reactions are redox reactions
Decomposition • One reactant breaks down (decomposes) into two (or more) products • AB A + B • Example: 2HgO 2Hg + O2 • Helpful hints • If there is only one reactant, it has to be decomposition • Note that decomposition reactions are redox
Single Replacement (Redox) • An element takes the place of a similar element (in terms of charge) in a compound • A + BC AC + B or • D + BC BD + C • Examples: 3Na + AlCl3 3NaCl + Al F2 + 2NaCl 2NaF + Cl2 • Helpful hints • An element plus an ionic compound will usually be single replacement; there are always 2 reactants and 2 products
Single Replacement continued • Hydrogen is often a participant in redox single replacement reactions • The activity series or a table of standard reduction potentials must be used to determine if a s.r. redox reaction will occur
Double Replacement (Ionic) • The + and – ions in two ionic compounds switch partners • AB + CD AD + CB • Example: 2Na3PO4 + 3CaCl2 Ca3(PO4)2 + 6NaCl • Helpful hints • Two ionic compounds yield two ionic compounds; remember a + ion always goes with a – ion and the + is written first in the formulas
Combustion • A hydrocarbon (a compound made up of carbon, hydrogen, and sometimes oxygen) reacts with oxygen, or burns, to give carbon dioxide plus water • CxHy + O2 CO2 + H2O or CxHyOz + O2 CO2 + H2O • Example: CH4 + 2O2 CO2 + 2H2O • Helpful hints • Oxygen is always a reactant and the products are always carbon dioxide and water! • These are also redox reactions