Synthesis, Decomposition and Combustion Reactions

Synthesis In a simple synthesis reaction, two elements come together to form a compound Format: element + element  compound Must be able to predict Ex. Words: magnesium + oxygen  magnesium oxide Formula: Mg + O2  MgO Practice: Al + Cl2  _______ (Answer is not AlCl2, look at ions) There are also 2 other formats that you must be able to identify as synthesis, but do not have to predict Format 1: element + smaller compound  larger compound Ex. CO + O2  CO2 Format 2: smaller compound + smaller compound  larger compound Ex. Na2O +CO2 ---> Na2CO3

Decomposition In a simple decomposition reaction, one compound decomposes into two pure elements Format: compound  element + element Ex. MgO  Mg + O2 Practice: H2O  _____ (answer is not H2 + O) There are 2 other formats that you must be able to identify as synthesis, but do not have to predict Format 1: larger compound  element + smaller compound Ex. H2O2  H2O + H2 Format 2: larger compound  smaller compound + smaller compound Ex. NH4NO3  N2O + H2O

Combustion In a combustion reaction, a hydrocarbon reacts with oxygen to make CO2 and H2O Format: hydrocarbon + O2  CO2 + H2O Hydrocarbons contain C, H and O Examples of hydrocarbons: CH4 (methane), C3H8O(isopropyl alcohol) Combustion Examples: CH4 + O2  CO2 + H2O C3H8O + O2  CO2 + H2O Practice: C8H18 + O2 