Types of Chemical Reactions 5 Categories Formation Decomposition Combustion Single Replacement Double Replacement

Formation Reactions (synthesis) 2 elements combine to form a compound X + Y = XY i.e. Na(s) + Cl2(g)  NaCl(s) Pg. 104, Fig. 3.15 Fig. 3.16

Decomposition Reactions one compound breaks down into two or more simpler compounds or elements (opposite of formation reactions) XY  X + Y 2 H2O(l)  2H2(g) + O2(g) (electrolysis of H2O)

Decomposition of Ammonium Nitrate NH4NO3(s)  N2O(g) + 2H2O(g)

Hydrocarbon Combustion A hydrocarbon (CnHn) (i.e. oil, fuel, natural gas) reacts with oxygen gas to form carbon dioxide gas and water vapor and heat. i.e. CH4(g) + O2(g)  CO2(g) + H2O(g) + thermal energy

Complete Combustion Complete combustion: plenty of O2(g) – all hydrocarbons burned to CO2(g) and H2O(g)

Incomplete Combustion: not enough O2(g) for complete combustion • products are CO2(g) + H2O(g) + carbon soot + CO(g) • carbon monoxide – colorless, odorless, highly toxic gas • CO(g)bonds 200x more strongly than O2(g) to hemoglobin, can be fatal (suffocation) • So NEVER operate fuel-burning apparatus without proper ventilation

Assignment Find the formation, decomposition and combustion reactions on the front page of your notes (there are 6) Complete all the practice problems on this handout.