Combustion reactions

Recall Most chemical reactions fall into the five families of reactions that we will be studying in our course: Synthesis Decomposition Single Displacement Double Displacement Combustion Today we will focus the last family of reactions: combustion.

Learning Goals We are learning to identify hydrocarbons. We are learning to balance combustion reactions.

Hydrocarbons Organic compounds contain carbon as its building block. Hydrocarbons are organic compounds of hydrogen and carbon in various combinations.

Fossil fuels hydrocarbons formed underground over millions of years from the remains of once-living organisms. 95% of all hydrocarbons are burned as fuels because the combustion reaction is exothermic (releases heat).

Naming of Hydrocarbons Carbon is an element that can bond with up to 4 others. As a result, hydrocarbons form a predictable chain-like structure. Some examples Methane (CH4) Ethane (C2H6) Propane (C3H8) What is the general formula for determining the number of hydrogens if you know the number of carbons???

Hydrocarbon Naming Chart Use the prefix chart below and add –ane as the suffix. What is the chemical formula for hexane??? Number Prefix 1 meth- 6 hex- 2 eth- 7 hept- 3 prop- 8 oct- 4 but- 9 non- 5 pent- 10 dec-

Combustion reaction a chemical reaction in which a compound or element rapidly combines with oxygen gas these reactions usually give off a large amount of heat and light

Combustion Reaction CnH2n+2 + Oxygen Carbon Dioxide + Water Have the skeleton form: This reaction is when we have complete combustion only. CnH2n+2 + Oxygen Carbon Dioxide + Water

Problems with Incomplete Combustion In order for a combustion reaction to be complete, proper access to oxygen is important. Should there be an insufficient supply of oxygen, the toxic gas carbon monoxide (CO) can be produced. This is called incomplete combustion. In your homes, insufficient oxygen supplies for any combustion (i.e furnace) can be caused by blocked intakes / vents from the outdoors amongst other things. This is why all homes must have a CO detector.

Example #1 Given the word equation of the single displacement reaction below, determine the balanced chemical equation. Butane + Oxygen Gas  Carbon Dioxide + Water

Solution 2 13 4 C4H10 + 13/2 5 O2 8 CO2 + 10 H2O # R Atom # P 4 8 C 1 20 H 2 10 20 2 13 26 3 9 O 13 21 26 But wait … there is another way! Complicated, yet easier!!!

Learning Goals We are learning to identify hydrocarbons. We are learning to balance combustion reactions.

Homework P.251 #2,3 P.258 #7, 9 (quiz review)