Combustion Mr. Fleming

Content Standard D 14.  Describe combustion reactions of hydrocarbons and their resulting by-products.

Big Questions What is the difference between complete and incomplete combustion? What do you need for the a combustion reaction to happen? What is produced by a combustion reaction?

Whoosh Bottle https://www.youtube.com/watch?v=AS8TDpF P0OQ

Combustion Rapid chemical combination of a substance with oxygen, producing heat and light. Burning Exothermic chemical reaction. Creates heat (light glowing/flame) Fuels = organic compounds (especially hydrocarbons) in the gas, liquid or solid phase.

Combustion

Combustion

A molecule of Paraffin (Wax) has the following structure A molecule of Paraffin (Wax) has the following structure. The combustion reaction for Paraffin is: 2 C20H42 + 61 O2 g 40 CO2 + 42 H2O This assumes that there is enough oxygen to completely react with the paraffin. The reaction that takes place follows the sequence of events shown on the following slides.

An oxygen molecule collides with the Paraffin molecule and reacts with that portion of the molecule.

This breaks the molecule into smaller segments and draws off a Carbon atom and two Hydrogen atoms to form Carbon monoxide and Water.

Another oxygen molecule collides with the Paraffin molecule and reacts with that portion of the molecule.

This breaks the molecule into even smaller segments and draws off another Carbon atom and two more Hydrogen atoms to form Carbon monoxide and Water. An oxygen molecule collides with the 2 Carbon monoxide atoms that were formed in the previous 2 steps to form 2 Carbon dioxide molecules.

Combustion Recall What are the reactants in a combustion reaction? Oxygen & Hydrocarbon What are the products in a combustion reaction? Energy, Water, C02

Incomplete vs Complete Combustion

Incomplete vs Complete Combustion Complete combustion is when all reactants are turned into products. There are no “leftovers” Ex- cellular respiration Incomplete combustion is when some (or most) of the reactants are turned into product. There is “leftovers” Carbon Monoxide Soot Ex- candles burning, car engines http://www.chemistryhelp.net/basic-chemistry/complete-and-incomplete-combustion

Combustion Recall What is the difference between complete and incomplete combustion? Complete combustion is when all reactants are turned into products, and incomplete combustion not all reactants are turned into products.