COMPLETE AND INCOMPLETE COMBUSTION

COMPLETE COMBUSTION In a combustion reaction, oxygen combines with another substance and releases energy in the form of heat and light. When oxygen is available in sufficient amounts complete combustion occurs

VIDEOS Video http://www.youtube.com/watch?v=q3tf9OxBdYc http://www.youtube.com/watch?v=UygUcMkRy_c http://www.youtube.com/watch?v=jw3ZRmKUKyA

COMPLETE COMBUSTION This means that all of the carbon atoms and hydrogen atoms from the hydrocarbon molecules combine with oxygen atoms to form carbon dioxide and water. WHAT IS A HYDROCARBON?? A hydrocarbon is a compound that is composed only of the elements carbon and hydrogen.

CxHy + (4x+y)/4 O2 –> x CO2 + y/2 H2O COMPLETE COMBUSTION the general equation of the complete combustion of a hydrocarbon is: CxHy + O2 –> CO2 + H2O CxHy + (4x+y)/4 O2 –> x CO2 + y/2 H2O

COMPLETE COMBUSTION Complete combustion is a more efficient process for generating heat since the flame is mostly heat and little light.

INCOMPLETE COMBUSTION When a reaction has too little oxygen incomplete combustion is the result. A bright yellow flame is produced during incomplete combustion. In addition to this, soot and toxic carbon monoxide can also be formed through incomplete combustion

INCOMPLETE COMBUSTION An example equation of the incomplete combustion of propane is: 2C3H 8 (g) + 7O2 (g)  2C(s) + 2CO(g) + 2CO2(g) + 8H2O (g)

INCOMPLETE COMBUSTION The products of incomplete combustion include carbon dioxide and water vapour as well as carbon, carbon monoxide or both Incomplete combustion is a more inefficient process for generating heat since it has less oxygen and therefore more light is produced rather than heat. This will be seen with a more yellow flame.

Carbon Monoxide Why is the formation of carbon monoxide a serious concern? Carbon monoxide is a toxic gas that is both colourless and odourless. Carbon monoxide can bind to oxygen in the blood which will decrease the number of available oxygen binding sites in a person. Symptoms of carbon monoxide poisoning include headache, dizziness, and nausea. Eventually suffocation can be a result of carbon monoxide poisoning. Proper ventilation and the use of carbon monoxide detectors in the home can help to prevent carbon monoxide poisoning. - If you were in a location where carbon monoxide is being produced. Where is the safest place to be in relation to carbon monoxide ie how does it distribute itself through an area?

Complete and Incomplete Combustion using Propane Propane + oxygen  carbon dioxide + water C3H8 (g) + 5 O2  3 CO2 + 4 H2O Propane + oxygen  carbon + carbon dioxide + water C3H8 (g) + 3 ½ O2  1 ½ C + 1 ½ CO2 + 4 H2O Oxygen is limited and therefore carbon is produced as a result.

COMPLETE AND INCOMPLETE COMBUSTION Since incomplete combustion occurs when there is not enough oxygen. Design an experiment where you can test this hypothesis. We will be looking into this further in next Wednesdays lab. A little bit of gas with no oxygen is fine but once it has the oxygen to combine with then you will form into complete combustion a lot of oxygen it will be incomplete.

Practice Problems What is a hydrocarbon? Why is incomplete combustion potentially hazardous? What types of energy do combustion reactions release? Write a balanced chemical equation for the complete combustion of heptane, C7H16.

Practice Problems Complete the handout.