When you burn a hydrocarbon what is given off?

Answer 1

Hydrocarbons contain (ideally) hydrogen and carbon. When they are burned the hydrogen reacts with oxygen from the atmosphere to produce water H2O (usually steam) and the carbon reacts with more oxygen to produce carbon dioxide CO2.

Both these processes release a lot of heat (they are exothermic) and the heat is often used to drive a heat engine, which could be a petrol or diesel engine or a gas turbine. The heat can also be used to turn water into steam which is used in a steam turbine, another type of heat engine.

Hydrogen, carbon and oxygen have atomic weights of 1, 12 and 16. A hydrocarbon fuel like gasoline has approximately two hydrogen atoms for each carbon atom. 1 kg of fuel contains about 80% carbon and the molecular weight is about 14. Burning brings in two atoms of oxygen for each carbon atom, and one more atom of oxygen for the two hydrogen atoms. That means that 14 kg of fuel uses approximately 48 kg of oxygen to produce 44 kg of CO2 plus 18 kg of water.

The above is an approximate estimate of the principles involved, but is useful as a guide for the hydrocarbon fuels used in vehicles. One kg of fuel gives rise to approximately 3 kg of carbon dioxide.

A light gas like methane CH4 has proportionally more hydrogen, so 1 kg of fuel contains exactly 75% carbon, so the amount of carbon dioxide produced by burning is slightly less. Gas is seen as a 'clean' fuel but it is only slightly cleaner than oil fuels, because 100 lb of methane still contains 75 lb of carbon.

Answer 2

Carbon dioxide and water are the main products if burnt in an excess of oxygen. If the oxygen is limited, some of the carbon can form carbon monoxide as an alternative.

Hydrocarbons can have a variety of other elements so it is possible to see smaller amounts of other gases being produced.

Answer 3

It depends on if there is complete or incomplete combustion.
In complete combustion, the products are carbon dioxide (CO2) and water (H2O).
In incomplete combustion, the products are carbon monoxide (CO), carbon (C) and water (H2O).

Answer 4

CO2 and H2O and traces of carbon monoxide and unburned hydrocarbons.

Answer 5

Whenever a hydrocarbon is burnt, the products are Carbon dioxide and Water.Therefore

the gas is CO2 .

Answer 6

Carbon dioxide and water vapors are released.

Answer 7

The products are water and carbon dioxide.

Answer 8

Water vapor and carbon dioxide.