thebest Posted November 19, 2011 Report Share Posted November 19, 2011 Whats the diff between a combustion reaction and just heating a substance? Also, in a combustion reaction, are the products always carbon dioxide and water, or is it a common oxide of the reactant and water? Reply Link to post Share on other sites More sharing options...
CkyBlue Posted November 19, 2011 Report Share Posted November 19, 2011 Heating a substance isn't really a reaction. I'm pretty sure heating it won't change any of the chemical properties. Combustion reactions include adding oxygen to the other reactant, which is not the same thing as heating it. In a combustion reaction, I think I've only most often seen the combustion of hydrocarbons, and their product is always CO2 and H2O, so that's where I think you might be getting that notion from. In combustion, the end product (pardon my language) is different from the reactants, whereas you basically have the same thing when you heat something, although it may have changed its state.I think combustion usually occurs for hydrocarbons, but it could also occur for hydrogen gas, (H2) to make water. I'm not sure about other examples though. 1 Reply Link to post Share on other sites More sharing options...
Emmi Posted November 19, 2011 Report Share Posted November 19, 2011 In addition, a combustion reaction can be either complete or incomplete. I'll use hydrocarbons here, because it's a good example. If the reaction is complete, then the products are CO2 and H2O. If the reaction is incomplete, then there's not enough oxygen available to react fully with the hydrocarbon, and you'll have some CO and soot formed in addition to the CO2 and H2O. 1 Reply Link to post Share on other sites More sharing options...
thebest Posted November 20, 2011 Author Report Share Posted November 20, 2011 Thanks alot guys. i have another question. If there is a combustion reaction with reactants CxHyOz (x y z are unknown subscript numbers) + O2, and a question asks calculate the MASS OF OXYGEN CONSUMED using conservation of mass principle (i have the masses of all the other things), do i find the mass of just oxygen gas, O2, or the mass of oxygen in the ENTIRE reactants which is including the oxygen in CxHyOz? Srry, just kinda confused on the wording. :/ Reply Link to post Share on other sites More sharing options...
dessskris Posted November 20, 2011 Report Share Posted November 20, 2011 find the equation of the reaction first? then you can perhaps use ratio to find out the mass of oxygen reacted :/ I don't really get you though, what do you have and what do you know? Reply Link to post Share on other sites More sharing options...
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