Combustion is defined as the burning of hydrocarbon fuels in the presence of excess oxygen to produce carbon dioxide, water vapor, and heat. Oxygen will react with copper to produce copper oxide (either CuO or Cu2O depending on the oxidation state of the copper). This is a slow reaction that produces no carbon dioxide or water or heat. This is because copper is a metal and not a hydrocarbon. A hydrocarbon is a chemical that contains only carbon and hydrogen. Butane (C4H10) is a perfect example of a hydrocarbon. Because it contains carbon and hydrogen, it will combust according to the following reaction:
C4H10 + 6.5O2 --> 4CO2 + 5H2O
So butane is clearly the combustion reaction.
When oxygen reacts with metallic copper it forms metal oxide i.e cupurous oxide(Cu2O) or cupric oxide (CuO)
The reaction is :-
Cu(s) + O2(g) --------> CuO(s)
4Cu(s) + O2(g) ------> 2Cu2O(s)
This reation is thus the oxidation reaction.
Now, when oxygen reacts with carbon compounds,the combustion reaction occurs in which the oxides of the individual elements of the compound will be formed.Thus, the reaction of oxygen with butane will be:-
C4H10(g) + (13/2)O2(g) ---------> 4CO2(g) + 5H2O(l)
Here in this reactionoxides of carbon i.e carbon dioxide and hydrogen i.e water are formed.
This reaction is therefore the combustion reaction.
Oxygen will react with the metal copper. It will also react with the nonmetallic compound butane (C4H10). Which of these reactions is a combustion reaction?
In order to solve this question, you must understand the concept of combustion and corrosion. Both involve reactions with oxygen, but corrosion involves oxygen reacting with a metal such as copper and iron. On the other hand, a combustion reaction involves oxygen with a fuel; fuels in this sense, refers to organic compounds (mostly hydrocarbons), compounds that contain carbon atoms.
Thus in this question, compound butane reacting with oxygen is a combustion reaction. This is because compound butane (C4H10) is an organic compound. For more information about organic compounds, refer to the links below.
Also in answering the other two questions, you must remember that a combustion reaction is an exothermic reaction. This is because it emits heat during the reaction. This is an easy concept if you think of the butane gas burning in reaction. When the butane gas burns, the surroundings get warm and this is an indication that the reaction is an exothermic reaction.
For question C, the oxidizing agent is a compound that reduces the other compound in reaction. In the combustion reaction, however, oxidation does not occur since the oxidation number for carbon in the reactants and the products is the same. (C4H10 + excess O2->4CO2 + 5H2O)