Which gives off more heat when burning CH4 or CH3OH and why?
I think it would be CH3OH, but I am not sure and cannot find any information on the reason why. Does any one have any suggestion? Am I even right to begin with? Thanks.
I would say CH3OH too because it has oxygen and oxygen produces heat i think but I'm no chemist
brad
Do you know how to calculate the heat of the reaction; i.e., delta Hrxn?
Write the equations.
CH4 + 2O2 ==> CO2 + 2H2O
CH3OH + 2O2 ==> CO2 + 2H2O
Now look up in your text the delta Hof for each of the products and reactants (elements are zero)
delta Hrxn = delta Hproducts - delta Hreactants
Let me know if you need additional assistance but explain what you don't understand.
To determine which substance gives off more heat when burning, we can compare their enthalpies of combustion. The enthalpy of combustion is the amount of heat released when 1 mole of a substance is burned completely in oxygen.
First, let's compare the chemical reactions for burning methane (CH4) and methanol (CH3OH):
1) CH4 + 2O2 -> CO2 + 2H2O
2) CH3OH + 1.5O2 -> CO2 + 2H2O
From these reactions, we can see that both methane and methanol produce carbon dioxide (CO2) and water (H2O) when burned. However, the stoichiometric coefficients and the number of oxygen molecules required differ for each substance.
When we calculate the enthalpies of combustion for each substance, we find that the enthalpy change (ΔH) is more negative for methanol than methane. This means that more heat is released during the combustion of methanol compared to methane.
The enthalpy change of combustion for methane (CH4) is approximately -890 kJ/mol, while for methanol (CH3OH), it is approximately -726 kJ/mol. Therefore, methanol releases more heat when burned compared to methane.
The reason behind methanol's higher enthalpy of combustion can be explained by its molecular structure. Methanol contains oxygen atoms, which can contribute to the combustion process and result in more energy being released.
Please note that these values are approximate and can vary depending on specific conditions and reference sources.