Acetylene torches utilize the following reaction: 2 C2H2 (g) + 5 O2 (g) -----> 4 CO2 (g) + 2 H20 (g) How to calculate Delta H in Celsius for this reaction ? Species Delta H C2H2 (g )= +226.7 CO2 (g )= -393.5 H20 (g) = -241.6
To calculate the enthalpy of combustion of acetylene,
More specifically, you need to subtract from the sum of enthalpies of formation of the products the sum of the enthalpies of formation of the reactants.
Keep in mind that each of these enthalpies must be multiplied or divided in accordance to their stoichiometric coefficients from the balanced chemical reaction.
So, the balanced chemical reaction is
You were given the enthalpies of formation for 1 mole of
But notice that the balanced chemical reaction has 2 moles of
Now the expression for the enthalpy of combustion will be
Therefore, the enthalpy of combustion for acetylene is
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