Final answer:
The standard heat of the reaction 2C2H6 + 7O2 = 4CO2 + 6H2O is calculated to be -2855.4 kJ using the standard heat of formation values for the reactants and products.
Step-by-step explanation:
To calculate the standard heat of the given exothermic reaction (2C2H6 + 7O2 = 4CO2 + 6H2O), we need to use the standard heat of formation data provided for the reactants and products. The heat of reaction, also known as enthalpy change (ΔH), can be calculated using the formula: ΔH = ∑ΔHf(products) - ∑ΔHf(reactants).
Now, performing the calculations:
ΔH = [(4 x -393.5) + (6 x -241.8)] - [(2 x -84.7)]
= (-1574 + -1450.8) - (-169.4)
= -3024.8 + 169.4
= -2855.4 kJ per 2 moles of C2H6 burned.