Using enthalpies of formation, calculate the quantity of heat produced when 14.0 g of propane is completely combusted in air under standard conditions. Assume that liquid water is forming

The balanced chemical reaction here is:

C3H8 (g) + 5O2 (g) - - > 3CO2 (g) + 4H2O (l)

Calculating for the molar change in enthalpy:

Enthalpy change = 3 (-393.5) + 4 (-285.83) - (-103.85) = - 2220.0 kJ/mole

Now, propane has a molar mass of 44g/mol. So, for us to calculate the heat released by burning 14 grams of propane, we have:

-2220 kJ/mole * (14g / 44g/mol) = - 706.36 kJ

Answer:

-706.36 kJ

(negative means heat is released)