Stearic acid (C18H3602) is a fatty acid, a molecule with a long hydrocarbon chai

Question

Stearic acid (C18H3602) is a fatty acid, a molecule with a long hydrocarbon chain and an organic acid group (COOH) at the end. It is used to make cosmetics, ointments, soaps, and candles and is found in animal tissue as part of many saturated fats. In fact, when you eat meat, you are ingesting some fats containing stearic acid, Determine the Hmn for this combustion given the following information: Hf of stearic acid =-948 kJ/mol, Hf of CO2 =-394 kJ/mol, , of water--242 mol. Calculate the heat (a) released in kJ when 297.9 g of stearic acid reacts with 943.2 g of oxygen. Enter a positive number to O decimal place

Explanation / Answer

C18H36O2(s) + 26O2(g) ---> 18CO2(g) + 18H2O(G)

DHrxn = (18*CO2+18*H2O)-(1*C18H36O2+26*O2)

      = (18*-394+18*-242)-(1*-948+26*0)

      = -10500 Kj

nO of mol of stearic acid = 297.9/284.5 = 1.05 mol

no of mol of O2 = 943.2/18 = 52.4 mol

limiting reactant = stearic acid

heat released(q) = 1.05*10500

                = 11025 kj

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