# How do you find the heat capacity ratio of combustion products?

For example, if gaseous oxygen $$(O_2)$$ and paraffin wax $$(C_{32}H_{66})$$ were to stoichiometrically combust at STP, how would one go about finding the heat capacity ratio ($$\gamma={c_p \over c_v}$$) of the resulting mixture of gases? I'm guessing that it involves finding the adiabatic flame temperature? (but idk how lol)

• What is the approximate temperature and pressure that you want this ratio? Do you know the mole fractions of the constituents in the product mixture? – Chet Miller Aug 8 '19 at 11:28
• Maybe around 3160K and 290kPa. As for the mole fraction, the product mixture is comprised of ~20% CO, ~20%$CO_2$, ~30%$H_2O$, ~10%$O_2$, ~10%OH, and trace amounts of other stuff. – David Lu Aug 8 '19 at 21:30
• At that temperature and relatively low pressure, the gas mixture will exhibit close to ideal gas behavior. For an ideal gas mixture, each heat capacity is equal to the pure species heat capacities weighted in proportion to their mole fractions. – Chet Miller Aug 8 '19 at 22:52