Liquid octane $(C_8{H}_{18})$ at $77F,1$ atm enters a combustion chamber operating at steady state and burns completely with $50\%$ excess dry air entering at $120F,1$atm. The products exit at $1200F,1$atm. Determine the magnitude of the rate of heat transfer between the combustion chamber and its surroundings, in Btu per Ibmol of fuel entering. Kinetic and potential energy effects are negligible.

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Btu$/$lbmol $(C_8{H}_{18})$