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# Work Efficiency for a System

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You have a system with a movable piston that is isolated. The reaction inside the system is under adiabatic conditions. When the reaction (the burning of butane in oxygen) is started, the distance the piston traverses is 30.00 cm at 1.000 atm of pressure, the diameter of the piston is 8.000 cm. If you take 15.00 mg of butane and a stoichiometric amount of oxygen, what is the work efficiency of this system; that is the percent of the energy produced that is used for work? The heats of formation of the C4H10, CO2(g), and H2O(g) are ?126.00 kJ/mol, ?393.50 kJ/mol, and ?241.80 kJ/mole, respectively. The conversion factor to change atm L to joules is 101.3250274 J/atm L.

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#### Solution Preview

So first we find work done by using the formula W = -PdV = -Px 4x 3.14 x r^2 h = -1507.96 atm cm^3 (r = 8/2, h = 30)
Convert cm^3 to L by dividing by 1000. We get W = -1.5 L ...

#### Solution Summary

The expert examines work efficiency for a system.

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