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## Homework Statement

Premium gasoline produces

__1.23×10__of heat per gallon when it is burned at a temperature of approximately 400ºC (although the amount can vary with the fuel mixture). If the car's engine is

^{8}J__25.0% efficient__,

__three-fourths of that heat is expelled into the air__, typically at

__20.0ºC.__

a) If your car gets

__35.0 miles per gallon__of gas, by how much does the car's engine change the entropy of the world when you drive

__1.00 mile__?

b) Does it decrease or increase the entropy of the world?

## Homework Equations

ΔS = ΔS

_{HOT}+ ΔS

_{COLD}

## The Attempt at a Solution

a) ΔS = ΔS

_{HOT}+ ΔS

_{COLD}

ΔS = -((.75*(1.23*10

^{8}J/gal)*(1 gal/35 mile)*(1 mile))/(400+273 K) + ((.75*(1.23*10

^{8}J/gal)*(1 gal/35 mile)*(1 mile))/(20+273 K)

ΔS = -3916 J/K + 8996 J/K

ΔS = 5079 J/K

b) Entropy increases (positive value for part a)

Would both ΔS

_{HOT}and ΔS

_{COLD}be multiplied by .75, or would one be multiplied by the .25 efficiency?