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### 8.13 - Understanding the Solution

Posted: Sat Jan 20, 2018 11:18 am
For question 8.13, "In a combustion cylinder, the total energy change produced from the burning of a fuel is -2573 kJ. The cooling system that surrounds the cylinder absorbs 947 kJ as heat. How much work can be done by the fuel in the cylinder?"

The answer, 1626 kJ...Is that the amount of expansion work done by the combustion? And do you subtract the 947 kJ because the cylinder is trying to cool the reaction?

### Re: 8.13 - Understanding the Solution

Posted: Sat Jan 20, 2018 11:32 am
947kJ should be positive because the system is absorbing the heat in order to cool down, which means it's an endothermic process. Work done by the system produces a negative work value.

### Re: 8.13 - Understanding the Solution

Posted: Sat Jan 20, 2018 11:38 am
The answer, 1626 kJ refers to how much work can be done by the fuel in the cylinder. You subtract 947 kJ because this amount of energy was lost to the surroundings as heat.