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A gas in a cylinder absorbs 520 J of heat from a flame.

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A gas in a cylinder absorbs $520$ J of heat from a flame. At the same time it pushes out a piston, doing $210$ J of work on the surroundings. Write down $q$ and $w$ with their signs, and find $\Delta U$ .

Need a reminder? The key ideaShow

First law: $\Delta U = q + w$ . Energy into the system is positive: $q > 0$ for heat absorbed, $w > 0$ for work done on the system. Adiabatic change: $q = 0$ , so $\Delta U = w$ . For a whole cycle, $\Delta U = 0$ .

The worked solution

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← Two identical flasks each hold 0.250 mol of nitrogen at 298 K and 1.00 bar, in a volume of 6.20 L.A gas in an insulated cylinder is compressed by 450 J of work. →

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A gas in a cylinder absorbs 520 J of heat from a flame.

The worked solution

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