MediumChemistryHigh School (11–12)Chemical Thermodynamics › Systems, Work, Heat and the First LawNumericalpython
A gas goes through a cycle of three steps and ends in its starting state.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A gas goes through a cycle of three steps and ends in its starting state. In step 1 it absorbs J of heat and does J of work. In step 2 it gives out J of heat, with no work. In step 3 it gives out J of heat. Find for the whole cycle, the net heat, and the work in step 3.
Need a reminder? The key ideaShow
First law: . Energy into the system is positive: for heat absorbed, for work done on the system. Adiabatic change: , so . For a whole cycle, .
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The cycle. The gas returns to its starting state, so .
Step 2. Net heat. J.
Step 3. Net work. , so J.
Step 4. Step 3. , so J. Work is done on the gas in step 3.
Answer: , net heat J, and J.
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