Conceptual Questions
3.1 Thermodynamic Systems
Consider these scenarios and state whether work is done by the system on the environment (SE) or by the environment on the system (ES): (a) opening a carbonated beverage; (b) filling a flat tire; (c) a sealed empty gas can expands on a hot day, bowing out the walls.
3.2 Work, Heat, and Internal Energy
Is it possible to determine whether a change in internal energy is caused by heat transferred, by work performed, or by a combination of the two?
Why does a bicycle pump feel warm as you inflate your tire?
Is it possible for the temperature of a system to remain constant when heat flows into or out of it? If so, give examples.
3.3 First Law of Thermodynamics
What does the first law of thermodynamics tell us about the energy of the universe?
A great deal of effort, time, and money has been spent in the quest for a so-called perpetual-motion machine, which is defined as a hypothetical machine that operates or produces useful work indefinitely and/or a hypothetical machine that produces more work or energy than it consumes. Explain, in terms of the first law of thermodynamics, why or why not such a machine is likely to be constructed.
3.4 Thermodynamic Processes
When a gas expands isothermally, it does work. What is the source of energy needed to do this work?
If the pressure and volume of a system are given, is the temperature always uniquely determined?
It is unlikely that a process can be isothermal unless it is a very slow process. Explain why. Is the same true for isobaric and isochoric processes? Explain your answer.
3.5 Heat Capacities of an Ideal Gas
How can an object transfer heat if the object does not possess a discrete quantity of heat?
Most materials expand when heated. One notable exception is water between and which actually decreases in volume with the increase in temperature. Which is greater for water in this temperature region, or ?
Why are there two specific heats for gases and , yet only one given for solid?
3.6 Adiabatic Processes for an Ideal Gas
Would you expect to be larger for a gas or a solid? Explain.
There is no change in the internal energy of an ideal gas undergoing an isothermal process since the internal energy depends only on the temperature. Is it therefore correct to say that an isothermal process is the same as an adiabatic process for an ideal gas? Explain your answer.
Does a gas do any work when it expands adiabatically? If so, what is the source of the energy needed to do this work?