Chapter 3 - Thermodynamics

What are the three types of heat transfer?

1. Conduction 2. Convection 3. Radiation

What are the 4 types of thermodynamic processes?

1. Isothermal 2. Adiabatic 3. Isobaric 4. Isovolumetric

What are the 9 state functions?

1. Pressure (P) 2. Density 3. Temperature 4. Volume 5. Enthalpy 6. Entropy 7. Potential Energy 8. Gibbs Free Energy 9. Internal Energy

What is body temperature in celsius and farenheit?

37, 98.6

What is an isolated system? Can internal energy change?

A system that is incapable of exchanging energy or matter with its surroundings. It follows that the total change in internal energy in an isolated system will be equal to 0.

What is a state function?

A thermodynamic property that is a function of only the current equilibrium state, not the path that was taken there.

What is a process function?

A thermodynamic property that is a function of the path taken to a certain state.

At what point will heat affect the temperature of an object that is undergoing a phase change?

After the phase change is complete. Changing phases requires its own heat energy and this cost must be paid first. Therefore, heat added to a 0 degrees celsius icecube will only cause the icecube to melt into water, not change the temperature. Once the ice cube is completely water, any additional added heat will raise the temperature.

What is the second law of thermodynamics?

Any given process must result in an increase in total entropy in the universe. In other words, things cannot go from disordered to more ordered spontaneously. For a specific example, consider heat. Heat will not flow from a cold object to a hot object, decreasing entropy. Instead, heat will always go from a hot object to a cold object in thermal contact until the temperatures of the objects are equal and the entropy of the universe is higher.

What is the formula for volumetric expansion?

Beta is volumetric expansion coefficient

What is it called when a gas goes to a liquid?

Condensation

What is it called when a gas goes to a solid?

Deposition

What is it called when a liquid goes to a gas?

Evaporation or Vaporization

What is it called when a liquid goes to solid?

Freezing or Solidification

In what direction(temperature wise) does heat flow?

From objects with high temperatures to objects with lower temperatures

What is it called when a solid goes to a liquid?

Fusion or Melting

What is the equation for linear thermal expansion?

Mnemonic: When temperature changes, the length changes ALOT

When do we assign positive or negative values to work?

Neg. when work is being done on the system (compression) Pos. when work is being done by the system (expansion). Applies to Q-W version --> so if system compresses it becomes Q+W because neg times neg equals pos

What does it mean to be in thermal equilibrium?

No net heat is flowing between objects in thermal contact.

Do two objects need to be in physical contact to be in thermal contact?

No, it is possible for objects to be in thermal contact without touching one another, although, objects in thermal contact are usually in physical contact too.

What is an open system?

One in which both matter and energy can be exchanged with the surroundings. (ex. boiling pot of water, humans)

What is a closed system?

One in which energy can be exchanged, but matter cannot. (ex. pistons)

What does it mean to be isochoric (isovolumetric) and how does that affect the first law of thermodynamics equation?

One in which no change in volume occurs. Without volume change (compression or expansion) there can be no work (W = 0). Change change in internal energy is equal to the heat added (ΔU = Q)

What does it mean to be adiabatic and how does that affect the first law of thermodynamics equation?

One in which there is no change in heat (Q = 0) ΔU = W (change in internal energy of the system = work done *on* the system)

What does it mean to be isobaric and how does that affect the first law of thermodynamics equation?

One in which there is no change in pressure (constant pressure). Keeping pressure constant does not affect U = Q - W

What is the specific heat of water?

Or 4.184 J/g ⋅ K

How does one calculate the change in entropy of a reversible process?

Q is heat gained or lost in a reversible process, T temp in kelvin

The flow of heat from an object with a high temperature to an object with a low temperature is?

Spontaneous

What is it called when a solid goes to a gas?

Sublimation

What is temperature proportional to and founded upon?

The average kinetic energy of the particles that make up a substance.

What is the first law of thermodynamics in the context of Thermodynamics problems?

The change in the total internal energy of a system must be equal to the change in heat and work (because energy must be conserved). ΔU = q + W Q-W (energy transferred in as heat mine work done by the system)

What is conduction?

The direct transfer of energy from molecule to molecule through physical collisions. Has to be directly touching, cant be anything in between the two objects

What is the third law of thermodynamics?

The entropy of a perfectly organized crystal at absolute zero is zero. This really means that there can be no temperature lower than absolute zero.

What is Entropy?

The extent to which a system is spread out/unorganized. The more spread out/ the less organized the more entropy.

What is the specific heat of a substance?

The heat energy required to raise one gram of a substance by one degree celsius or kelvin.

What is a system in the context of thermodynamics?

The portion of the universe we are interested in observing or manipulating. The rest of the universe is the surroundings.

Explain how something like pressure is a state function.

The pressure in a system is defined only by the current equilibirum state of the gas particles. Take for instance, 2 balloons with a pressure of 1 atm each. The pressures in these balloons are identical. It does not matter if the first balloon came to 1 atm from 10 atm and the second balloon came to 1 atm from .01 atm. The fact of the matter is that, right now, their pressures are both 1 atm.

What is heat?

The process by which energy is transferred between two objects by virtue of their difference in temperature

What is thermal expansion?

The tendency of objects to increase in size with increases in temperature.

What is radiation? How is it unique?

The transfer of energy by electromagnetic waves. Radiation is unique in that it requires no contact whatsoever with a material to exert its effects. In fact, radiation can even transfer energy through a vacuum.

What is convection?

The transfer of heat by the physical motion of a fluid. (plume of smoke over fire is heat rising through air) (Remember, gases and liquids both behave as fluids!) Warm water flowing over an object is convection NOT conduction. Object sitting in still water is conduction.

Explain how something like work is a process function

The work done by or on a system is defined by the path the work took. Work can be calculated using W = Fdcosθ where F is force and d is distance. Therefore, differing path lengths (d) are built into the equation and must be considered. For further elaboration, consider the following. Two weights are at a height of 10 meters. The first weight was brought from 0 meters to a height of 10 meters, which took some amount of work. The second weight, on the other hand, went up 10 m, left 5 meters, and then right 5 meters. Both weights are in the same final position, 10 meters above ground level, but the second case took more work.

What does it mean to be isothermal and how does that affect the first law of thermodynamics equation?

There is no change in temperature (and therefore no change in internal energy --> ΔU =0) Q=W --> system=work done by system

What is the zeroth law of thermodynamics?

When an object x is in thermal equilibrium with an object y, and that object y is in thermal equilibirum with another object z, x will be in thermal equilibrium with z.

When do we give heat positive or negative values?

When heat is entering or leaving the system, respectively.

What is the specific heat equation?

Where c is the specific heat of the substance. *Mass in grams* when using c = 4.184 MNEMONIC: Q=MCAT

What is the equation for the heat of transformation?

Where q is heat, m is the mass of the substance, and L is the heat/g of the phase change in question.

What are the 2 process functions?

mechanical Work and Heat