Exam I Concepts

Convection Current

The flow of a fluid when heat is transferred by convection.

b

Two bars are conducting heat from a region of higher temperature to a region of lower temperature. The bars have identical lengths and cross-sectional areas, but are made from different materials. In the drawing they are placed "in parallel" between the two temperature regions in arrangement A, whereas they are placed end to end in arrangement B. In which arrangement is the heat that is conducted the greatest? image a The heat conducted is the same in both arrangements. b Arrangement A c Arrangement B e It is not possible to determine which arrangement conducts more heat.

Conduction

A process by which heat is transferred through a material without a bulk movement of the material.

Reversible process

A process in which both the system and its environment can be returned to exactly the states they had before the process occurred.

Convection

A process in which heat energy is transferred by the flow of a fluid.

c

A refrigerator operates for a certain time, and the work done by the electrical energy during this time is W=1000J. What can be said about the heat delivered to the room containing the refrigerator? a. The heat delivered to the room is less than 1000 J. b. The heat delivered to the room is equal to 1000 J. c. The heat delivered to the room is greater than 1000 J.

|Q.c|/|Q.H| = T.c/T.H e.Carrot = 1/ T.c/T.H

A reversible process is one in which both the system and its environment can be returned to exactly the states they were in before the process occurred. Carnot's principle is an alternative statement of the second law of thermodynamics. It states that no irreversible engine operating between two reservoirs at constant temperatures can have a greater efficiency than a reversible engine operating between the same temperatures. Furthermore, all reversible engines operating between the same temperatures have the same efficiency. A Carnot engine is a reversible engine in which all input heat originates from a hot reservoir at a single Kelvin temperature and all rejected heat goes into a cold reservoir at a single Kelvin temperature . For a Carnot engine, Equation 15.14 applies. The efficiency of a Carnot engine is the maximum efficiency that an engine operating between two fixed temperatures can have and is given by Equation 15.15.

Atomic mass scale

A scale in which the mass of an atom of one element is compared to the mass of an atom of another element. The reference atom is chosen to be carbon-12, whose atomic mass is defined to be exactly twelve atomic mass units (12 u), where .

Celsius scale

A scientific temperature scale which assigns to the freezing point of water and to the boiling point of water.

Kelvin (absolute) scale

A scientific temperature scale which has the same size degree as the Celsius scale, but assigns the lowest possible temperature as . A degree is called a Kelvin (K) and is the SI unit for temperature. Absolute zero The zero point on the Kelvin temperature scale. It is the lowest possible temperature that can be attained by cooling an object.

b

A solid sphere and a solid cube are made from the same material. The sphere would just fit within the cube, if it could. Both begin at the same temperature, and both are heated to the same temperature. Which object, if either, has the greater change in volume? a. The sphere. b. The cube. c. Both have the same change in volume. d. Insufficient information is given for an answer.

Thermal stress

A stress which develops within an object when it attempts to expand or contract in response to a temperature change, but cannot due to being held rigidly in place.

isochoric, isothermal, adiabatic W = PΔV = P(V.f-V.i)

A thermal process is quasi-static when it occurs slowly enough that a uniform pressure and temperature exist throughout the system at all times. An isobaric process is one that occurs at constant pressure. The work W done when a system changes at a constant pressure P from an initial volume V.i to a final volume V.f is given by Equation 15.2. An _____ process is one that takes place at constant volume, and no work is done in such a process. An _____ process is one that takes place at constant temperature. An _____ process is one that takes place without the transfer of heat. The work done in any kind of quasi-static process is given by the area under the corresponding pressure-volume graph.

system, surroundings, state

A thermodynamic _____ is the collection of objects on which attention is being focused, and the ______ are everything else in the environment. The _____ of a system is the physical condition of the system, as described by values for physical parameters, often pressure, volume, and temperature.

Adiabatic process

A thermodynamic process in which no heat flows into or out of the system.

Isobaric process

A thermodynamic process which occurs at constant pressure.

Isothermal process

A thermodynamic process which occurs at constant temperature.

Isochoric process

A thermodynamic process which occurs at constant volume.

d

All but one of the following statements are true. Which one is not true? a A mass (in grams) equal to the molecular mass (in atomic mass units) of a pure substance contains the same number of molecules, no matter what the substance is. b One mole of any pure substance contains the same number of molecules. c Ten grams of a pure substance contains twice as many molecules as five grams of the substance. d Ten grams of a pure substance contains the same number of molecules, no matter what the substance is. e Avogadro's number of molecules of a pure substance and one mole of the substance have the same mass.

Blackbody

An idealized perfect absorber and perfect emitter of radiation.

Heat engine

Any device that uses heat to perform work.

thermal equilibrium, Temperature

Two systems are in _____ ______ if there is no net flow of heat between them when they are brought into thermal contact. _____ is the indicator of thermal equilibrium in the sense that there is no net flow of heat between two systems in thermal contact that have the same temperature.

R

Universal gas constant = 8.31

e

1. Which one of the following statements correctly describes the Celsius and the Kelvin temperature scales? a The size of the degree on the Celsius scale is larger than that on the Kelvin scale by a factor of 9/5. b. Both scales assign the same temperature to the ice point, but they assign different temperatures to the steam point. c. Both scales assign the same temperature to the steam point, but they assign different temperatures to the ice point. d. The Celsius scale assigns the same values to the ice and the steam points that the Kelvin scale assigns. e. The size of the degree on each scale is the same.

b

2. The drawing shows two thin rods, one made from aluminum and the other from steel . Each rod has the same length and the same initial temperature and is attached at one end to an immovable wall, as shown. The temperatures of the rods are increased, both by the same amount, until the gap between the rods is closed. Where do the rods meet when the gap is closed? a. The rods meet exactly at the midpoint. b. The rods meet to the right of the midpoint. c. The rods meet to the left of the midpoint.

Thermodynamics

A branch of physics built upon the laws which govern the behavior of heat and work.

Forced convection

A convection process in which an external device, such as a fan, is used to produce the fluid flow.

Natural convection

A convection process in which the fluid flows due to buoyant forces produced because the heated fluid is less dense than the surrounding cooler fluid.

Entropy

A function of state that is associated with disorder in the system and environment.

e e = Work done/Input heat = |W|/|Q.H| |Q.H| = |W| + |Q.c| e = 1- |Q.c|/|Q.H|

A heat engine produces work from input heat that is extracted from a heat reservoir at a relatively high temperature. The engine rejects heat into a reservoir at a relatively low temperature. The efficiency _____ of a heat engine is given by Equation 15.11. The conservation of energy requires that must be equal to plus , as in Equation 15.12. By combining Equation 15.12 with Equation 15.11, the efficiency of a heat engine can also be written as shown in Equation 15.13.

c

A monatomic ideal gas is thermally insulated, so no heat can flow between it and its surroundings. Is it possible for the temperature of the gas to rise? a Yes. The temperature can rise if work is done by the gas. b No. The only way that the temperature can rise is if heat is added to the gas. c Yes. The temperature can rise if work is done on the gas.

Phase diagram

A plot of pressure vs. temperature for a given substance showing the various phases possible for that particular substance.

Radiation

A process by which energy is transferred by electromagnetic waves.

m, t, L, A, ΔC, D m = ((DAΔC)t)/L

Diffusion is the process whereby solute molecules move through a solvent from a region of higher solute concentration to a region of lower solute concentration. Fick's law of diffusion states that the mass _____ of solute that diffuses in a time _____ through the solvent in a channel of length _____ and cross-sectional area _____ is given by Equation 14.8, where ____ is the solute concentration difference between the ends of the channel and _____ is the diffusion constant.

molecular mass, n, N, N.A, m, m.particle n= N/NA N = m/Mass per mole m.particle = Mass per mole/NA

Each element in the periodic table is assigned an atomic mass. One atomic mass unit (u) is exactly one-twelfth the mass of an atom of carbon-12. The ______ _____ of a molecule is the sum of the atomic masses of its atoms. The number of moles _____ contained in a sample is equal to the number of particles _____ (atoms or molecules) in the sample divided by the number of particles per mole _____, as shown in Equation 1, where NA is called Avogadro's number and has a value of NA = 6.022 E23 particles per mole. The number of moles is also equal to the mass m of the sample (expressed in grams) divided by the mass _____ per mole (expressed in grams per mole), as shown in Equation 2. The mass per mole (in ) of a substance has the same numerical value as the atomic or molecular mass of one of its particles (in atomic mass units). The mass _____ of a particle (in grams) can be obtained by dividing the mass per mole (in ) by Avogadro's number, according to Equation 3.

b

For an ideal gas, each of the following unquestionably leads to an increase in the pressure of the gas, except one. Which one is it? a Increasing the temperature and decreasing the volume, while keeping the number of moles of the gas constant b Increasing the temperature, the volume, and the number of moles of the gas c Increasing the temperature, while keeping the volume and the number of moles of the gas constant d Increasing the number of moles of the gas, while keeping the temperature and the volume constant e Decreasing the volume, while keeping the temperature and the number of moles of the gas constant.

T, Tc, absolute zero T = Tc + 273.15

For scientific work, the Kelvin temperature scale is the scale of choice. One kelvin (K) is equal in size to one Celsius degree. However, the temperature _____ on the Kelvin scale differs from the temperature Tc on the Celsius scale by an additive constant of 273.15, as indicated by Equation 12.1. The lower limit of temperature is called _____ ______ and is designated as 0 K on the Kelvin scale.

ΔV, Vo, β ΔV= βVoΔT

For volume expansion, the change _____ in the volume of an object of volume _____ is given by Equation 12.3, where _____ is the coefficient of volume expansion. When the temperature changes, a cavity in a piece of solid material expands or contracts as if the cavity were filled with the surrounding material.

diatomic

Has with two molecule ie N2, H2, etc.

b

Heat is transferred from the sun to the earth via electromagnetic waves (see Chapter 24). Because of this transfer, the entropy of the sun ________, the entropy of the earth ________, and the entropy of the sun-earth system ________. a increases, decreases, decreases b decreases, increases, increases c increases, increases, increases d increases, decreases, increases e decreases, increases, decreases

Q, m, L Q=mL

Heat must be supplied or removed to make a material change from one phase to another. The heat ______ that must be supplied or removed to change the phase of a mass _____ of a substance is given by Equation 12.5, where _____ is the latent heat of the substance and has SI units of J/kg. The latent heats of fusion, vaporization, and sublimation refer, respectively, to the solid/liquid, the liquid/vapor, and the solid/vapor phase changes.

β

Intensity level or coefficient of volume expansion

L

Length, latent heat

0E, 1B, 2AD, 3C

Match the laws. Numbers may have more than one letter. All letters used only once 0 Zeroth 1 First 2 Second 3 Third A the total entropy of the universe does not change when a reversible process occurs and increases when an irreversible process occurs B Due to heat and work, the internal energy of a system changes...conservation-of-energy principle applied to heat, work, and the change in the internal energy C It is not possible to lower the temperature of any system to absolute zero in a finite number of steps. D Heat flows spontaneously from a substance at a higher temperature to a substance at a lower temperature and does not flow spontaneously in the reverse direction E That two systems individually in thermal equilibrium with a third system are in thermal equilibrium with each other

Thermal insulators

Materials which conduct heat poorly.

Thermal conductors

Materials which conduct heat well.

Lo, ΔL, ΔT, α, thermal stress ΔL= αLoΔT

Most substances expand when heated. For linear expansion, an object of length _____ experiences a change _____ in length when the temperature changes by _____, as shown in Equation 12.2, where _____ is the coefficient of linear expansion. For an object held rigidly in place, a _____ _____ can occur when the object attempts to expand or contract. The stress can be large, even for small temperature changes. When the temperature changes, a hole in a plate of solid material expands or contracts as if the hole were filled with the surrounding material.

Carnot's principle

No irreversible engine operating between two reservoirs at constant temperatures can have a greater efficiency than a reversible engine operating between the same temperatures.

100, 180

On the Celsius temperature scale, there are _____ equal divisions between the ice point and the steam point . On the Fahrenheit temperature scale, there are _____ equal divisions between the ice point and the steam point .

The Mole and Avogadro's number

One mole of a substance contains as many particles (atoms or molecules) as there are atoms in 12 grams of the isotope carbon-12. There are atoms in 12 grams of carbon-12. The number of atoms per mole is known as Avogadro's number, , where .

c

The first law of thermodynamics states that the change in the internal energy of a system is given by , where Q is the heat and W is the work. Both Q and W can be positive or negative numbers. Q is a positive number if ________, and W is a positive number if ________. a the system loses heat; work is done by the system b the system loses heat; work is done on the system c the system gains heat; work is done by the system d the system gains heat; work is done on the system

coefficient of performance of a refrigerator = |Q.c|/|W| Coefficient of performance of a heat pump = |Q.H|/|W|

Refrigerators, air conditioners, and heat pumps are devices that utilize work to make heat flow from a lower Kelvin temperature to a higher Kelvin temperature . In the process (the refrigeration process) they deposit heat at the higher temperature. The principle of the conservation of energy requires that . If the refrigeration process is ideal, in the sense that it occurs reversibly, the devices are called Carnot devices and the relation (Equation 15.14) holds. The coefficient of performance of a refrigerator or an air conditioner is given by Equation 15.16. The coefficient of performance of a heat pump, however, is given by Equation 15.17.

Ideal gas law

Relates the pressure, volume, and temperature of an ideal gas. It states that where is the number of moles present and R is the universal gas constant.

σ

Stefan-Boltzman constat = 5.67 E-8

T

Temperature

dew point % relativee humidity= (Partial pressure of water vapor)/(Equilibrium vapor pressure of water athe thexisting temperature) x100

The _____ _____ is the temperature below which the water vapor in the air condenses. On the vaporization curve of water, the dew point is the temperature that corresponds to the actual pressure of water vapor in the air.

equilibrium vapor pressure, temperature, temperature, pressure

The _____ ______ ______ of a substance is the pressure of the vapor phase that is in equilibrium with the liquid phase. For a given substance, vapor pressure depends only on _____. For a liquid, a plot of the equilibrium vapor pressure versus temperature is called the vapor pressure curve or vaporization curve. The fusion curve gives the combinations of _____ and ____for equilibrium between solid and liquid phases.

internal energy, Heat, higher, lower

The _____ ______ of a substance is the sum of the kinetic, potential, and other kinds of energy that the molecules of the substance have. _____ is energy that flows from a (lower/higher?)-temperature object to a (lower/higher?)-temperature object because of the difference in temperatures. The SI unit for heat is the joule (J).

Latent heat

The amount of heat energy per kilogram that must be added or removed when a substance changes from one phase to another (i.e., from solid to liquid - heat of fusion, or from liquid to gas - heat of vaporization). The SI unit of latent heat is J/kg.

d

The atomic mass of a nitrogen atom (N) is 14.0 u, while that of an oxygen atom (O) is 16.0 u. Three diatomic gases have the same temperature: nitrogen (N2), oxygen (O2), and nitric oxide (NO). Rank these gases in ascending order (smallest first), according to the values of their translational rms speeds: a O2, N2, NO b NO, N2, O2 c N2, NO, O2 d O2, NO, N2 e N2, O2, NO

ΔS. reversible, Irreversible ΔS = (Q/T).R W.unavailable = TpΔS.universe

The change in entropy _____ for a process in which heat Q enters or leaves a system reversibly at a constant Kelvin temperature T is given by Equation 15.18, where the subscript R stands for "_____." The second law of thermodynamics can be stated in a number of equivalent forms. In terms of entropy, the second law states that the total entropy of the universe does not change when a reversible process occurs and increases when an irreversible process occurs . _____ processes cause energy to be degraded in the sense that part of the energy becomes unavailable for the performance of work. The energy that is unavailable for doing work because of an irreversible process is shown in Equation 15.19, where is the total entropy change of the universe and is the Kelvin temperature of the coldest reservoir into which heat can be rejected. Increased entropy is associated with a greater degree of disorder and decreased entropy with a lesser degree of disorder (more order).

Thermal expansion

The change in physical size (length, area or volume) of a substance when its temperature changes. For most substances, the physical size increases with an increase in temperature and decreases with a decrease in temperature.

Fahrenheit scale

The common temperature scale which assigns to the freezing point of water and to the boiling point of water.

Molar specific heat capacity

The constant, , in the equation which determines the amount of heat lost or gained by moles of a substance when its temperature changes by .

Maxwell speed distribution

The distribution of particle speeds in an ideal gas at a given temperature.

KE, v.rms, U KE = (1/2)mv.rms^2 = (3/2)kT U = (3/2)nRT

The distribution of particle speeds in an ideal gas at constant temperature is the Maxwell speed distribution (see Figure 14.8). The kinetic theory of gases indicates that the Kelvin temperature T of an ideal gas is related to the average translational kinetic energy _____ of a particle, according to Equation 14.6, where is _____ the root-mean-square speed of the particles. The internal energy _____ of n moles of a monatomic ideal gas is given by Equation 14.7. The internal energy of any type of ideal gas (e.g., monatomic, diatomic) is proportional to its Kelvin temperature.

b

The drawing shows the expansion of three ideal gases. Rank the gases according to the work they do, largest to smallest. image a A, B, C b A and B (a tie), C c B and C (a tie), A d B, C, A e C, A, B

Internal energy

The energy associated with individual molecules in a gas, liquid, or solid. This energy may take the form of translational or rotational kinetic energy, vibrational energy, or potential energy.

Heat

The energy that flows from a higher temperature object to a lower temperature object because of the difference in temperatures. The SI unit of heat is the joule (J). Another unit for heat is the calorie (cal) or kilocalorie (kcal).

ΔU, U.i, U.f, gains, loses, by, on, internal energy ΔU = U.f-U.i = Q-W

The first law of thermodynamics states that due to heat Q and work W , the internal energy _____ of a system changes from its initial value of _____ to a final value of _____ according to Equation 15.1. In this equation Q is positive when the system (gains/loses?) heat and negative when it (gains/loses?) heat. W is positive when work is done (on/by?) the system and negative when work is done (on/by?) the system. The first law of thermodynamics is the conservation-of-energy principle applied to heat, work, and the change in the _____ _____, called a function of state because it depends only on the state of the system and not on the method by which the system came to be in a given state.

e

The following statements concern how to increase the rate of diffusion (in ). All but one statement are always true. Which one is not necessarily true? a Increase the cross-sectional area of the diffusion channel, keeping constant its length and the difference in solute concentrations between its ends. b Increase the difference in solute concentrations between the ends of the diffusion channel, keeping constant its cross-sectional area and its length. c Decrease the length of the diffusion channel, keeping constant its cross-sectional area and the difference in solute concentrations between its ends. d Increase the cross-sectional area of the diffusion channel, and decrease its length, keeping constant the difference in solute concentrations between its ends. e Increase the cross-sectional area of the diffusion channel, increase the difference in solute concentrations between its ends, and increase its length

Specific heat capacity

The heat Q per unit mass per degree change in temperature that must be supplied or removed to change the temperature of a substance. The SI unit for specific heat is J/(kg C°).

Q, m, ΔT, c Q = cmΔT

The heat _____ that must be supplied or removed to change the temperature of a substance of mass _____ by an amount _____ is given by Equation 12.4, where _____ is a constant known as the specific heat capacity. When materials are placed in thermal contact within a perfectly insulated container, the principle of energy conservation requires that the amount of heat lost by warmer materials equals the amount of heat gained by cooler materials. Heat is sometimes measured with a unit called the kilocalorie (kcal). The conversion factor between kilocalories and joules is known as the mechanical equivalent of heat: 1 kcal = 4186 joules

d

The heat conducted through a bar depends on which of the following? A. The coefficient of linear expansion B. The thermal conductivity C. The specific heat capacity D. The length of the bar E. The cross-sectional area of the bar a A, B, and D b A, C, and D c B, C, D, and E d B, D, and E e C, D, and E

P, V, n, T, R = 8.31, k = R/N.A PV=nRT PV=NkT P.iV.i=P.fV.f V.i/T.i=V.f/T.f

The ideal gas law relates the absolute pressure _____, the volume _____, the number ____ of moles, and the Kelvin temperature _____ of an ideal gas, according to Equation 14.1, where ____ is the universal gas constant. An alternative form of the ideal gas law is given by Equation 14.2, where N is the number of particles and _____ is Boltzmann's constant. A real gas behaves as an ideal gas when its density is low enough that its particles do not interact, except via elastic collisions. A form of the ideal gas law that applies when the number of moles and the temperature are constant is known as Boyle's law. Using the subscripts "i" and "f" to denote, respectively, initial and final conditions, we can write Boyle's law as in Equation 14.3. A form of the ideal gas law that applies when the number of moles and the pressure are constant is called Charles' law and is given by Equation 14.4., the number n of moles, and the Kelvin temperature T of an ideal gas, according to Equation 14.1, where is the universal gas constant. An alternative form of the ideal gas law is given by Equation 14.2, where N is the number of particles and is Boltzmann's constant. A real gas behaves as an ideal gas when its density is low enough that its particles do not interact, except via elastic collisions. A form of the ideal gas law that applies when the number of moles and the temperature are constant is known as Boyle's law. Using the subscripts "i" and "f" to denote, respectively, initial and final conditions, we can write Boyle's law as in Equation 14.3. A form of the ideal gas law that applies when the number of moles and the pressure are constant is called Charles' law and is given by Equation 14.4.

monatomic, diatomic, C.p = (7/2)R, C.v.=(5/2)R Q = CndT C.p-C.v = R EDIT THIS MORE>

The molar specific heat capacity C of a substance determines how much heat Q is added or removed when the temperature of n moles of the substance changes by an amount , according to Equation 15.6. For a _____ ideal gas, the molar specific heat capacities at constant pressure and constant volume are given by Equations 15.7 and 15.8, respectively, where R is the ideal gas constant. For a _____ ideal gas at moderate temperatures that do not allow vibration to occur, these values are _____ and _____. For any type of ideal gas, the difference between C.p and C.v is given by Equation 15.10.

n

The number of moles contained in a sample

thermometric

The operation of any thermometer is based on the change in some physical property with temperature; this physical property is called a _____ property. Examples of these properties properties are the length of a column of mercury, electrical voltage, and electrical resistance.

State of the system

The physical condition of the system which is usually described by specifying the pressure, volume and temperature.

Equilibrium vapor pressure

The pressure of the vapor phase of a substance that is in equilibrium with the liquid or solid phase. Vapor pressure depends only on temperature.

a

The pressure-volume graph shows three paths in which a gas expands from an initial state A to a final state B. The change in internal energy is the same for each of the paths. Rank the paths according to the heat Q added to the gas, largest to smallest. image a 1, 2, 3 b 1, 3, 2 c 2, 1, 3 d 3, 1, 2 e 3, 2, 1

Diffusion

The process whereby solute molecules move from a region of higher concentration to a region of lower concentration.

Thermal equilibrium

The state of two or more systems in thermal contact when no heat flows between them. Systems are in thermal equilibrium when they are at the same temperature.

Internal energy

The sum of the various kinds of energy that the atoms or molecules of a substance possess. This includes translational and rotational kinetic energy, vibrational energy, and potential energy.

Kinetic theory of gases

The theory which states that the temperature of an ideal gas is defined by the average kinetic energy of the particles making up the gas.

c

Three cubes are made from the same material. As the drawing indicates, they have different sizes and temperatures. Rank the cubes according to the radiant energy they emit per second, largest first. image a A, B, C b A, C, B c B, A, C d B, C, A e C, B, A

Diathermal walls

Walls which separate a system and the environment and allow heat to flow through them.

Adiabatic walls

Walls which separate the system and environment and do not allow heat to flow through them.

ƴ = C.p/C.v W = nRTln(V.f/V.i) W = (3/2)nR(T.i-T.f) (P.iV.i)^ƴ = (P.fV.f)^ƴ

When n moles of an ideal gas change quasi-statically from an initial volume to a final volume at a constant Kelvin temperature T , the work done is given by Equation 15.3, and the process is said to be isothermal. When n moles of a monatomic ideal gas change quasi-statically and adiabatically from an initial temperature to a final temperature , the work done is given by Equation 15.4. During an adiabatic process, and in addition to the ideal gas law, an ideal gas obeys Equation 15.5, where is the ratio of the specific heat capacities at constant pressure and constant volume.

e

Which of the following cases (if any) requires the greatest amount of heat? In each case the material is the same. a. 1.5 kg of the material is to be heated by 7 C. b. 3.0 kg of the material is to be heated by 3.5 C. c. 0.50 kg of the material is to be heated by 21 C. d. 0.75 kg of the material is to be heated by 14 C. e. The amount of heat required is the same in each of the four previous cases.

a

Which of the following three statements concerning relative humidity values of 30% and 40% are true? Note that when the relative humidity is 30%, the air temperature may be different than it is when the relative humidity is 40%. A. It is possible that at a relative humidity of 30% there is a smaller partial pressure of water vapor in the air than there is at a relative humidity of 40%. B. It is possible that there is the same partial pressure of water vapor in the air at 30% and at 40% relative humidity. C. It is possible that at a relative humidity of 30% there is a greater partial pressure of water vapor in the air than there is at a relative humidity of 40%. a A, B, and C b Only A and B c Only A and C d Only B and C e Only A

Radiation, perfect blackbody, Q, t, A, T, σ, e, net radiant power

_____ is the process in which energy is transferred by means of electromagnetic waves. All objects, regardless of their temperature, simultaneously absorb and emit electromagnetic waves. Objects that are good absorbers of radiant energy are also good emitters, and objects that are poor absorbers are also poor emitters. An object that absorbs all the radiation incident upon it is called a _____ _____ (being a perfect absorber, is also a perfect emitter). The radiant energy _____ emitted during a time _____ by an object whose surface area is _____ and whose Kelvin temperature is _____ is given by the Stefan-Boltzmann law of radiation (see Equation 13.2), where _____ = 5.67 E-8 is the Stefan-Boltzmann constant and is _____ the emissivity, a dimensionless number characterizing the surface of the object. The emissivity lies between 0 and 1, being zero for a nonemitting surface and one for a perfect blackbody. The _____ ______ ______ is the power an object emits minus the power it absorbs. The net radiant power emitted by an object with a temperature located in an environment with a temperature is given by Equation 13.3.

Convection, Forced

_____ is the process in which heat is carried from place to place by the bulk movement of a fluid. During natural convection, the warmer, less dense part of a fluid is pushed upward by the buoyant force provided by the surrounding cooler and denser part. _____ convection occurs when an external device, such as a fan or a pump, causes the fluid to move.

Conduction, thermal conductors, thermal insulators, Q, t, L, A, ΔT, k Q = (kAΔT)/L

_____ is the process whereby heat is transferred directly through a material, with any bulk motion of the material playing no role in the transfer. Materials that conduct heat well, such as most metals, are known as _____ _____. Materials that conduct heat poorly, such as wood, glass, and most plastics, are referred to as _____ ______. The heat _____ conducted during a time _____ through a bar of length _____ and cross-sectional area _____ is given by Equation 13.1, where _____is the temperature difference between the ends of the bar and _____ is the thermal conductivity of the material.

P

absolute pressure

α

coeficient of linear expansion

monoatomic

composed of single atoms

D

diffusion constant

e

emmissivity

S

entropy

Q

heat, radiant energy

e

ideal monatomic gas expands isothermally from A to B, as the graph shows. What can be said about this process? image a The gas does no work. b No heat enters or leaves the gas. c The first law of thermodynamics does not apply to an isothermal process. d The ideal gas law is not valid during an isothermal process. e There is no change in the internal energy of the gas.

U

internal energy

|Q.H|

magnitude o input heat

|Q.c|

magnitude of rejected heat

|W|

magnitude of work

m

mass

N

number of particles (atoms or molecules) in the sample

ƴ

ratio of the specific heat capacities at constant pressure and constant volume = C.p/C.v

v.rms

root-mean-square of particles

ΔC

solute concentration difference

c

specific heat capacity

e.Carrot

the maximum efficiency that an engine operating between two fixed temperatures