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What is true of the relationship between intermolecular forces of a molecular substance and it's boiling point?A substance with weak intermolecular forces will have a low boiling point.
A substance with strong intermolecular forces will require more energy to separate the molecules so that they can enter the vapor phase.An increase in the temperature of a substance will _____ the fraction of molecules that have enough kinetic energy to escape liquid phase and will therefore cause a(n) _____ in the vapor pressureIncrease, increaseA substance with weaker intermolecular forces vaporizes more easily and....Has a high vapor pressureWhat is the strongest type of dipole bondion dipoleWhat is dispersionA solution isa homogeneous mixture meaning it exists in a single phaseColloidheterogeneous two or more phasesWhat is misciblecan dissolve in any proportionDual PolarityThe boiling point of a substance is the temperature at which the vapor pressure of the substance is ___________ the external pressureequal toA physical state of matter that is chemically and physically uniform is called a(n) _____.
Multiple choice question.PhaseIn a molecular substance, the covalent bonds between the atoms hold the individual molecule together as a unit and are referred to as _____ forces. The nonbonding forces of attraction between one individual molecule and another are called _____ forces. The physical behavior of the phases of matter reflect the difference in the strength of their _____.
Multiple choice question.intramolecular; intermolecular; intermolecular forcesWhich of the following options correctly describe the phases of matter in terms of kinetic molecular theory? Select all that apply.The particles of a liquid have enough kinetic energy to move randomly past each other, allowing the liquid to flow.
A liquid occupies a fixed volume because the particles are held together by appreciable attractive forces.
In the solid phase, forces of attraction dominate over the movement of particles.At _____ temperatures the forces of attraction between particles dominate because the particles are moving slowly. At _____ temperatures the movement of the particles overcomes the attractions.
Multiple choice question.Lower;HigherCondensation, freezing, and deposition are _____ phase changes, whereas melting, vaporization, and sublimation are _____ changes.
Multiple choice question.exothermic; endothermicWhich of the following statements correctly describe bonding and intermolecular forces? Select all that apply.For a molecular substance, the strength of the intermolecular forces determines the physical properties of its phases.
Intermolecular forces involve partial or small charges that are far apart and are relatively weak.
Bonding forces are generally much stronger than intermolecular forcesHalf the distance between the nuclei of two covalently bonded atoms is the ______, whereas half the shortest distance between the nuclei of identical nonbonded atoms is the ______.covalent radius; van der Waals radiusion-dipole forces_ involve the attraction between an charged particle and a nearby polar molecule. The most common example of such an intermolecular force of attraction is the dissolution of an ionic compound by water.Which of the following structural features would allow a molecular substance to exhibit hydrogen bonding between its molecules? Select all that apply.One or more O-H bonds
One or more N-H bondsWhich of the following statements correctly describe dipole-dipole forces? Select all that apply.Dipole-dipole forces are the forces of attraction between two polar molecules.
For two compounds of similar molar mass, the greater the molecular dipole moment, the stronger the dipole-dipole forces.Which of the following options correctly defines polarizability?
Multiple choice question.This is a measure of how the electron cloud around an atom responds to its electronic environment.True or false: Dispersion forces are exhibited only by nonpolar molecules.FalseAs the boiling point graph shows, H2O, NH3, and HF deviate from the boiling point trend shown for the hydrides of the carbon group. Select the statement that correctly explains this deviation.
Multiple choice question.The H bonding between molecules of H2O, NH3, and HF is much stronger than the intermolecular forces between CH4 molecules.Which of the following statements correctly describe dispersion or London forces? Select all that apply.Dispersion forces are a weak attraction between temporary dipoles.
All covalent compounds exhibit dispersion forces.Which of the following options correctly reflect the relationship between dispersion forces and particle size? Select all that apply.Larger particles are more polarizable and experience stronger dispersion forces.
For molecules of similar shape, dispersion forces tend to increase with increasing molar mass.Which statement correctly explains how polarizability affects intermolecular forces?
Multiple choice question.A more polarizable molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overall.The larger a molecule or atom, the _____ the number of electrons and the _____ polarizable it will generally be. The strength of the dispersion forces for a particular substance therefore generally _____ as molar mass increases, providing molecules of similar shape are comparedgreater; more; increasesWhich option correctly reflects the relationship between molecular shape and the strength of dispersion forces?Molecules with a large surface area have more points of contact and therefore experience stronger dispersion forces.Which of the following statements correctly describe the surface tension of a liquid? Select all that apply. (Assume the liquid is a molecular substance.)Surface tension is the result of a net downward and inward force on the surface particles of a liquid.
A polar liquid will have a higher surface tension than a nonpolar liquid.
Surface tension is the amount of energy required to increase the surface area of a liquid by a unit areaMolecules with a larger surface area have _____ points of contact between them than molecules with less surface area. This leads to _____ dispersion forces overall.
Multiple choice question.More; StrongerA liquid rises against the pull of gravity through a narrow space through capillary action. This results from a competition between the _____ intermolecular forces between the molecules of the liquid itself and the _____ forces between the liquid and the walls of the container.
Multiple choice question.Cohesive; AdhesiveViscosityResistance of fluid to flowThe surface tension of a liquid, the energy required to increase the surface area by a given amount, is dependent on ______ and ______. Select all that apply.Intermolecular forces
TemperatureH2O exhibits extremely strong and efficient hydrogen bonding between its molecules. Which of the following properties result from this behavior? Select all that apply.High surface tension
High specific heat capacity
High capillaritySelect the correct description of capillary action.The rising of a liquid through a narrow space against gravityWhich of the following statements correctly describe the viscosity of a liquid? Select all that apply.A liquid with stronger intermolecular forces will have a higher viscosity.
The viscosity of a given liquid decreases with increasing temperature.
Viscosity is a liquid's resistance to flow.Which of the following statements correctly describe the surface tension of a liquid? Select all that apply. (Assume the liquid is a molecular substance.)A polar liquid will have a higher surface tension than a nonpolar liquid.
Surface tension is the amount of energy required to increase the surface area of a liquid by a unit area.
Surface tension is the result of a net downward and inward force on the surface particles of a liquid.Since H2O is able to exhibit different types of intermolecular forces including hydrogen bonding, this substance has a _____ heat capacity and a _____ heat of vaporization compared to other liquids.High; HighWater is unique in the way it behaves as a wonderful solvent of many substances. Which of the following is NOT correct?
Multiple choice question.H2O dissolves metals through metallic bond seperationAnswer Mode
Multiple Select QuestionYour Answer correct
Water is often called the "universal solvent" because of its ability to dissolve so many substances. Select the means by which water behaves as a solvent. Select all that apply.Water dissolves nonpolar gases somewhat through dipole-induced dipole interactions.
Water dissolves ionic compounds through such strong ion-dipole forces that ions separate from their lattices and stay in solution.
Water dissolves polar substances through hydrogen bonding or dipole-dipole attractions.Water has a very high specific heat capacity compared to other common liquids. This property is due to ______ water.Strong hydrogen bonding inThe high capillary action of water is a result of its ______.strong hydrogen bondingThe resistance of large bodies of water to changes in temperature with the input of energy (typically radiant solar energy) is a result of water's ___high specific heat of vaporizationSurface tensiobDebris and bugs readily float on the surface of water because it has the highest ______ of any liquid except for some molten metals and salts.Ice contains a very open structure due to the arrangement of H bonds. Liquid water is more dense than ice because H bonds ______, allowing a much tighter packing arrangement of molecules.
Multiple choice question.Are more randomThe molar enthalpy of sublimation of a given substance can be determined if its enthalpies of fusion and vaporization are knownTrueWhich equation should be used to calculate the heat change when a given mass of H2O is heated from 15*C to 95*C?q= m*s*deltaTSolve for the enthalphy change when 45.1g of H2O changes from gas to the liquid phase at 1008c, deltaH vap= 40.7kJ, s = 33.1 J/mol*kq=(45.1g/18.0153g/mol)*(-40.7kJ) = -102 kJselect all statements that describe molar heat of vaporizationBoth the boiling point and delta H vap of a molecular substance are related to the strength of the intermolecular forces
Delta H vap is the amount of heat required to vaporize 1 mol of a substance at its boiling point
Delta H vap is a positive quantityIntermolecular forces influence the vapor pressure of a substance. The ____ the intermolecular forces, the more tightly the molecules are held together, and the ____ the amount of energy required for them to break free of the liquid phaseStronger; GreaterThe temp above which a gas cannot be liquefied by increasing the pressure on it is called its ____ temperature. A fluid at a temperature and pressure above Tc and Pc is called a ____ fluidCritical; SupercriticalThe molar heat of ____ is the amount of energy required to melet 1 mole of solid. the energy change that occurs when 1 mole of liquid freezes is ____ in magnitude but ____ in signFusion; Equal; OppositeA heating curve shows the changes in ____ that occur when ____ is added or removed from a sample of waterTemperature; HeatWhich statement correctly describes the process of melting point of a substance?At the melting point of a substance, the solid and liquid phases are in equilibriumWhich correctly describes a heating-cooling curve/A plot of heat vs temperature for a substance that is heated or cooled at a constant rate and constant pressureMatch the effect of heating/cooling a substance to the change in temp that occursWithin a phase: heat change causes a temperature change
During a phase change: Heat is added or removed but temperature remains the sameWhich correctly describes the bonding in graphite?Graphite consists of flat sheets or layers of covalently bonded carbon atoms
The pi bonds electrons in graphite are delocalized, allowing graphite to conduct electricityA sample containing 25g liquid diethyl ether is cooled from 25.5*C to 3.5*C. the substance remains in the liquid phase. Select all the options that correctly reflect the calculations needed to determine qThe sample contains 3.337X10^-2 mol diethyl ether
q=-0.13 kJGiven the following information, what is the enthalphy change when 54.5 g of water vapor is heated from 100*C to 200*C54.5g*(1mol/18.02g) = 100X10^4J
q = 3.02 X 33.1 * 100If heat is removed rapidly from a liquid the particles will have no time to adopt the ordered arrangement of a solid. The resulting ____ liquid will be unstableSupercooledThe triple point is represented on a phase diagram to show when all 3 ____ of a substance are at ____Phases; EquilibriumWhich of the following statements correctly describe the critical temperature and pressure of a substance?At the critical point of a substance the densities of the liquid and gas phases are equal
At temperatures and pressures above the critical point in a substance exists as a supercritical fluidUnlike most other substances, the density of solid H2O is ____ than the density of the liquid; hence water ____ when it freezes. This is reflected in the phase diagram for H2O. The solid-liquid boundary line has a negative slope, which reflects the fact that the higher the pressure, the ____ the temperature at which the water freezesLower; Expands; LowerA phase diagram is a plot of ____ on the x-axis vs. ____ on the y-axis. This diagram shows the stable regions for each ____ of matter and the conditions under which these may exist in equilibriumTemperature; Pressure; PhaseAs the temperature of a substance increases, the average ______energy of its particles also increase, and movement overcome forces of _____ more easily. As temperature decrease, particles move more slowly, and the _____ forces between particles dominatekinetic,
attraction,
attractiveFor a given material, its enthalpy of fusion is typically much lower than its enthalpy of vaporization because ________.ΔHvap is the energy required to separate particles completelyCondensation, freezing, and deposition are _____ phase changes, whereas melting, vaporization, and sublimation are _____ changes.exothermic; endothermic
Reason:
Condensation, freezing, and deposition are phases in which intermolecular attractions overcome movement. These changes require the release of heat energy as kinetic energy decreases. Melting, vaporization, and sublimation require heat energy to be absorbed in order for kinetic energy to increase and overcome intermolecular attractions.A physical state of matter that is chemically and physically uniform is called a(n) _____.phase
Reason:
A phase change is the conversion of one phase to another. The physical state of matter that is chemically and physically uniform is simply a phase, not a phase change.In a molecular substance, the covalent bonds between the atoms hold the individual molecule together as a unit and are referred to as _____ forces. The nonbonding forces of attraction between one individual molecule and another are called _____ forces. The physical behavior of the phases of matter reflect the difference in the strength of their _____.intramolecular; intermolecular; intermolecular forcesAt _____ temperatures the forces of attraction between particles dominate because the particles are moving slowly. At _____ temperatures the movement of the particles overcomes the attractions.lower; higherWhich of the following correctly describes a heating-cooling curve?A plot of heat vs. temperature for a substance that is heated or cooled at a constant rate and constant pressure
Reason: A heating-cooling curve is constructed by adding or removing heat at a constant rate. The temperature may or may not change, depending on what is happening to the substance.In general, ΔHofus is _____ than ΔHovap for a given substance because it takes _____ energy to overcome the forces holding the molecules in fixed positions (i.e., melt the substance) than to separate the molecules completely from each other (i.e., vaporize the substance).
Multiple choice question.lower; lessMatch each phase change correctly to the term used to describe the process.
Gas → Liquid
Liquid → Solid
Solid → Gas
Liquid → Gas
Solid → Liquid
Gas → SolidCondensation
Freezing
Sublimation
Vaporization
Melting/Fusion
DepositionWhich of the following correctly defines a phase of matter?A physical state that is physically distinct and homogeneousWhich equation should be used to calculate the heat change when a given molar amount of H2O is heated from 15oC to 95oC?q = nCΔTMatch each statement about forces of attraction to the correct description.
Covalent bonds are classified as
matches
Intermolecular forces
The physical state of a molecular substance at a particular temperature and pressure depends on the strength of its
matches
A change in the physical state of a molecular substance does NOT involve the breaking ofintramolecular forces
are the forces of attraction between one individual molecule and another
intermolecular forces
covalent bondsA heating cooling curve shows the changes that occurs when ____ is added to or removed from a sample of matter at a _____ rateHeat, constant,Match each equation for calculating heat lost or gained (q) during a process to its correct application.
Heating or cooling within a phase if moles are given
Heating or cooling during a phase change
Heating or cooling within a phase if mass is givenq = nCΔT
q = nΔHchange
q = mcΔTWhich of the following options correctly describes a phase equilibrium?At equilibrium, the amount of the substance in each phase remains constant.
If the rate of condensation is equal to the rate of evaporation, a phase equilibrium exists.
A system must be closed in order for a phase equilibrium to be established.Match each lettered portion of the following heating curve to the correct description.
p
s
q
r
tThe substance is in the solid phase.
The substance is changing from liquid to vapor.
Both solid and liquid phases are present.
The kinetic energy of the liquid particles is increasing.
The particles are far apart and movement dominates the phase.Which of the following statements correctly describe vapor pressure?The vapor pressure is the pressure exerted by the vapor above a liquid at equilibrium.
The vapor pressure of a molecular substance depends on the strength of its intermolecular forces.
Vapor pressure increases as temperature increases.The phase changes of many substances are reversible and a phase change, just like a chemical reaction, may reach ___providing it takes place in a(n)___system.Equilibrium , ClosedThis equation is used for the phase change from liquid to gas.q = nΔHovapA combination of q = nCΔT and q = nΔHvap is..No phase change occurs in this temperature range, so the molar heat of vaporization will not be used.This equation is used for the phase change from gas to liquid.q = -nΔHovapThe vapor pressure of a given molecular substance is affected by changes in ________ and by the strength of the _______ forces for the substance.temperature, intermolecularThe pressure exerted by the _____ above a liquid at the equilibrium is called the equilibrium ______ pressure. this pressure ______ as the temperature of the system increases.vapor, vapor, increasesAn increase in temperature will cause the vapor pressure of a substance to _____.increaseIf a molecular substance has strong intermolecular forces, the molecules at the surface of the liquid are held _____ tightly and vaporize _____ easily than molecules with weaker intermolecular forces. The amount of substance in the vapor phase will be _____ than for molecules with weak intermolecular forces and the vapor pressure will therefore be _____.more, less, less, lowerWhich of the following options correctly describe the boiling point of a substance?-The boiling point of a substance increases as the external pressure increases.-The boiling point is the temperature at which the vapor pressure equals the external pressure.-Boiling occurs when the vapor pressure of the liquid is sufficient for bubbles of vapor to form in the interior of the liquid.(Notes:-A liquid can evaporate at any temperature. There will always be some molecules in the liquid with enough energy to escape into the vapor phase. The boiling point is specifically defined as the temperature at which the vapor pressure of the liquid equals the external pressure.-If the external pressure increases the substance will have to be heated to a higher temperature so that its vapor pressure can increase to equal the external pressure.)Which of the following will affect the vapor pressure of a pure molecular substance?the temperature
the strength of the intermolecular forces
the structure of the substanceIf the external pressure on a liquid is increased, the vapor pressure of the liquid must _____ in order for the liquid to boil. The molecules of the liquid require _____ kinetic energy so that more of them can escape the liquid phase. The boiling point of the liquid is therefore _____ when the external pressure is increased.increase, more, higherIntermolecular forces influence the vapor pressure of a substance because the _____ the forces, the more tightly the molecules are held together and the _____ the amount of energy that must be supplied to allow them to break free from the liquid phase.stronger
greaterThe ______ represents the conditions of pressure and temperature where solid, liquid, and gas phases are stable.triple pointAn increase in the temperature of a substance will _____ the fraction of molecules that have enough kinetic energy to escape the liquid phase and will therefore cause a(n) _____ in the vapor pressure.increase; increaseWhich statement correctly describes the relationship between intermolecular forces and the vapor pressure of a substance?A substance with weaker intermolecular forces vaporizes more easily and has a high vapor pressure.Which of the following statements correctly describe bonding and intermolecular forces?Bonding forces are generally much stronger than intermolecular forces.
For a molecular substance, the strength of the intermolecular forces determines the physical properties of its phases.
Intermolecular forces involve partial or small charges that are far apart and are relatively weak.The boiling point of a substance is the temperature at which the vapor pressure of the substance is _____ the external pressure; hence the boiling point depends on the applied pressure.equal to_____ involve the attraction between an charged particle and a nearby polar molecule. The most common example of such an intermolecular force of attraction is the dissolution of an ionic compound by water.Ion-dipole forcesWhich of the following statements correctly describes the relationship between the boiling point of a substance and the external pressure?At a lower external pressure, the molecules of the substance require less energy to form bubbles of vapor and the boiling point is lower.Which of the following statements correctly describe dipole-dipole forces? Select all that apply.Dipole-dipole forces of attraction between two polar molecules
For two compounds of similar molar mass, the greater the molecular dipole moment, the stronger the dipole-dipole forces.The triple point is represented on a phase diagram to show when all three_____of a substance are at______phases or states
equilibrium or dynamic equilibriumWhich of the following statements correctly interpret the phase diagram shown? Select all that apply.The normal boiling point of this substance is 135oC.
The arrow marked 1 represents a change from the solid to the liquid phase.Bonding forces include ionic bonds, metallic bonds, and______ bonds. These types of forces are much_______ than_the forces of attraction between individual molecules, which are called _______forces.-covalent
-stronger
-intermolecularTrue or false: A compound containing one or more oxygen atoms is not necessarily capable of forming hydrogen bonds between its molecules.True
Reason:
The presence of oxygen alone is not sufficient to allow a compound to form hydrogen bonds between its molecules. In addition to oxygen, the compound must have a hydrogen atom capable of hydrogen bonding, i.e., a hydrogen atom covalently bonded to N, O, or F.The attraction between an ion and a nearby polar molecule is called an ion -_____ interaction. This attractive force is important when a(n)____ compound dissolves in a polar solvent such as H2O.dipole, ionicWhen hydrogen is covalently bonded to______ , oxygen, or fluorine there will be an attraction between such a hydrogen and a(n) _________pair of electrons on a nitrogen, oxygen, or fluorine atom on an adjacent molecule. This attraction is called a(n)_______ bond, and it is the strongest type of intermolecular force between neutral species.nitrogen
lone
hydrogenwhen two polar molecules are close to each other they will orient themselves so that the positive pole of one molecule attracts the ________ pole on the adjacent molecule. These intermolecular forces are called __________________ forcesnegative
dipole-dipoleWhich of the following structural features would allow a molecular substance to exhibit hydrogen bonding between its molecules?-one or more O-H bonds-
one or more N-H bondsWhich of the following statements correctly explain why hydrogen bonding requires that H should be covalently bonded to N, O, or F?These elements are small, allowing their lone pairs to approach the H of an adjacent molecule closely.
N, O, and F are so electronegative that a H covalently bonded to any one of these elements has very high positive character.True or false: A bond between O and H within any molecule is called a hydrogen bond.False
Reason:
Correct. A hydrogen bond is an intermolecular attraction between a hydrogen atom and a lone pair of electrons on an O, N, or F atom in another molecule or a different part of the same molecule. A hydrogen bond cannot exist between two atoms that are already covalently bonded to each other. To participate in hydrogen bonding a hydrogen atom must be covalently bonded to N, O, or F.Which of the following options correctly defines polarizability?This is a measure of how the electron cloud around an atom responds to its electronic environment.True or false: Dispersion forces are exhibited only by nonpolar molecules.False
Reason:
Correct. Dispersion forces are experienced by ALL particles (atoms, ions, and molecules). Dispersion forces are, however, the only intermolecular force experienced by nonpolar molecules and atoms.Which of the following statements correctly describes dispersion or London forces? Select all that apply.
a) dispersion forces are stronger for smaller molecules
b) dispersion forces are the primary intermolecular force exhibited by polar molecules
c)all covalent compounds exhibit dispersion forces
d) dispersion forces are a weak attraction between temporary dipolesc) all covalent compounds exhibit dispersion forces
d) dispersion forces are a weak attraction between temporary dipolesFluorine, nitrogen, and oxygen are essential to hydrogen bonding because these elements from the top right portion of the periodic table are so ______ and so ______.electronegative; smallThe term _____ is used to describe how well the electron cloud around an atom responds to changes in its electronic environment.
Multiple choice question.The term _____ is used to describe how well the electron cloud around an atom responds to changes in its electronic environment.polarizability"polarization"implies a permanent unequal distribution of charge in a bond or molecule, while polarizability describes the ability of an electron cloud to shift in response to its environment, enhancing or inducing polarity.Polaritydescribes the existence of a permanent unequal distribution of charge in a bond or molecule, while polarizability describes the ability of an electron cloud to shift in response to its environment, enhancing or inducing polarity.All particles experience_____ forces, a weak attraction that results from induced electron cloud distortion. These forces increase the overall attraction between particles. The more polarizable a particle is, the ______this effect will be.dispersion, strongerWhen two polar molecules are close to each other they will orient themselves so that the positive pole of one molecule attracts____ the pole on the adjacent molecule. These intermolecular forces are called_____ -____ forces.negative
dipole-dipole forcesThe larger a molecule or atom, the ___ the number of electrons and the ___ polarized it will generally be. The strength of the dispersion forces for a particular substance therefore generally ___ as molar mass increases, providing molecules of similar shape are compared.greater, more, increasesDispersion forces are the only type of intermolecular force exhibited by atoms and by ______ molecules. Without the existence of dispersion forces, such substances could not exist in the _______ states of matter.Nonpolar; condensed.Which option correctly reflects the relationship between molecular shape and the strength of dispersion forces?molecules with a large surface area have more points of contact and therefore experience stronger dispersion forcesA momentary change in the electron density surrounding an atom or a molecule causes it to have a(n)_____ dipole even if it is not normally polar. This induces a similar effect in a nearby molecule or atom, and there will be a weak attraction between the two particles as a result. These weak interactions are called ______forces or London forces.instantaneous
dispersionWhich statement correctly explains how polarizability affects intermolecular forces?A more polarizable molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overall.Which intermolecular forces are exhibited between molecules of the compound shown?Dipole-dipole forces
Dispersion forceswhich of the following correctly reflect the relationship between dispersion forces and particle size?-for molecules of similar shape, dispersion forces tend to increase with increasing molar mass
-larger particles are more polarizable and experience stronger dispersion forcesWhich of the following statements correctly describes the hydrogen-bonding capabilities of the water molecule?The magnitude of ΔEN of the O-H bond is very large.
The oxygen atom has two lone pairs with which to form H bonds on neighboring molecules.
The bent geometry of the water molecule makes it very polar.Molecules with a larger surface area have _____ points of contact between them than molecules with less surface area. This leads to _____ dispersion forces overall.more, strongerH2O exhibits extremely strong and efficient hydrogen bonding between its molecules. What is the result of this behavior?1. High capillarity
2. High specific heat capacity
3. High surface tensionWhich of the following statements correctly describe dispersion or London forces?all covalent compounds exhibit dispersion forces
dispersion forces are a weak attraction between temporary dipolesWhat principal intermolecular force keeps these molecules together?
CH3OH
CH3F
C3H8
CaCl2CH3OH-hydrogen bonding
CH3F-dipole dipole
C3H8-dispersion
CaCl2-ionic bondingThe H2O molecule has ____ covalent O-H bonds and ______ , lone pairs on the oxygen atom. This means that each H2O molecule can form a maximum of _______ , H bonds with neighboring H2O molecules. The hydrogen bonding in H2O is therefore very effective.two
two
fourSince H2O is able to exhibit different types of intermolecular forces including hydrogen bonding, this substance has a _____ heat capacity and a _____ heat of vaporization compared to other liquids.high, highA physical state of matter that is chemically and physically uniform is called a(n)phaseEnergy of motion is high compared to the attraction between particles; particles are far apart.gasEnergy of movement is low compared to the attraction between particles; particles remain fixed in position relative to each other.solidThe forces of attraction between particles are appreciable; fixed volume; freedom of movement allows fluidity.liquidCovalent bonds are classified asIntramolecular forcesIntermolecular forcesThe forces of attraction between one individual molecule and another.The physical state of a molecular substance at a particular temperature and pressure depends on the strength of itsIntermolecular forcesA change in the physical state of a molecular substance does NOT involve the breaking ofcovalent bondsAt ___ temperature the forces of attraction between particles dominate because the particles are moving slowly. At ___ temperatures the movement of the particles overcomes the attractions.lower, higherFor a molecular substance, the ___ energy in the form of intermolecular forces tends to draw molecules together. The __ energy associated with the movement of the molecules tends to disperse them. The relative strength of these two effects determines the behavior of the phase of matter.potential, kineticGas to LiquidCondensationLiquid to SolidFreezingSolid to GasSublimationLiquid to GasVaporizationSolid to LiquidMelting/FusionGas to SolidDepositionDelta H(vap)Liquid to Gas- Delta H(fus)Liquid to SolidDelta H(subl)Solid to GasDelta H(fus)Solid to LiquidDescribe a heating cooling curveA plot of heat vs. temperature for a substance that is heated or cooled at a constant rate and constant pressure.Given the following information, what is the enthalpy change when 54.5 g of water vapor is heated from 100.0C to 200.0C (C(gas)=33.1J/mol*K and Delta H(vap) =40.7 kJ/mol)+1.00 * 10^4 J
54.5g*1mol/18.02
q=3.02*33.1*100Within a phase, a change in heat causes the temperature of the substance to ___ as the ___ energy of the molecules changes. During a phase change, however, a change in heat causes a change in the ___ energy of the molecules and the temperature will___.change, kinetic, potential, stay the sameCalculate the enthalpy change when 1.75 moles of diethyl ether changes from the liquid to the gas phase if Delta H(vap)=27.3 kJ/mol and C(liquid)=172 J/mol*K for this substance+47.8 kJ
The sign must be positive because the process is endothermicWhich equation should be used to calculate the heat change when a given molar amount of H2O is heated from 15C to 95Cq=n C deltaTa 25.0g sample of ice at -6.5C is removed from the freezer and allowed to warm until it melts. Given the data below, what reflects the calculations needed to determine the total heat change for this process.
Melting point at 1atm=0.0C; c(solid)=2.09J/g*degreesC; DeltaH(fus)=6.02 kJ/molq for the phase change is given by 1.39*6.02=8.37kJ
25g*1mol/18.02g=1.39mol and
q=nDeltaH(fus)=1.39*6.02=8.37
The total heat change for the process is equal to +8.71kJ
q1=25.0*2.09*6.5=340J or 0.34kJ and
q2=1.39*6.05=8.37kJDescribe equilibrium1. If the rate of condensation is equal to the rate of evaporation, a phase equilibrium exists.
2. At equilibrium, the amount of the substance in each phase remains constant.
3. A system must be closed in order for a phase equilibrium to be established.If a liquid is placed in a closed container, molecules with sufficient ___will move from the liquid to the gas phase. Gas phase molecules will in turn condense. Eventually the ___ of evaporation and condensation will be equal and the system is said to have reached phase___.energy, rates, equilibriumDescribe vapor pressure1. Vapor pressure increases as temperature increases.
2. The vapor pressure is the pressure exerted by the vapor above a liquid at equilibrium.
3. The vapor pressure of a molecular substance depends on the strength of its intermolecular forces.The vapor pressure of a given molecular substance is affected by changes in ___ and by the strength of the ___ forces for the substance.temperature, intermolecularAn increase in the temperature of a substance will___ the fraction of molecules that have enough kinetic energy to escape the liquid phase and will therefore cause a(n)___in vapor pressure.increase, increaseDescribe the relationship between intermolecular forces and the vapor pressure of a substance.a substance with weaker intermolecular forces vaporizes more easily and has a high vapor pressure.The pressure exerted by the ___ above a liquid is called the equilibrium ___ pressure. This pressure ___ as the temperature of the system increases.vapor, vapor. increasesDescribe the relationship between the intermolecular forces of a molecular substance and its boiling point?1. A substance with strong intermolecular forces will require more energy to separate the molecules so that they can enter the vapor phase.
2. A substance with weak intermolecular forces will have a low boiling point.If the external pressure on a liquid is increased, the vapor pressure of the liquid must___ in order for the liquid to boil. The molecules of the liquid require___ kinetic energy so that more of them can escape the liquid phase. The boiling point of the liquid is therefore ___ when the external pressure is increased.increase, more, higherDescribe the boiling point of a substance1. The boiling point is the temperature at which the vapor pressure equals the external pressure.
2. The boiling point of a substance increases as the external pressure increases.
3. Boiling occurs when the vapor pressure of the liquid is sufficient for bubbles of vapor to form in the interior of the liquid.Describe melting and melting point1. At melting point of a substance the solid and liquid phases are in equilibrium.
2. Pressure changes have little effect on the melting point of a substance.Describe bonding and intermolecular forces1. Bonding forces are generally much stronger than intermolecular forces.
2. For a molecular substance, the strength of the intermolecular forces determines the physical properties of its phases.
2. Intermolecular forces involve partial or small charges that are far apart and are relatively weak.When two polar molecules are close to each other they will orient themselves so that the positive pole of one molecule attracts the ___ pole on the adjacent molecule. These intermolecular forces are called ___ - ___ forces.negative, dipole-dipolewhich structures would allow a molecular substance to exhibit hydrogen bonding between molecules?1. One or more O-H bonds
2. One or more N-H bondsTrue or False: A bond between O and H within any molecule is called a hydrogen bondFalseWhat is needed to calculate the numerical change in vapor pressure with change in temperature1. R= 8.314 J/K*mol
2. One or both of the vapor pressures
3. Delta H(vap)The boiling point of a substance is the temperature at which the vapor pressure of the substance is ___ the external pressure; hence the boiling point depends on the applied pressure.equal toThe melting point of a substance is the temperature at which the particles have enough ___ energy to break free from the ___ phase and enter the ___ phase.kinetic, solid, liquidBonding forces include ionic bonds, metallic bonds, and ___ bonds. These types of forces are much ___ than the forces of attraction between individual molecules, which are called ___ forces.covalent, stronger, intermolecularTrue or False: A compound containing one or more oxygen atoms is not necessarily capable of forming hydrogen bonds between its molecules.trueWhen hydrogen is covalently bonded to ___, oxygen, or fluorine there will be an attraction between such a hydrogen and a(n) ___ pair of electrons on a nitrogen, oxygen, or fluorine atom on an adjacent molecule. This attraction is called a(n) ___ bond and it is strongest type of intermolecular force between neutral species.nitrogen, lone, hydrogenDescribe polarizabilityThis is a measure of how the electron cloud around an atom responds to its electronic environment.Describe the general trends in polarizabilty1. Polarizability increases down a group on the periodic table
2. Anions are larger than their parent atoms and are therefore more polarizable
3. The greater the number of electrons a particle has, the greater its polarizability will generally be.True or False: Dispersion forces are exhibited only by nonpolar molecules.falseA momentary change in the electron density surrounding an atom or a molecule causes it to have a(n)___ dipole even if it is not normally polar. This induces a similar effect in a nearby molecule or atom and there will be a weak attraction between the two particles as a result. These weak interactions are called ___ forces or London forces.instantaneous, dispersionWhat is the relationship between dispersion forces and particle size?1. Large particles are more polarizable and experience stronger dispersion forces.
2. For molecules of similar shape, dispersion forces tend to increase with increasing molar massHow does polarizability affect intermolecular forces?A more polarized molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overallWhat is the relationship between molecular shape and the strength of dispersion forces?molecules with a large surface area have more points of contact and therefore experience stronger dispersion forces.Describe the surface tension of a liquid1. A polar liquid will have higher surface tension than a nonpolar liquid
2. Surface tension is the result of a net downward and inward force on the surface particles of a liquid
3. Surface tension is the amount of energy required to increase the surface area of a liquid by a unit areaThe surface tension of a liquid will be ___ for a liquid with stronger forces of attraction between its particles.greaterA liquid rises against the pull of gravity through a narrow space through capillary action. This results from a competition between ___ intermolecular forces between the molecules of the liquid itself and the ___ forces between the liquid and the walls of the container.cohesive; adhesiveSince H2O is able to exhibit different types of intermolecular forces including hydrogen bonding, this substance has a ___ heat capacity and a ___ heat of vaporization compared to other liquids.high; highThe number of nearest neighbors for a particle in the unit cell of a crystal is called the ___ number of particlescoordinationThe hexagonal close-packed structure has the patternabababThe cubic-packed structure has the patternabcabcIn hexagonal closest packingthe particles of the third layer lie directly over the particles of the first layerIn cubic closest packingThe particles of the third layer do not lie directly over the particles of the first layerDiamond is one of the common crystalline forms of ___ in which each atom is bonded to 4 others by strong, ___ bonds to create a large 3-D array.carbon, silicon covalentHow does the addition of phosphorus to silicon create an n-type semiconductor?The extra electrons from the phosphorus atoms bridge the gap between the valence and conductance bands, increasing conductivity.Compounds that maintain an orderly arrangement of particles in the liquid phase are known as liquid __crystalsWhat are typical properties of ceramics?strength, thermal insulation, hardnessThe electrons of a smaller atom or ion are___ the nucleus and held ___ tightly than those of a larger atom or ion. A smaller atom or ion is therefore___ polarized than a larger one.closer to, more, lessDispersion forces are the only type on intermolecular force exhibited by atoms and by ___ molecules. Without the existence of dispersion forces, such substances could not exist in the ___ states of matter.nonpolar, condensedThe larger a molecule or atom, the ___ the number of electrons and the ___ polarized it will generally be. The strength of the dispersion forces for a particular substance therefore generally ___ as molar mass increases, providing molecules of similar shape are compared.greater, more, increasesAll particles experience ___ forces, a weak attraction that results from induced electron cloud distortion. These forces increase the overall attraction between particles. The more polarized a particle, the ___ this effect will be.dispersion, greatermolecules with a large surface are have ___ points of contact between them than molecules with less surface area. This leads to ___ dispersion forces overall.more, strongerCH3OHhydrogen bondingCH3Fdipole-dipole forcesC3H8dispersion forcesCaCl2ionic bondingH2O exhibits extremely strong and efficient hydrogen bonding between its molecules. What is the result of this behavior?1. High capillarity
2. High specific heat capacity
3. High surface tensionThe particles in a crystal are arranged in an orderly 3-D array called the crystal ___. The simplest repeating unit of the crystal is called the unit___.lattice, cellDescribe the different packing arrangements observed for cubic unit cells?1. In hexagonal closest packing, the particles of the third layer lie directly over the particles of the first layer.
2. The cubic close-packed structure has the repeating pattern abcabc
3. Cubic closest packing is based on the face-centered cubic cellDescribe the bonding in graphite1. The pi bonds in graphite are delocalized, allowing graphite to conduct electricity.
2. Graphite consists of flat sheets or layers of carbon atoms that are covalently bonded together with the sheet.A p-type semiconductor is formed by doping silicon with any Group 3A element. This ___the number of valence electrons available, creating___sites into which Si electrons can migrate. This increases the conductivity of the material.decreases, positiveAll___ are nonmetallic inorganic compounds.ceramicsThe phase changes of many substances are reversible and a phase change, just like a chemical reaction, may reach ___providing it takes place in a(n)___system.equilibrium, closedAtomic solidindividual atoms held together by dispersion forcesIonic solidcations and anions arranged in a regular lattice held together by ion-ion attractionMolecular solidindividual molecules held together by various combinations of intermolecular forcesNetwork covalent solidatoms held together by covalent bondsSimple cubicThe centers of eight identical particles define the corners of a cubeBody-centered cubicIdentical particles lie at each corner and in the center of the cubeFace-centered cubicIdentical particles lie at each corner and in the center of each face but not in the center of the cubeThe attraction between an ion and a nearby polar molecule is called an ion-___interaction. This attraction force is important when a(n)___ compound dissolves in a polar solvent such as H2Odipole, ionicThe liquid and ___ states are called the ___states of matter because their particles are very close together.solid, condensedUnlike most other substances, the density of solid H2O is___ than the density of the liquid; hence water ___ when it freezes. This is reflected in the phase diagram for H2O. The solid-liquid boundary line has a negative slope, reflecting the fact that the higher the pressure the ___ the temperature at which the water freezes.less, expands, lowerMolecularfairly soft with low melting points, poor conduction of heat and electricityIonichard and brittle with high melting points, good thermal and electrical conductivity in the molten phase.MetallicSoft to hard, varying melting points, excellent conductors of electricity ad heat as well as malleable and ductileNetwork Covalentvery hard with high melting points but usually poor thermal and electrical conductors.What does the term doping refer to in semiconductors?The addition of a small amount of a Group 3A or Group 5A element to a semiconductor sampleDescribe the three types of cubic unit cells1. Each particle in a simple cubic unit cell has a coordination number of 6
2. The face-centered cubic cell has no particles in the center of the cube
3. The body-centered cubic unit cell has 2 atoms per unit cellDescribe van der Waals radi1. The van der waals radius for a given atom is larger than its covalent radius
2. The van der Waals distance and radius are important for determining how closely and two molecules can approach each other.
3. In general, van der waals radii increase down a group in the periodic tableDescribe sublimation1. nonpolar molecular substances are more likely to sublime than polar substances.
2. The tendency of a molecular substance to sublime is related to the strength of its intermolecular forces.
3. Sublimation is the change from the solid directly to the gas phaseConductorThere is no energy gap between the valence and conduction bands so electrons flow freelySemiconductorThe energy gap between the valence and conduction bands is small so electrons can cross if thermally excited.InsulatorThe energy gap between the valence and conduction bands is large and no current can flowDescribe packing efficiency of a unit cellThe percentage of the total volume occupied by the particles themselvesLiquid crystalconsist of a crystal phase that flows like a liquid but has an ordered shapeCeramic crystalConsists of mostly covalent solids formed at high temperature that are very resistant to heat and chemicalsPolymeric crystalConsists of extremely large molecules that adopt the shape of coils due to intermolecular forces.Nano-structural crystalConsist of materials that do not behave as atoms or as crystals; sizes range from 1 to 100 nmSolids that have well defined shapes due to the orderly arrangement of their particles are called ___ solids, whereas solids whose particles lack orderly placement and therefore have poorly defined shapes are ___ solidscrystalline, amorphousThe ___pattern of H bonding in H2O gives ice a very open structure with large ___ between the molecules. Water therefore differs from most liquids because it becomes ___ dense when it freezes.tetrahedral, spaces, lessThe triple point is represented on a phase diagram to show when all three ___of a substance are at ___phases, equilibriump-typedoped with a group 3A elementn-typedoped with a group 5A elementWhat is a modern application of a liquid crystal?1. Calculator and watch displays
2. High -strength materials
3. Color changing thermometersDescribe the critical temperature and pressure of a substance1. At the critical point of a substance, the densities of the liquid and gas are equal
2. At temperature and pressures above the critical point a substance exists as a supercritical fluidAdhesive forcesattractive forces between the liquid and the particles of the containerCohesive forcesintermolecular forces within the liquid itselfDescribe viscosity of a liquid1. Viscosity is a liquids resistance to flow
2. A liquid with stronger intermolecuar forces will have a higher viscosity
3. The viscosity of a given liquid decreases with increasing temperatureElectrical conductivitythe highest energy electrons are excited into empty orbitals allowing them to move readily through a sampleLusterelectrons absorb and release photons as they move between the valence and conduction bandsMalleabilitypositive metal ions can move past each other protected by the repulsion of the delocalized electronsThermal conductivitythe highest energy electrons are excited by heat and the energy is transferred as kinetic energyEnergy of motion is high compared to the attraction between particles; particles are far apart.gasThe forces of attraction between particles are appreciable; fixed volume; freedom of movement allows fluidity.liquidEnergy of movement is low compared to the attraction between particles; particles remain fixed in position relative to each other.solidA physical state of matter that is chemically and physically uniform is called a(n) ______.phaseAt ______ temperatures the forces of attraction between particles dominate because the particles are moving slowly. At ______ temperatures the movement of the particles overcomes the attractions.lower, higherWhich of the following options correctly describe the boiling point of a substance? Select all that apply.-The boiling point of a substance increases as the external pressure increases.
-The boiling point is the temperature at which the vapor pressure equals the external pressure.
-Boiling occurs when the vapor pressure of the liquid is sufficient for bubbles of vapor to form in the interior of the liquid.
(Notes:
-A liquid can evaporate at any temperature. There will always be some molecules in the liquid with enough energy to escape into the vapor phase. The boiling point is specifically defined as the temperature at which the vapor pressure of the liquid equals the external pressure.
-If the external pressure increases the substance will have to be heated to a higher temperature so that its vapor pressure can increase to equal the external pressure.)In a molecular substance, the covalent bonds between the atoms hold the individual molecule together as a unit and are referred to as ______ forces. The nonbinding forces of attraction between one individual molecular and another are called ______ forces. The physical behavior of the phases of matter reflect the difference in the strength of their ______.intramolecular, intermolecular, intermolecular forcesThe pressure exerted by the ______ above a liquid at equilibrium is called the equilibrium ______ pressure. This pressure ______ as the temperature of the system increases.vapor, vapor, increasesΔH(vap)liquid→gas-ΔH(fus)liquid→solidΔH(subl)solid→gasΔH(fus)solid→liquidWhich statement correctly describes the relationship between intermolecular forces and the vapor pressure of a substance?A substance with weaker intermolecular forces vaporizes more easily and has a high vapor pressure.q=nCΔTheating or cooling within a phase if moles are givenq=nΔH°(change)heating or cooling during a phase changeq=mcΔTheating or cooling within a phase if mass is givenThe vapor pressure of a given molecular substance is affected by changes in _______ and by the strength of the _______ forces for the substance.temperature, intermolecularA heating-cooling curve shows the changes that occur when ______ is added to or removed from a sample of matter at a ______ rate.heat, constantCondensation, freezing, and deposition are ______ phase changes, whereas melting, vaporization, and sublimation are ______ changes.exothermic, endothermicWhich of the following options correctly describe a phase equilibrium? Select all that apply.-At equilibrium, the amount of the substance in each phase remains constant.
-If the rate of condensation is equal to the rate of evaporation, a phase equilibrium exists.
-A system must be closed in order for a phase equilibrium to be established.Which of the following statements correctly describes the relationship between the boiling point of a substance and the external pressure?At a lower external pressure, the molecules of the substance require less energy to form bubbles of vapor and the boiling point is lower.If a liquid is placed in a closed container, molecules with sufficient ______ will move from the liquid to the gas phase. Gas phase molecules will in turn condense. Eventually the ______ of evaporation and condensation will be equal and the system is said to have reached phase ______.kinetic energy, rates, equilibriumWhich of the following statements correctly describe the relationship between the intermolecular forces of a molecular substance and its boiling point? Select all that apply.-A substance with weak intermolecular forces will have a low boiling point.
-A substance with strong intermolecular forces will require more energy to separate the molecules so that they can enter the vapor phase.Heat is added or removed but temperature remains the same.during a phase changeHeat change causes a temperature change.within a phasedraws particles together due to forces of attraction; dominates in the solid phasepotential energytends to disperse the particles of a substance; dominates in the gas phasekinetic energyThe melting point of a substance is the temperature at which the particles have enough ______ energy to break free from the ______ phase and enter the ______ phase.kinetic, solid, liquid
(Note: Substances require enough kinetic energy to break the strong intermolecular forces in the solid phase and escape into the liquid phase.)An increase in the temperature of a substance will ______ the fraction of molecules that have enough kinetic energy to escape the liquid phase and will therefore cause a(n) ______ in the vapor pressure.increase, increase
(note: An increase in temperature causes an increase in vapor pressure.)Which of the following statements correctly describe melting and melting point? Select all that apply.-At the melting point of a substance the solid and liquid phases are in equilibrium
-Pressure changes have little effect on the melting point of a substance.
(Notes:
-During melting there is no change in temperature, therefore no change in the average kinetic energy of the particles. It is the potential energy that increases during the melting process.
-Since the particles of liquids and solids are close together melting point is only slightly affected by pressure changes.)If a system at equilibrium is disturbed, the system will respond in such a way as to ______ the effect of the disturbance. If a liquid-vapor equilibrium is disturbed by removing some of the vapor, the pressure in the system will ______. The system will respond by increasing the rate of ______ until equilibrium is re-established and the vapor pressure is equal its original value.cancel, decrease, evaporationAn increase in temperature will cause the vapor pressure of a substance to ______.increaseThe triple point is represented on a phase diagram to show when all three ______ of a substance are at ______.phases, equilibriumThe phase changes of many substances are reversible and a phase change, just like a chemical reaction, may reach ______ providing it takes place in a(n) ______ system.equilibrium, closedIf a molecular substance has strong intermolecular forces the molecules at the surface of the liquid are held ______ tightly and vaporize ______ easily than the molecules with weaker intermolecular forces. The amount of substance in the vapor phase will be ______ than for molecules with weak intermolecular forces and the vapor pressure will therefore be ______.more, less, less, lowerWhich of the following statements correctly describe sublimation? Select all that apply.-The tendency of a molecular substance to sublime is related to the strength of its intermolecular forces.
-Sublimation is the change from the solid directly to the gas phase.
-Nonpolar molecular substances are more likely to sublime than polar substances.
(Note: A nonpolar molecular substance will tend to have weaker intermolecular forces than a polar substance. A nonpolar substance will therefore sublime more easily than a polar substance of similar molecular mass.)A phase diagram is a plot of ______ on the x-axis vs. ______ on the y-axis. This diagram shows the stable regions for each ______ of matter and the conditions under which these may exist in equilibrium.temperature, pressure, phaseWhich of the following statements correctly describe the critical temperature and pressure of a substance? Select all that apply.-At the critical point of a substance, the densities of the liquid and gas phases are equal.
-At the temperatures and pressures above the critical point a substance exists as a supercritical fluid.Unlike most other substances, the density of solid H2O is ______ than the density of liquid; hence water ______ when it freezes. This is reflected in the phase diagram for H2O (shown). The solid-liquid boundary line has a negative slope, reflecting the fact that the higher the pressure the ______ the temperature at which the water freezes.less, expands, lowerRank the states of matter based on increasing strength of intermolecular forces, placing the state whose intermolecular forces are weakest at the top.Gas. Liquid, SolidWhich of the following are known as condensed phases? Select all that apply.Liquids
SolidsMatch each phase change correctly to the term used to describe the process.Gas → Liquid: Condensation
Liquid → Solid: Freezing
Solid → Gas: Sublimation
Liquid → Gas: Vaporization Evaporation
Solid → Liquid: MeltingSelect all the statements that correctly describe the molar heat of vaporization for a substance.ΔHvap is the amount of heat required to vaporize 1 mole of a substance at its boiling point.
ΔHvap is a positive quantity.
Both the boiling point and ΔHvap of a molecular substance are related to the strength of the intermolecular forces.Select all the statements that correctly describe the critical temperature and pressure of a substance.A supercritical fluid is the state of a substance when its temperature and pressure both exceed Tc and Pc respectively.
A gas cannot be liquefied at temperatures above its Tc.Which of the following factors influence whether a given substance exists as a gas, liquid, or solid? Select all that apply.Intermolecular forces
TemperatureSolids and liquids have intermolecular forces large enough to keep the particles in contact and are referred to as the ____ phases.Blank 1: condensedCondensation and freezing are ______ phase changes, whereas melting, vaporization, and sublimation are ______ changes.exothermic, endothermicThe amount of heat required to vaporize 1 mole of substance at its boiling point is referred to as the molar ____ of ____ ΔHvap.Blank 1: heat or enthalpy
Blank 2: vaporizationThe temperature above which a gas cannot be liquefied by increasing the pressure on it is called its ___temperature. A fluid at a temperature and pressure above Tc and Pc is called a ___ fluid.Blank 1: critical
Blank 2: supercriticalWhich of the following correctly describes a heating-cooling curve?A plot of heat vs. temperature for a substance that is heated or cooled at a constant rate and constant pressureMatch the effect of heating/cooling a substance to the change in temperature that occurs in each case.
InstructionsWithin a phase: Heat change causes a temperature change.
During a phase change: Heat is added or removed but temperature remains the same.Match each lettered portion of the following heating curve to the correct description.
Instructionsp: The substance is in the solid phase.
s: The substance is changing from liquid to vapor.
q: Both solid and liquid phases are present.
r: The kinetic energy of the liquid particles is increasing.
t: The particles are far apart and movement dominates the phase.A heating curve shows the changes in ___ that occur when ___ is added to or removed from a sample of matter.Blank 1: temperature
Blank 2: heatWhich statement correctly describes the process of melting and the melting point of a substance?At the melting point of a substance, the solid and liquid phases are in equilibrium.Within a phase, a change in heat causes the temperature of the substance to _____ as the _____ energy of the molecules changes. During a phase change, however, a change in heat causes a change in the _____ energy of the molecules and the temperature will _____.change; kinetic; potential; stay the sameWhich statement correctly explains why ΔHofus is typically much smaller than ΔHovap for a given substance?More energy is required to fully separate particles than to move particles out of their fixed positions in the solid.In which region of the heating curve shown are both the liquid and the gas phases of the substance present?Between C and DThe process by which a substance transitions directly from the solid phase to the vapor phase is known as ___. The reverse process, in which gas molecules go directly to the solid phase, is known as ____.Blank 1: sublimation
Blank 2: depositionA 25.0-g sample of ice at -6.5oC is removed from the freezer and allowed to warm until it melts. Given the data below, select all the options that correctly reflect the calculations needed to determine the total heat change for this process.
Melting point at 1 atm = 0.0oC; ssolid = 2.09 J/goC; sliquid = 4.21 J/goC; ΔHofus = 6.02 kJ/molThe total heat change for the process is equal to +8.71 kJ.
q for the phase change is given by 1.39 x 6.02 = 8.37 kJ.The molar heat of ____ is the amount of energy required to melt 1 mole of solid. The energy change that occurs when 1 mole of liquid freezes is ____ n magnitude but ____ in sign.Blank 1: fusion
Blank 2: equal, equivalent, or the same
Blank 3: oppositeIn general, ΔHofus is _____ than ΔHovap for a given substance because it takes _____ energy to overcome the forces holding the molecules in fixed positions (i.e., melt the substance) than to separate the molecules completely from each other (i.e., vaporize the substance).lower; lessA sample containing 2.50 g liquid diethyl ether is cooled from 25.5oC to 3.5oC. The substance remains in the liquid phase throughout this change. Select all the options that correctly reflect the calculations needed to determine q for this process.
(s for liquid diethyl ether = 172 J/mol.K and its molar mass is 74.12 g/mol.)q = -0.13 kJ
The sample contains 3.37 x 10-2 mol of diethyl ether.True or false: The molar enthalpy of sublimation of a given substance can be determined if its enthalpies of fusion and vaporization are known.TA sample of ethanol containing 0.35 mol is cooled from 125.0cC to 62.0oC. Given the data below, select all the options that correctly reflect how to calculate the total heat change for the process.
Boiling point for ethanol at 1 atm = 78.5oC; ΔHovap = 40.5 kJ/mol; Cliq = 1130 J/mol⋅oC; and sgas = 65.9 J/mol⋅oCThis process involves 3 separate stages.
q for the phase change = 0.35 x -40.5 = -14 kJGiven the following information, what is the enthalpy change when 54.5 g of water vapor is heated from 100.0°C to 200.0°C? (sgas= 33.1 J/mol.K and ΔH°vap = 40.7 kJ/mol)1.00 × 10^4 JWhich equation should be used to calculate the heat change when a given mass of H2O is heated from 15oC to 95oC?q = msΔTThere are two equations used to calculate the heat gained/lost by a substance. Match each equation to its correct application.
Instructionsheating or cooling during a phase change: q = nΔHochange
heating or cooling within a phase if mass is given: q = msΔT
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