Chemistry Chapter 12, Chapter 12, Chem 102 Connect 12.5-12.6, Chapter 12 SmartBook, Chem 2 Chapter 12, Chemistry 124 Chapter 12: Molecular Nature of Matter (Jursich), Phase Change Reading
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*100
Calculate 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 endothermic
Which 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.
Which 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 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.
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.)
Which 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.)
Which 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 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.)
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 -intermolecular
which 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 forces
Which 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 bonds
Describe the surface tension of a liquid
1. 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 area
Describe 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.
Describe melting and melting point
1. 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 the critical temperature and pressure of a substance
1. 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 fluid
Describe bonding and intermolecular forces
1. 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.
What is a modern application of a liquid crystal?
1. Calculator and watch displays 2. High -strength materials 3. Color changing thermometers
Describe the three types of cubic unit cells
1. 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 cell
H2O 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 tension
H2O 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 tension
Describe equilibrium
1. 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.
Describe 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 cell
What 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 mass
which 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 bonds
Describe the general trends in polarizabilty
1. 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.
What is needed to calculate the numerical change in vapor pressure with change in temperature
1. R= 8.314 J/K*mol 2. One or both of the vapor pressures 3. Delta H(vap)
Describe the boiling point of a substance
1. 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 the bonding in graphite
1. 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.
Describe van der Waals radi
1. 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 table
Describe vapor pressure
1. 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.
Describe viscosity of a liquid
1. 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 temperature
Describe sublimation
1. 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 phase
Given 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 J
Given the following information, what is the enthalphy change when 54.5 g of water vapor is heated from 100*C to 200*C
54.5g*(1mol/18.02g) = 100X10^4J q = 3.02 X 33.1 * 100
Which 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 statement correctly explains how polarizability affects intermolecular forces?
A more polarizable molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overall.
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.
How does polarizability affect intermolecular forces?
A more polarized molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overall
Which of the following correctly defines a phase of matter?
A physical state that is physically distinct and homogeneous
Which 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
Which 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
Which 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.
Describe 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.
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.
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.
Which 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.
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.
Describe phase equilibrium. 3 statements
A system must be closed in order for a phase equilibrium to be established. At equilibrium, the amount of substance in each phase remains constant. If the rate of condensation is equal to the rate of vaporization, a phase equilibrium exists
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 random
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.
Which 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.
Which 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 fluid
Which 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 equilibrium
Which 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.
In which region of the heating curve shown are both the liquid and the gas phases of the substance present?
Between C and D
Solids and liquids have intermolecular forces large enough to keep the particles in contact and are referred to as the ____ phases.
Blank 1: condensed
The 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: supercritical
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: opposite
The 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: vaporization
The 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: deposition
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: heat
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.
select all statements that describe molar heat of vaporization
Both 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 quantity
What principal intermolecular force keeps these molecules together? CH3OH CH3F C3H8 CaCl2
CH3OH-hydrogen bonding CH3F-dipole dipole C3H8-dispersion CaCl2-ionic bonding
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 same
A 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; Adhesive
Gas to Liquid
Condensation
Match each phase change correctly to the term used to describe the process. Gas → Liquid Liquid → Solid Solid → Gas Liquid → Gas Solid → Liquid Gas → Solid
Condensation Freezing Sublimation Vaporization Melting/Fusion Deposition
Nano-structural crystal
Consist of materials that do not behave as atoms or as crystals; sizes range from 1 to 100 nm
Polymeric crystal
Consists of extremely large molecules that adopt the shape of coils due to intermolecular forces.
Ceramic crystal
Consists of mostly covalent solids formed at high temperature that are very resistant to heat and chemicals
The 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 ____ fluid
Critical; Supercritical
Surface tensiob
Debris and bugs readily float on the surface of water because it has the highest ______ of any liquid except for some molten metals and salts.
Gas to Solid
Deposition
Which intermolecular forces are exhibited between molecules of the compound shown?
Dipole-dipole forces Dispersion forces
Which 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 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.
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.
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 , Closed
True or False: A bond between O and H within any molecule is called a hydrogen bond
False
True or false: Dispersion forces are exhibited only by nonpolar molecules.
False
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.
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 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 forces
Liquid to Solid
Freezing
The 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 sign
Fusion; Equal; Opposite
Match 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: Melting
Rank the states of matter based on increasing strength of intermolecular forces, placing the state whose intermolecular forces are weakest at the top.
Gas. Liquid, Solid
Which 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 electricity
Water 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 seperation
A substance with weaker intermolecular forces vaporizes more easily and....
Has a high vapor pressure
A heating cooling curve shows the changes that occurs when ____ is added to or removed from a sample of matter at a _____ rate
Heat, constant,
H2O 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 capillarity
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; High
Face-centered cubic
Identical particles lie at each corner and in the center of each face but not in the center of the cube
Body-centered cubic
Identical particles lie at each corner and in the center of the cube
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 pressure
Increase, increase
The physical state of a molecular substance at a particular temperature and pressure depends on the strength of its
Intermolecular forces
The 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 Temperature
Which of the following factors influence whether a given substance exists as a gas, liquid, or solid? Select all that apply.
Intermolecular forces Temperature
Covalent bonds are classified as
Intramolecular 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.
Ion-dipole forces
For a pure substance, delta H for each phase change is given in units of ____ per ____ of substance. Delta H is measured at a pressure of ____ atm and the temperature of the change
Kilojoules, mole, 1
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.
Delta H(vap)
Liquid to Gas
- Delta H(fus)
Liquid to Solid
Which of the following are known as condensed phases? Select all that apply.
Liquids Solids
Unlike 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 freezes
Lower; Expands; Lower
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;Higher
Solid to Liquid
Melting/Fusion
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 forces.
Which 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.
Molecules 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; Stronger
A 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.
Dispersion 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 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 bonds
A physical state of matter that is chemically and physically uniform is called a(n) _____. Multiple choice question.
Phase
The triple point is represented on a phase diagram to show when all 3 ____ of a substance are at ____
Phases; Equilibrium
The heat lost in the cooling process (q) is the _____
Product of the amount (n) of substance, the molar heat capacity of substance in certain phase, and the temperature change during this step Final T - Initial T; (moles)(c of specific phase)( Tf-Ti)
Viscosity
Resistance of fluid to flow
Metallic
Soft to hard, varying melting points, excellent conductors of electricity ad heat as well as malleable and ductile
Delta H(subl)
Solid to Gas
Delta H(fus)
Solid to Liquid
Water has a very high specific heat capacity compared to other common liquids. This property is due to ______ water.
Strong hydrogen bonding in
Intermolecular 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 phase
Stronger; Greater
Solid to Gas
Sublimation
If 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 unstable
Supercooled
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 area
True or false: The molar enthalpy of sublimation of a given substance can be determined if its enthalpies of fusion and vaporization are known.
T
A heating curve shows the changes in ____ that occur when ____ is added or removed from a sample of water
Temperature; Heat
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; Phase
As 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.
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 sample
Simple cubic
The centers of eight identical particles define the corners of a cube
Insulator
The energy gap between the valence and conduction bands is large and no current can flow
Semiconductor
The energy gap between the valence and conduction bands is small so electrons can cross if thermally excited.
How 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.
Intermolecular forces
The forces of attraction between one individual molecule and another.
Which 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.
Which 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.
Which 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.
In cubic closest packing
The particles of the third layer do not lie directly over the particles of the first layer
Describe packing efficiency of a unit cell
The percentage of the total volume occupied by the particles themselves
Select the correct description of capillary action.
The rising of a liquid through a narrow space against gravity
A 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 q
The sample contains 3.337X10^-2 mol diethyl ether q=-0.13 kJ
Match each lettered portion of the following heating curve to the correct description. p s q r t
The 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.
What will affect the vapor pressure of a pure molecular substance?
The temperature, the strength of the intermolecular forces, and the structure of the substance
A 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/mol
The 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.
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.
Conductor
There is no energy gap between the valence and conduction bands so electrons flow freely
Which 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.
Describe polarizability
This is a measure of how the electron cloud around an atom responds to its electronic environment.
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.
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.
A 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⋅oC
This process involves 3 separate stages. q for the phase change = 0.35 x -40.5 = -14 kJ
The molar enthalpy of sublimation of a given substance can be determined if its enthalpies of fusion and vaporization are known
True
True 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 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, increases.
Liquid to Gas
Vaporization
Answer 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.
Match the effect of heating/cooling a substance to the change in temperature that occurs in each case. Instructions
Within a phase: Heat change causes a temperature change. During a phase change: Heat is added or removed but temperature remains the same.
Match the effect of heating/cooling a substance to the change in temp that occurs
Within a phase: heat change causes a temperature change During a phase change: Heat is added or removed but temperature remains the same
ion-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.
A solution is
a homogeneous mixture meaning it exists in a single phase
Describe 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 hexagonal close-packed structure has the pattern
ababab
The cubic-packed structure has the pattern
abcabc
Which of the following statements correctly describe dispersion or London forces?
all covalent compounds exhibit dispersion forces dispersion forces are a weak attraction between temporary dipoles
Network covalent solid
atoms held together by covalent bonds
Adhesive forces
attractive forces between the liquid and the particles of the container
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 dipoles
c) all covalent compounds exhibit dispersion forces d) dispersion forces are a weak attraction between temporary dipoles
What is miscible
can dissolve in any proportion
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, evaporation
Diamond 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 covalent
Ionic solid
cations and anions arranged in a regular lattice held together by ion-ion attraction
All___ are nonmetallic inorganic compounds.
ceramics
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 same
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 same
The 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, less
A 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; adhesive
Liquid crystal
consist of a crystal phase that flows like a liquid but has an ordered shape
The number of nearest neighbors for a particle in the unit cell of a crystal is called the ___ number of particles
coordination
A change in the physical state of a molecular substance does NOT involve the breaking of
covalent bonds
Half 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 radius
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, intermolecular
Solids 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 ___ solids
crystalline, amorphous
Compounds that maintain an orderly arrangement of particles in the liquid phase are known as liquid __
crystals
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, positive
Polarity
describes 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.
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, ionic
The 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 H2O
dipole, ionic
CH3F
dipole-dipole forces
C3H8
dispersion forces
All 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, greater
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, stronger
p-type
doped with a group 3A element
n-type
doped with a group 5A element
Heat is added or removed but temperature remains the same.
during a phase change
Fluorine, 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; small
Luster
electrons absorb and release photons as they move between the valence and conduction bands
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, equilibrium
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
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
The boiling point of a substance is the temperature at which the vapor pressure of the substance is ___________ the external pressure
equal to
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, closed
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, closed
Condensation and freezing are ______ phase changes, whereas melting, vaporization, and sublimation are ______ changes.
exothermic, endothermic
Condensation, freezing, and deposition are ______ phase changes, whereas melting, vaporization, and sublimation are ______ changes.
exothermic, endothermic
Condensation, freezing, and deposition are _____ phase changes, whereas melting, vaporization, and sublimation are _____ changes. Multiple choice question.
exothermic; endothermic
Condensation, 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.
Molecular
fairly soft with low melting points, poor conduction of heat and electricity
True or False: Dispersion forces are exhibited only by nonpolar molecules.
false
Energy of motion is high compared to the attraction between particles; particles are far apart.
gas
The surface tension of a liquid will be ___ for a liquid with stronger forces of attraction between its particles.
greater
The 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, increases
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 compared
greater; more; increases
Ionic
hard and brittle with high melting points, good thermal and electrical conductivity in the molten phase.
A heating-cooling curve shows the changes that occur when ______ is added to or removed from a sample of matter at a ______ rate.
heat, constant
q=nΔH°(change)
heating or cooling during a phase change
There are two equations used to calculate the heat gained/lost by a substance. Match each equation to its correct application. Instructions
heating or cooling during a phase change: q = nΔHochange heating or cooling within a phase if mass is given: q = msΔT
q=mcΔT
heating or cooling within a phase if mass is given
q=nCΔT
heating or cooling within a phase if moles are given
Colloid
heterogeneous two or more phases
The 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 vaporization
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, high
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; high
CH3OH
hydrogen bonding
"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.
An increase in temperature will cause the vapor pressure of a substance to _____.
increase
An increase in temperature will cause the vapor pressure of a substance to ______.
increase
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 vapor pressure.
increase, increase
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.)
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, higher
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, higher
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
Atomic solid
individual atoms held together by dispersion forces
Molecular solid
individual molecules held together by various combinations of intermolecular forces
A 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 dispersion
A 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, dispersion
Cohesive forces
intermolecular forces within the liquid itself
Match 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 of
intramolecular forces are the forces of attraction between one individual molecule and another intermolecular forces covalent bonds
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 forces
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 forces
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 _____. Multiple choice question.
intramolecular; intermolecular; intermolecular forces
What is the strongest type of dipole bond
ion dipole
CaCl2
ionic bonding
tends to disperse the particles of a substance; dominates in the gas phase
kinetic energy
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, equilibrium
As 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 dominate
kinetic, attraction, attractive
The 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
The 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.)
The 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, cell
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, lower
Unlike 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, lower
The forces of attraction between particles are appreciable; fixed volume; freedom of movement allows fluidity.
liquid
ΔH(vap)
liquid→gas
-ΔH(fus)
liquid→solid
At ___ 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, higher
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.
lower, higher
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.
lower; higher
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).
lower; less
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; less
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 forces
What 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.
If 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, lower
If 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, lower
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, stronger
molecules with a large surface are have ___ points of contact between them than molecules with less surface area. This leads to ___ dispersion forces overall.
more, stronger
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-dipole
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-dipole forces
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-dipole
When 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 hydrogen
When 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, hydrogen
Dispersion 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, condensed
Match each lettered portion of the following heating curve to the correct description. Instructions
p: 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 physical state of matter that is chemically and physically uniform is called a(n)
phase
A physical state of matter that is chemically and physically uniform is called a(n) ______.
phase
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.
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 equilibrium
The triple point is represented on a phase diagram to show when all three ______ of a substance are at ______.
phases, equilibrium
The triple point is represented on a phase diagram to show when all three ___of a substance are at ___
phases, equilibrium
The term _____ is used to describe how well the electron cloud around an atom responds to changes in its electronic environment.
polarizability
Malleability
positive metal ions can move past each other protected by the repulsion of the delocalized electrons
draws particles together due to forces of attraction; dominates in the solid phase
potential energy
For 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, kinetic
A 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.
This equation is used for the phase change from gas to liquid.
q = -nΔHovap
What is the equation for heating or cooling within a phase of mass is given
q = mcAT
Which equation should be used to calculate the heat change when a given mass of H2O is heated from 15oC to 95oC?
q = msΔT
Equation for heating or cooling during a phase change
q = nAH of change
Equation for heating or cooling within a phase of moles are given
q = nCAT
Which equation should be used to calculate the heat change when a given molar amount of H2O is heated from 15oC to 95oC?
q = nCΔT
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 given
q = nCΔT q = nΔHchange q = mcΔT
This equation is used for the phase change from liquid to gas.
q = nΔHovap
a 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/mol
q 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=8.37kJ
Which 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*deltaT
Solve 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*k
q=(45.1g/18.0153g/mol)*(-40.7kJ) = -102 kJ
Which equation should be used to calculate the heat change when a given molar amount of H2O is heated from 15C to 95C
q=n C deltaT
Energy of movement is low compared to the attraction between particles; particles remain fixed in position relative to each other.
solid
The liquid and ___ states are called the ___states of matter because their particles are very close together.
solid, condensed
ΔH(subl)
solid→gas
ΔH(fus)
solid→liquid
What are typical properties of ceramics?
strength, thermal insulation, hardness
The high capillary action of water is a result of its ______.
strong hydrogen bonding
Intermolecular 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 greater
The vapor pressure of a given molecular substance is affected by changes in ___ and by the strength of the ___ forces for the substance.
temperature, intermolecular
The vapor pressure of a given molecular substance is affected by changes in _______ and by the strength of the _______ forces for the substance.
temperature, intermolecular
The vapor pressure of a given molecular substance is affected by changes in ________ and by the strength of the _______ forces for the substance.
temperature, intermolecular
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, phase
The ___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, less
Thermal conductivity
the highest energy electrons are excited by heat and the energy is transferred as kinetic energy
Electrical conductivity
the highest energy electrons are excited into empty orbitals allowing them to move readily through a sample
In hexagonal closest packing
the particles of the third layer lie directly over the particles of the first layer
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 substance
The ______ represents the conditions of pressure and temperature where solid, liquid, and gas phases are stable.
triple point
True or False: A compound containing one or more oxygen atoms is not necessarily capable of forming hydrogen bonds between its molecules.
true
The 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 four
The 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, increases
The 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, increases
The pressure exerted by the ___ above a liquid is called the equilibrium ___ pressure. This pressure ___ as the temperature of the system increases.
vapor, vapor. increases
Network Covalent
very hard with high melting points but usually poor thermal and electrical conductors.
Heat change causes a temperature change.
within a phase
Select 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.
For 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 completely
