Schedule Chapter 11 Intermolecular Forces, Liquids and Solids Video One and Video Two notes are due on Day One of schedule… Date Topics and Demonstrations Assignment

Videocast Due

Zero 1,2, 9, 13, 14, 16, 18, 20 One One Intro Intermolecular Forces

Pre-lab and 1,2, 9, 13, 14, 16, 18, 20

Two

Two Lab: Evaporation and Intermolecular Attractions

Three 11.1-11.2/3 wax paper race, floating corks, jar with screen

22, 25 and quiz

Four 11.4 phase change ΔH

29, 34, 35, 39, 40 Three

Five 11.5 vapor pressure superheated steam, evaporation race

4, 5, 26, 45, 48, 50

Four

Six 11.6, phase diagrams and a tiny bit on crystals boil water with ice,

6, 53, 54, 71, 74, 75

Five

Seven Review

Practice Test

Eight Tests

Review for College Final Exam

Notes for Start of Unit (write them here):

More notes:

Electronegativity Review Dipole Moment How things “stick together”

a) LDF

b) D-D

c) H-Bonding

So, what “sticks together” the best: Sample Exercise 11.1 The dipole moments of acentonitrile, CH3CN, and methyl iodide, CH3I, are 3.9 D and 1.62 D, respectively. A. Which of these substances will have the greatest dipole-dipole attractions among its molecules? B. Which of these substances will have the greater London dispersion attractions? C. The boiling points of CH3CN and CH3I are 354.8 K and 315.6 K, respectively. What substance has the greater overall attractive forces? Sample Exercise 11.2 In which of the following substances is hydrogen bonding likely to play an important role in determining physical properties: methane (CH4), hydrazine (H2NNH2), methyl fluoride (CH3F), or hydrogen sulfide (H2S)? Sample Exercise 11.3 List the substances BaCl2, H2, CO, HF, and Ne in order of increasing boiling points.

Sample Exercise 11.4 Calculate the enthalpy upon converting 1.00 mol of ice at -25o to water vapor (steam) at 125o under a constant pressure of 1 atm. The specific of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, ∆Hfus = 6.01 J/g-K and ∆Hvap = 40.67 kJ/mol.

Sample Exercise 11.5 Use Figure 11.24 to estimate the boiling point of diethyl ether under an external pressure of .80 atm.

Sample Exercise 11.6 Referring to figure 11.28, describe any change in the phases present when H2O is A. Kept at 0o C while the pressure is increase from that at point 1 to that at point 5

B. Kept at 1.00 atm while the temperature increases from that at point 6 to that at point 9

Practice Test

Practice Test Chapter Eleven For the first three questions, use the key below. Select the description that best describes the substance. a) A network solid with covalent bonding b) A molecular solid c) An ionic solid d) A metallic solid e) An amorphous solid 1) Dry ice, solid carbon dioxide, CO2(s) 2) Diamond, solid C(s) 3) Brass, a mixture of copper and zinc 4) 1-propanol, CH3CH2CH2OH, boils at 97˚C and ethyl methyl ether,

CH3CH2OCH3, boils at 7˚C, although each compound has an identical chemical composition. The difference that is responsible for the higher boiling temperature is a) molar mass b) hydrogen bonding c) density d) specific heat e) enthalpy

5) Which of the following is true at the triple point of a pure substance? a) The temperature is equal to the normal melting point b) All three states have identical densities c) The solid-liquid equilibrium will always have a positive slope moving upward from the triple point d) The vapor pressure of the solid phase always equals the vapor pressure of the liquid phase e) The pressure is exactly one-half the critical pressure

6) The critical temperature of a substance is the a) temperature at which the vapor pressure of the liquid equals normal atmospheric pressure b) highest temperature at which a substance can exist in the liquid state, regardless of pressure c) temperature at which boiling occurs at 1.0 atm of pressure d) temperature and pressure where solid, liquid and vapor phases are all in equilibrium e) point at which pressure and temperature are less than zero.

7) Which describes volatile liquids? a) they have high vapor pressures b) they are stable only in the gas phase c) they are products of an exothermic reaction d) they burn with abundant evolution of energy e) they have negative values for heat of vaporization

8) What holds solid sodium together?

a) hydrogen bonding b) metallic bonding c) ionic bonding d) dipole forces e) London dispersion forces

9) What holds solid ICl together?

a) hydrogen bonding b) metallic bonding c) ionic bonding d) dipole forces e) London dispersion forces

10)

Liquid naphthalene at 95°C was cooled to 30°C, as represented in the cooling curve above. From which section of the curve can the melting point of naphthalene be determined?

a) A b) B c) C d) D e) E

11) Of the following pure substances, which has the highest melting point? a) S8 b) I2 c) SiO2 d) SO2 e) C6H6

12) Which explains why, at room temperature, I2 is a solid, Br2 is a liquid and Cl2 is a

gas? a) hydrogen bonding b) hybridization c) ionic bonding d) resonance e) London dispersion forces

13) In which of the following are the intermolecular forces listed from the weakest to the strongest? a) dipole-dipole > London > hydrogen bonds b) London < dipole-dipole < hydrogen bonds c) hydrogen bonds < dipole-dipole < London d) London > hydrogen bonds > dipole-dipole e) London < hydrogen bonds < dipole-dipole

14) Which consistently have the highest melting points? a) metals b) salts c) molecular crystals d) alkanes e) hydrogen bonded compounds

15) When at the same temperature, which compound is expected to evaporate most quickly? a) C8H18 b) C8H17OH c) C8H17NH2 d) C6H14 e) C7H15COOH

16) Which physical property can be determined if the unit cell and its dimensions are determined by X-ray diffraction?

a) heat capacity b) heat of fusion c) boiling and melting points d) vapor pressure e) density

17) The phase diagram below is used in questions 17 and 18.

Which describes the phase changes from point six to point nine?

a) evaporation, condensation b) melting, sublimation c) melting, boiling d) freezing, liquifaction e) melting, evaporation

18) Which describes the phase change from point five to point one? a) freezing, boiling b) freezing, deposition c) freezing, sublimation d) deposition, sublimation e) fusion, evaporation

19) On a phase diagram why does the line that separates the gas and liquid phases end rather than go to infinite pressure and temperature? a) Human technology has not devised equipment to raise pressures above 173

atmospheres b) The curve actually does go to infinity, but it is simply truncated for

convenience on a phase diagram c) No amount of pressure will liquefy a gas beyond this point d) The gas cannot undergo anymore significant temperature change e) A temperature increase will ionize the gas particles and the substance will

undergo a chemical change

20) The next two questions relate to the graph below. The graph shows the temperature of a pure substance as it is heated at a constant rate in an open vessel at 2.0 atm of pressure. The substance changes from the solid to the liquid to the gas phase.

The substance is above its normal freezing point at time.

a) t1 b) t2 c) t3 d) t4 e) t5

21) Which best describes what happens to the substance between t1 and t2?

a) The molecules are leaving the liquid phase b) The solid and liquid phases coexist in equilibrium c) The molecules moved from the solid to the liquid phase d) The average intermolecular distance is decreasing e) The molecules moved from the liquid to the vapor phase

22) The melting point of CaO is higher than that of KF. Explanations for this

observation include which of the following? I. Ca+2 is more positively charged than K+ II. O2- is more negatively charged than F-. III. The O2- ion is smaller than the F- ion.

a) II only b) I and II only c) I and III only d) II and III only e) I, II and III

23) A glass test tube partially filled with mercury liquid will form a convex surface,

whereas a glass test tube partially filled with water will form a concave meniscus. Which explains this best?

a) the cohesive forces of water are stronger than the adhesive forces of the glass

b) the cohesive forces of mercury are stronger than the adhesive forces of the glass

c) the adhesive forces of water are weaker than the adhesive forces of mercury

d) the surface tension of water is a very well studies phenomenon of water and no other substances has surface tension

e) the surface tension of mercury is much greater than water

24) Which is true about the vapor pressure of a liquid? a) it determines when a liquid will freeze b) it determines when a liquid will sublime c) it determines when a solid will change to a liquid d) it is a numerical measurement of the hydrogen bonds in a liquid e) it is the pressure exerted by the liquids vapor at equilibrium

25) Which substance will have the higher melting point? Explain why.

a) SiO2 b) CO2 c) CO d) CS4 e) SF4

26) List the following types of bonds in order of increasing strength:

Covalent bond in CH4 Ionic bond Dispersion force bond Dipole-Dipole bond Network covalent bonds in giant molecules like diamond C(s) Hydrogen bond

27) Explain why solid ethyl alcohol sinks in its own liquid; but solid water does not sink in liquid water.

28) What is a buckyball?

Practice Test II For questions 1-5 use the following choices: Hydrogen Bonding Metallic Bonding Ionic Bonding Dipole Forces London Dispersion Forces 1. What accounts for intermolecular forces in CCl4 molecules? 2. What explains why the boiling point of Acetic acid, CH3COOH, is greater than that of Acetone, CH3COCH3? 3. What holds solid sodium together? 4. What holds solid ICl together? 5. What holds Calcium Chloride together? 6. Which of the following liquids has the highest vapor pressure at 25ºC? A. CCl4 B. H2O2 C. H2O D. CH2Cl2 E. CHCl3 7. Which of the following is true of the critical temperature of a pure substance? A. It is the temperature above which the liquid phase can exist B. It is the temperature above which the liquid phase can not exist C. It is the temperature below which the liquid phase can not exist D. It is the temperature at which all three phases coexist E. It is the temperature at which the substance reaches, but can not go beyond, the critical pressure 8. DON’T DO…A metal crystallizes in a face-centered cube measuring 4.00 x 102 picometers on each edge. What is the radius of the atom? A. 141 pm B. 173 pm C. 200. pm D. 282 pm E. 565 pm 9. The molecules butane and 2-methylpropane are structural isomers. Which of the following would be the same for both, assuming constant temperature where necessary? A. Boiling Point B. Vapor Pressure C. Melting Point D. Solubility E. Gas Density 10. Which of the following lists intermolecular forces in order from strongest to weakest? A. dipole attractions, dispersion forces, hydrogen bonds B. hydrogen bonds, dispersion forces, dipole attractions C. dipole attractions, hydrogen bonds, dispersion forces D. hydrogen bonds, dipole attractions, dispersion forces

E. dispersion forces, hydrogen bonds, dipole attractions 11. Arrange in order of increasing boiling point: A. CH3CL, CO2, CH3OH, NaCl B. CO2, CH3Cl, CH3OH, NaCl C. CO2, CH3OH, CH3Cl, NaCl D. NaCl, CH3OH, CH3Cl, CO2 E. CH3OH, CO2, CH3Cl, NaCl 12. DON’T DO…A metal crystallizes in a cubic lattice. The unit cell edge length is 100. picometers. The density is 200. g/cm3. The atomic mass is 60.2 g/mol. How many of these atoms are there in a unit cell? A. 1.00 B. 2.00 C. 4.00 D. 6.00 E. 12.0 13. List the three states of matter in order of increasing molecular disorder. A. liquid < gas < solid B. gas < solid < liquid C. gas < liquid < solid D. solid < liquid < gas E. liquid < solid < gas 14. Which types of intermolecular attractive forces operate between polar molecules? A. dipole-dipole attraction B. London dispersion C. London-dispersion and hydrogen bonding D. hydrogen bonding E. London dispersion and dipole-dipole attraction 15. What types of intermolecular forces can exist between neutral molecules? A. London dispersion B. dipole-dipole attraction, London dispersion, and hydrogen bonding C. dipole-dipole attraction D. hydrogen bonding E. ionic interaction 16. What kind of attractive forces must be overcome to sublime CO2? A. dipole-dipole attraction B. hydrogen bonding C. London dispersion D. van der Waals forces E. all of these 17. Molecular nitrogen, N2, and carbon monoxide, CO, are isoelectronic and nearly equal in molecular mass. Explain why the boiling point of CO is slightly higher than that of N2. A. N2 can hydrogen bond. B. N2 has a larger dipole moment. C. CO is less massive. D. CO has a dipole moment. E. CO is more massive.

18. Identify the types of intermolecular forces that are present in C3H8 and CH3OCH3 and select the substance that has the highest boiling point. A. C3H8, dispersion; CH3OCH3, dispersion, dipolar; C3H8, highest boiling point B. C3H8, dispersion; CH3OCH3, dispersion, dipolar; CH3OCH3, highest boiling point C. C3H8, dispersion; CH3OCH3, dispersion; CH3OCH3, highest boiling point D. C3H8, dispersion, dipolar; CH3OCH3, dispersion, dipolar; C3H8, highest boiling point E. C3H8, dispersion; CH3OCH3, dispersion; C3H8, highest boiling point 19. Rationalize the difference in boiling points between CH2BrCl (68°C) and CH3Br (3.5°C). A. CH2BrCl does not have a dipole moment, and CH3Br has a dipole moment. B. CH2BrCl is more polarizable than CH3Br. C. CH2BrCl can hydrogen bond. D. CH2BrCl is less polarizable than CH3Br. E. CH2BrCl has a dipole moment, and CH3Br does not have a dipole moment. 20. Predict the boiling point of H2Se if the following is true for the boiling points: H2O – 100°C H2Te – -2°C H2S – -61°C A. It will have a boiling point about -32°C. B. It is impossible to estimate. C. It will have a boiling point of about -100°C. D. It will have a boiling point about 10°C. E. It will have a boiling point about 110°C. 21. Arrange the following in terms of decreasing boiling points: N2, O2, NO A. NO > N2 > O2 B. O2 > N2 > NO C. N2 > NO > O2 D. NO > O2 > N2 E. N2 > O2 > NO 22. Predict the order of the melting points (from highest to lowest) of NH3, CH4, SiH4, and GeH4. A. NH3 > CH4 > SiH4 > GeH4 B. NH3 > SiH4 > CH4 > GeH4 C. CH4 > SiH4 > GeH4 > NH3 D. GeH4 > SiH4 > CH4 > NH3 E. NH3 > GeH4 > SiH4 > CH4 23. Which one of the following is likely to be a liquid at room temperature? (i) CH4 (ii) Br2 (iii) NaCl (iv) H2O (v) H2S (vi) CH3OH A. iv and vi only B. iv, v, and vi only C. i and v only D. ii, iv, and vi only E. ii, iii, iv, and vi only

24. In which case are adhesive forces involved? A. hydrogen bonding in water B. surface tension C. capillary action D. viscosity 25. The reason that some insects can walk on water is due to: A. capillary action. B. vaporization. C. adhesive forces. D. surface tension. E. dishwashing detergent. 26. Which one of the following statements is incorrect? A. The enthalpy of deposition is more negative than the enthalpy of freezing. B. The enthalpy of sublimation is the negative of the enthalpy of deposition. C. The enthalpy of vaporization is the negative of the enthalpy of condensation. D. The enthalpy of vaporization is less than the enthalpy of melting. E. The enthalpy of sublimation is greater than the enthalpy of vaporization. 27. Which one of the following is an exothermic process? A. melting B. subliming C. freezing D. boiling E. none of the above 28. A substance above its critical temperature and pressure is known as a A. liquid. B. gas. C. supercritical fluid. D. super-cooled liquid. E. none of the above 29. Increasing the amount of liquid in a closed container will cause the vapor pressure of the liquid to: A. increase. B. remain the same. C. decrease. D. It depends on the liquid.

ANSWERS (most in BOLD) For questions 1-5 use the following choices: Hydrogen Bonding Metallic Bonding Ionic Bonding Dipole Forces London Dispersion Forces 1. What accounts for intermolecular forces in CCl4 molecules? E 2. What explains why the boiling point of Acetic acid, CH3COOH, is greater than that of Acetone, CH3COCH3? A 3. What holds solid sodium together? B 4. What holds solid ICl together? D 5. What holds Calcium Chloride together? C 6. Which of the following liquids has the highest vapor pressure at 25ºC? A. CCl4 B. H2O2 C. H2O

D. CH2Cl2 E. CHCl3 7. Which of the following is true of the critical temperature of a pure substance? A. It is the temperature above which the liquid phase can exist B. It is the temperature above which the liquid phase can not exist C. It is the temperature below which the liquid phase can not exist D. It is the temperature at which all three phases coexist E. It is the temperature at which the substance reaches, but can not go beyond, the critical pressure 8. A metal crystallizes in a face-centered cube measuring 4.00 x 102 picometers on each edge. What is the radius of the atom? A. 141 pm B. 173 pm C. 200. pm D. 282 pm E. 565 pm 9. The molecules butane and 2-methylpropane are structural isomers. Which of the following would be the same for both, assuming constant temperature where necessary? A. Boiling Point B. Vapor Pressure C. Melting Point D. Solubility E. Gas Density 10. Which of the following lists intermolecular forces in order from strongest to weakest? A. dipole attractions, dispersion forces, hydrogen bonds B. hydrogen bonds, dispersion forces, dipole attractions C. dipole attractions, hydrogen bonds, dispersion forces D. hydrogen bonds, dipole attractions, dispersion forces E. dispersion forces, hydrogen bonds, dipole attractions

11. Arrange in order of increasing boiling point: A. CH3CL, CO2, CH3OH, NaCl B. CO2, CH3Cl, CH3OH, NaCl C. CO2, CH3OH, CH3Cl, NaCl D. NaCl, CH3OH, CH3Cl, CO2 E. CH3OH, CO2, CH3Cl, NaCl 12. A metal crystallizes in a cubic lattice. The unit cell edge length is 100. picometers. The density is 200. g/cm3. The atomic mass is 60.2 g/mol. How many of these atoms are there in a unit cell? A. 1.00 B. 2.00 C. 4.00 D. 6.00 E. 12.0 13. List the three states of matter in order of increasing molecular disorder. A. liquid < gas < solid B. gas < solid < liquid C. gas < liquid < solid D. solid < liquid < gas E. liquid < solid < gas 14. Which types of intermolecular attractive forces operate between polar molecules? A. dipole-dipole attraction B. London dispersion C. London-dispersion and hydrogen bonding D. hydrogen bonding E. London dispersion and dipole-dipole attraction 15. What types of intermolecular forces can exist between neutral molecules? A. London dispersion B. dipole-dipole attraction, London dispersion, and hydrogen bonding C. dipole-dipole attraction D. hydrogen bonding E. ionic interaction 16. What kind of attractive forces must be overcome to sublime CO2? A. dipole-dipole attraction B. hydrogen bonding C. London dispersion D. van der Waals forces E. all of these 17. Molecular nitrogen, N2, and carbon monoxide, CO, are isoelectronic and nearly equal in molecular mass. Explain why the boiling point of CO is slightly higher than that of N2. A. N2 can hydrogen bond. B. N2 has a larger dipole moment. C. CO is less massive. D. CO has a dipole moment. E. CO is more massive. 18. Identify the types of intermolecular forces that are present in C3H8 and CH3OCH3 and

select the substance that has the highest boiling point. A. C3H8, dispersion; CH3OCH3, dispersion, dipolar; C3H8, highest boiling point B. C3H8, dispersion; CH3OCH3, dispersion, dipolar; CH3OCH3, highest boiling point C. C3H8, dispersion; CH3OCH3, dispersion; CH3OCH3, highest boiling point D. C3H8, dispersion, dipolar; CH3OCH3, dispersion, dipolar; C3H8, highest boiling point E. C3H8, dispersion; CH3OCH3, dispersion; C3H8, highest boiling point 19. Rationalize the difference in boiling points between CH2BrCl (68°C) and CH3Br (3.5°C). A. CH2BrCl does not have a dipole moment, and CH3Br has a dipole moment. B. CH2BrCl is more polarizable than CH3Br. C. CH2BrCl can hydrogen bond. D. CH2BrCl is less polarizable than CH3Br. E. CH2BrCl has a dipole moment, and CH3Br does not have a dipole moment. 20. Predict the boiling point of H2Se if the following is true for the boiling points: H2O – 100°C H2Te – -2°C H2S – -61°C A. It will have a boiling point about -32°C. B. It is impossible to estimate. C. It will have a boiling point of about -100°C. D. It will have a boiling point about 10°C. E. It will have a boiling point about 110°C. 21. Arrange the following in terms of decreasing boiling points: N2, O2, NO A. NO > N2 > O2 B. O2 > N2 > NO C. N2 > NO > O2 D. NO > O2 > N2 E. N2 > O2 > NO 22. Predict the order of the melting points (from highest to lowest) of NH3, CH4, SiH4, and GeH4. A. NH3 > CH4 > SiH4 > GeH4 B. NH3 > SiH4 > CH4 > GeH4 C. CH4 > SiH4 > GeH4 > NH3 D. GeH4 > SiH4 > CH4 > NH3 E. NH3 > GeH4 > SiH4 > CH4 23. Which one of the following is likely to be a liquid at room temperature? (i) CH4 (ii) Br2 (iii) NaCl (iv) H2O (v) H2S (vi) CH3OH A. iv and vi only B. iv, v, and vi only C. i and v only D. ii, iv, and vi only E. ii, iii, iv, and vi only

24. In which case are adhesive forces involved? A. hydrogen bonding in water B. surface tension C. capillary action D. viscosity 25. The reason that some insects can walk on water is due to: A. capillary action. B. vaporization. C. adhesive forces. D. surface tension. E. dishwashing detergent. 26. Which one of the following statements is incorrect? A. The enthalpy of deposition is more negative than the enthalpy of freezing. B. The enthalpy of sublimation is the negative of the enthalpy of deposition. C. The enthalpy of vaporization is the negative of the enthalpy of condensation. D. The enthalpy of vaporization is less than the enthalpy of melting. E. The enthalpy of sublimation is greater than the enthalpy of vaporization. 27. Which one of the following is an exothermic process? A. melting B. subliming C. freezing D. boiling E. none of the above 28. A substance above its critical temperature and pressure is known as a A. liquid. B. gas. C. supercritical fluid. D. super-cooled liquid. E. none of the above 29. Increasing the amount of liquid in a closed container will cause the vapor pressure of the liquid to: A. increase. B. remain the same. C. decrease. D. It depends on the liquid.