PRACTICE QUESTIONS FOR EXAM I Spring 2014 This has been updated after Monday s lecture (2/17/14)

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1 Page 1 Chem 123 PRACTICE QUESTINS FR EXAM I Spring 2014 This has been updated after Monday s lecture (2/17/14) I AM NT PRVIDING ANSWERS T THESE. PLEASE REVIEW YUR TEXTBK AND LECTURE NTES IF YU DN T KNW THE ANSWERS. WE HAVE CVERED ALL THE TPICS IN LECTURE. PLEASE NTE THAT THESE PRACTICE QUESTINS ARE PRVIDED JUST T SHW YU WHAT YUR EXAM MAY LK LIKE. THEY D NT CVER ALL THE MATERIAL YU SHULD KNW FR YUR EXAM I. YU SHULD KNW THE ANSWERS F ALL THESE QUESTINS BUT THERE CERTAINLY WILL BE QUESTINS N YUR EXAM THAT D NT APPEAR HERE. These are practice questions. This is not meant to show you the length of the exam. bviously there are more questions here than you can answer in an one-hour exam. THESE ARE THE EQUATINS AND CNSTANTS THAT WILL BE PRVIDED N EXAMS. As usual, a periodic table will also be provided. R = J mol 1 K 1 R = atm L mol 1 K 1 Ideal gas law equation will not be provided...you should know it. Equations provided on exam (no need to memorize): ΔHvap 1 ln P= + C R T P1 ΔHvap 1 1 ln = P R T T Gen Chem I review material (about 15% of exam) Nomenclature (about 10% of exam) rganic Molecules, Logarithm, & Chapter 12 (about 75% of exam) NTE: Wiley Review #2 provide ADDITINAL practice questions for crystal structures. Practice questions on nomenclature are not provided here. Refer to Nomenclature Reviews A, B, C, D 1. When comparing atoms of two elements the one with the higher first ionization energy should be A. smaller in size B. larger in size 2. Which atom is larger? A. phosphorus B. sulfur 3. Which is more electronegative? A. sulfur B. nitrogen 4. Which of the following is a molecule? (Circle as many as applies.) A. Hf B. P 4 C. P 3 D. He E. Fe Which has a higher ionization energy? A. metals B. nonmetals 6. What are alloys? A. They are the elements along the border between metals and nonmetals in the periodic table. B. They are compounds of metals. C. They are homogeneous mixtures of metals. D. They are compounds of aluminum. 7. The following questions concern selenium (atomic number 34). A. Give its full electron configuration. Circle its valence electrons in the configuration.

2 Page 2 B. Give it electron configuration using the Core Method. C. Give its electron dot symbol H H H N C C C N: H A B C Give the hybridization, the bond angle and state the geometry at each of the above atoms: Hybridization Bond Angle Geometry (name in one or two words) A B C What is the total number of bonds in this molecule? Ans. What is the total number of bonds in this molecule? Ans. 9. Draw the resonance structures of C 3 2. Draw the resonance hybrid of C 3 2. If we were able to measure its dipole moment, would you expect it to be zero or larger than zero? Ans. 10. Give the full structure of (showing all atoms, bonds and lone pairs) a) benzene b) acetic acid c) acetone 11. Which has the higher viscosity? (Assume they are of comparable size.) A. CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 B. CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 H 12. Which do we expect to have the higher boiling point? A. B. H 3 C N CH 3 H 3 C C H CH 3 CH 3 NH Which should have the higher surface tension? A. substance with a higher vapor pressure B. substance with a lower vapor pressure 14. Which is a better solvent for CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 A. H 2 B. benzene C. CH 3 CH 2 CH 2 CH 2 H Pressure 15. Which has the higher vapor pressure at a given temperature? A. H 2 (l) B. H 2 S (l) 16. Which of the following affects the vapor pressure of a liquid? A. the surface area of the liquid B. the volume of the liquid C. the temperature of the liquid D. all of the above E. none of the above 17. In the graph shown on the right showing the vapor pressure of acetic acid and ether. Temperature

3 Page 3 Acetic acid is CH 3 C 2 H and ether is CH 3 CH 2 CH 2 CH 3 and considered similar in molecular weight. Which curve corresponds to acetic acid? A. Curve A Curve B P A B T 18 Which pair of solute and solvent is most likely to form a solution? A. CCl 4 in H 2 B. NaCl in benzene C. benzene in C 6 H Ethanol (C 2 H 5 H) and water (H 2 ) are both liquids at or near room temperature. When a sample of ethanol is poured into a beaker containing water, the two liquids are A. immiscible because organic and non-organic compounds cannot mix. B. immiscible because each has strong hydrogen bonds that cannot be broken. C. miscible because both are liquids and all liquids are miscible. D. miscible because each can hydrogen bond with the other. 20. State what forces are broken when these substances melt. If there is more than one, state all of them. A. C H 3 N CH 3 CH 3 B. CCl 4 C. HF D. C 2 subliming E. table salt 21. Draw three Lewis structures of ammonia (NH 3 ) and show exactly where the hydrogen bonding is. 22. Carefully explain how a nonpolar molecule such as Br 2 can be attracted to another Br 2 molecule. Use full sentences and Lewis structures in your explanation. 23. NaCl has a molar mass of 58 g/mol and heptane (C 7 H 16 ) has a molar mass of 100 g/mol. Explain why NaCl is a solid but heptane is a liquid even though heptane is much larger. Use full sentences. 24. When an ionic compound dissolves in water the ions are surrounded by water molecules. Draw three water molecules around each ion, showing how the water molecules would be oriented with respect to the ion. Water is to be drawn thus: K + Br 25. NaCl has a molar mass of 58 g/mol and heptane (C 7 H 16 ) has a molar mass of 100 g/mol. Explain why NaCl is a solid but heptane is a liquid even though heptane is much larger. Use full sentences. H H 26. Give the molecular formula of the following:

4 Page 4 H A B C What type of intermolecular forces would you expect these to exhibit? Which is the dominant intermolecular force for each of these? 27. a) Name the type of organic molecule each of the following belongs: (hydrocarbon? alcohol? etc.) H NH 2 A B C b) Name the predominant intermolecular forces for each of the above. 28. Draw structures to show where the ion-dipole force is in an aqueous solution of KBr. 29. What information does X-ray diffraction give us? A. molecular weight of a substance B. radioactivity of the substance C. size of the atom D. color of the substance H Hvap (4 pts) The Clausius equation is lnp C R T A graph is plotted for ln P versus 1/T and the slope was determined to be 3 K. Calculate the heat of vaporization H vap in units of kj/mol. R is J/(K.mol) Show your setup carefully, including units at every step. 31. Give log 3.15x10 4 to the correct sig. fig. Ans ln x = , what is x? Ans in the correct sig. fig. Ans If your answers do not match what is provided here, please review the PowerPoint on logarithm before you come to ask me. 32. How much heat is needed to warm 78.6g of H 2 from 35 C to 130 C? Given: Specific heat for ice = J g 1 C 1 Specific heat for water = 4.18 J g 1 C 1 Specific heat for steam = J g 1 C 1 Heat of fusion for H 2 = 6.01 kj/mol Heat of vaporization for H 2 = kj/mol 33. Which compound cannot be liquefied by compression at temperature of 25.0 C? A. C 2 H 4, critical point: 9.9 C, 50.5 atm B. CH 3 Cl, critical point: C, 66.0 atm C. C 2 H 2, critical point: 35.5 C, 61.6 atm D. C 2 H 6, critical point: 32.2 C, 48.2 atm E. S 2, critical point: C, 78.0 atm

5 Page (2 pts) Below is the heating curve of a substance Temp E D B C A Heat added a) Which part of the graph shows the substance existing as a liquid and gas at the same time? (CIRCLE NE) A B C D E b) Explain why the temperature remains constant in section B even though heat is still be added to the system. c). Explain in full sentences for Sections B and D on the graph, even though heat is still being added, why the temperature does not go up. Where did all that energy go? 35. Review Paper HW#1 on energetics of phases changes. (answers already posted) 36. A substance has a high melting point and is brittle. Which of the following would fit this description? A. Zn B. Br 2 C. KBr 37. P 760 torr Temp Carefully label the following on the phase diagram shown above: solid phase, liquid phase, gas phase the critical point the normal boiling point on the x-axis the normal melting point on the x-axis What happens to the melting point when the pressure is increased? A. It is increased B. It is decreased For this substance, is the solid or the liquid more dense? A. the solid B. the liquid What happens to the boiling point when pressure is increased? A. It is increased B. It is decreased If the solid is less dense than the liquid would the melting point increase or decrease when the pressure is increased? A. MP increases B. MP decreases

6 Page 6 The following types of questions have been covered on Monday s lecture. 38. Nickel has a face-centered cubic unit cell with a length of 324 pm along an edge. What is the radius of the nickel atom? (See diagram on the right.) Note typo error. Edge is 324 pm not 32.4 pm Ans. 115 pm What is the volume of the unit cell of Ni in ml? Ans. 3.40x10 23 ml 39. A new compound, vitellium oxide, has been discovered. X-ray crystallographic studies reveal that it has a cubic unit cell with a vitellium ion at each of the corner lattice points, a vitellium ion at the geometric center of the unit cell, and an oxide ion in the center of each of the cube faces in the unit cell. How many vitellium ions are there per cubic cell? How many oxide ions are there per cubic cell? Based on this structure, the correct formula should be A. Vi 3 B. Vi 3 2 C. Vi D. Vi 2 3 E. Vi 3 Wiley Review #2 has been posted for additional practice on crystal structures.

What is the volume of the unit cell of Ni in ml?

What is the volume of the unit cell of Ni in ml? P a g e 1 Chem 123 Practice Questions for EXAM II Fall 2014 Exam II on Mon 10/13/14 This HAS BEEN updated after Wed s lecture (10/8/14) JUST studying these questions is not sufficient preparation. There