Chem. 1C Midterm 1 Practice Test 2

Transcription

1 Chem. 1C Midterm 1 Practice Test 2 First initial of last name Name Student Number All work must be shown on the exam for partial credit. Points will be taken off for incorrect or no units. Calculators are allowed. Cell phones may not be used for calculators. On fundamental and short answer problems you must show your work in order to receive credit for the problem. If your cell phone goes off during the exam you will have your exam removed from you. Fundamentals (of 36 possible) Problem 1 (of 7 possible) Problem 2 (of 21 possible) Multiple Choice (of 36 possible) Midterm Total (of 100 possible) 1

2 Fundamental Questions Each of these fundamental chemistry questions is worth 6 points. You must show work to get credit. Little to no partial credit will be rewarded. Make sure to include the correct units on your answers. 1) 6 pts Determine the bond angle for the numbered bonds: 1) 2) 3) 3) 6 pts Circle the formula that best fits each of the following descriptions: Greatest viscosity: CH 3 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 OH HOCH 2 CH 2 OH Higher vapor pressure at 1 atm, 25 C: CH 3 OCH 3 CH 3 CH 2 OH H 2 O Lowest freezing point: H 2 O O 2 He CO 2 3) 6 pts What is the boiling point of water in Denver if atmospheric pressure is 0.82 atm, and ΔH vap =40.7 4) 6 pts How are the local electron model and molecular theory similar? How are they different? (75 words or less) 2

3 5) 6 pts Identify the kinds of intermolecular forces that might arise between molecules of each of the following substances: CH 3 NH 2 PCl 3 PCl 5 6) 6 pts Study the following phase diagram of Substance X. If a sample of pure X is to be a mixture of liquid and gas, which point marks the lowest possible temperature and pressure of the sample? If a sample of pure X is a gas, in which region must the temperature and pressure be? Which line must the temperature and pressure have crossed if a solid sample of X is observed to melt? 3

4 Short Answer Questions Each of the following short answer questions are worth the noted points. Partial credit will be given. You must show your work to get credit. Make sure include proper units on your answer. 1) 7 pts You are given a small bar of an unknown metal X. You find the density of the metal to be An x-ray diffraction experiment measures the edge of face-centered cubic unit cell at 4.09Ȧ (1 Ȧ = m). Identify the metal. 4

5 2a) 7 pts 1) Identify the electronic structure of ICl ) Identify the molecular structure of ICl ) Identify the polarity of ICl ) What method did you use to determine these answers? 2b) 7 pts 1) What is the hybridization of all of the atoms in HCN? 2) Determine the number of σ and π bonds in HCN? 3) What orbital(s) overlap to make the bond(s) between the C and the N? 4) What method did you use to determine these answers? 2c) 7 pts 1) What is the electron configuration NO + (fills like N 2 )? 2) What is the bond order for NO +? 3) Is NO + diamagnetic or paramagnetic? 4) What method did you use to determine these answers? 5

6 Multiple Choice Questions Each of the following multiple choice questions are worth 6 points. Your answers need to be filled in on the Scantron provided. Note: Your Scantrons will not be returned to you, therefore, for your records, you may want to mark your answers on this sheet. On the Scantron you need to fill in your perm number, test version, and name. Failure to do any of these things will result in the loss of 1 point. Your perm number is placed and bubbled in under the ID number. Do not skip boxes or put in a hyphen. In addition, leave bubbles blank under any unused boxes. The version number (A) is bubbled in under the test form. 1. Which of the following is polar? A) XeO 2 B) I 3 C) XeF 2 D) NON E) ICl 4 2. Which statement regarding water is true? A) Liquid water is less dense than solid water. B) Only covalent bonds are broken when ice melts. C) Hydrogen bonds are stronger than covalent bonds. D) Energy must be given off in order to break down the crystal lattice of ice to a liquid. E) All of these statements are false. 3. How many of the following molecules have all of their atoms in the same plane? H 2 C = CH 2 F 2 O H 2 CO NH 3 CO 2 BeCl 2 H 2 C=C=CH 2 A) 5 B) 3 C) 6 D) 4 E) None of the above 6

7 4. The normal boiling point of the substance with the phase diagram shown below is C. A) 50 B) 10 C) 15 D) 40 E) None of the above 5. As the bond order of a bond increases, its bond energy and its bond length. A) decreases, decreases B) increases, decreases C) decreases, increases D) increases, increases 6. Which of the following statements is correct?? A) More than one of these statements are correct. B) Free rotation may occur about a double bond. C) bonds have electron density on the internuclear axis. D) A triple bond is composed of two bonds and one bond. E) bonds result from the head-to-head overlap of atomic orbitals. 7