CHE 113 Review & Preparatory Assignment
Review of General Chemistry Assignment:
Use a general chemistry textbook (such as the one you used for 1st semester general chemistry) to review bonding (including electronegativity, polarity of bonds, and hybrid orbitals) and Lewis Dot Structures (including resonance). Be able to use these structures to predict the shapes and polarities of molecules, and intermolecular forces (London dispersion forces, dipole forces, and hydrogen ‘bonding’). These are crucial concepts as we begin our study of organic chemistry. As far as our lab work, please review significant figures, metric conversions, and stoichiometry (including limiting reactant problems). Then do the following problems to be sure you understand these concepts. Answers are provided by a hyperlink. Please neatly show all of your work to support your answers.
Preparatory Assignment:
Read Chapter 1 of our textbook by Bettelheim, et al, 6th ed. Do the problems with answers through 1.25. (Answers are in the back of the textbook.)
Review
of General Chemistry Assignment:
Draw all Lewis dot structures to support your answers for questions 1 - 4.
1. In the Lewis dot structure for N2, each N atom has
a) 1bonding pair of electrons and 3 nonbonding pairs.
b) 2 bonding pairs of electrons and 2 nonbonding pairs.
c) 3 bonding pairs of electrons and 1 nonbonding pair.
d) none of these
2.Which of the following species -- BF3, CO32-, O3 -- exhibits resonance?
a) CO32- only.
b) CO32- and O3.
c) all of them
d) none of them
3. The shape of the SO2 molecule is
a) linear
b) bent at about 109º.
c) bent at about 120º.
d) none of these.
4.The shape of the NH3 molecule is
a) triangular pyramidal
b) trigonal (triangular) planar
c) T-shaped
d) none of these
5. Consider the molecule HC≡CCl. What kind of hybrid orbitals are used by the carbon atoms?
a) sp
b) sp2
c) sp3
d) none of these
6. When an atom hybridizes its orbitals to sp3 orbitals, how many are there?
a) two
b) three
c) four
d) none of these
7. What are the angles between sp2 hybrid orbitals?
a) 120º
b) 109º
c) 180º
d) none of these
For each of the molecules in questions 8 – 13, draw its Lewis dot structure and then state its major intermolecular force (London dispersion force, dipole force, or hydrogen ‘bonding’).
8. I2
9. NO
10. HCl
11. SO3
12. CO2
13. HF
For each pair of molecules in questions 14 – 16, predict which has the higher boiling point by considering the relative strengths of its intermolecular forces. (Draw Lewis dot structures for any molecules for which you have not already done so.)
14. HCl and HF
15. NO and O2
16. H2S and H2Se
Change the following numbers to 4 significant figures.
17. 2.35550
18. 2.35450
19. 0.000657030
20. 213.25
21. 3.2181 x 103
22.12,341,123
How many significant figures are in each of the following numbers?
23. 3.141 m
24. 0.002004 kg
25. 23.123000 g
26.149 mL
27.1700 cm
28. 1900.00 g
29. 6.0231 x 1023 atoms
Give the answer with the correct number of significant
figures.
30. 1.86 / 2.1 =
31. (37.2) (3.141) =
32. (998) (32.15) / 21 =
33. 4.51545 / 1.05 =
34. 621 / (3.151 x 105)
35. 104 + 37.2 –18.57 =
36. 87.6 – 0.005 =
37. 6.23 + 915 – 1012.7 =
38. 87.9 + 11.3 + 9.6 =
39. 324.55 – (6104.5 / 22.3) =
40. [ (31.8) (2.4) / 8.92] – 0.17 =
41. 1.32 + 0.006 + 34 /47 =
Calculate the number of moles.
42. 4.02 g of C2H5OH
43. 24.0 g of C6H6
Calculate the number of grams.
44. 4.0 moles of CH3(CH2)3CH3
45. 0.55 moles of CH2=CH2
Consider the following chemical reaction for questions 46 - 48:
C2H4 + 3O2 à 2CO2 + 2H2O
46. Calculate the mass in grams of CO2 produced from 10.0 g C2H4 reacting with excess O2.
47. If 10.0 g of O2 and 10.0 g of C2H4 react, which reactant will be the limiting reactant? How many grams of CO2 could be produced (i.e., the theoretical yield)
48. If 8.11 g of CO2 are actually produced in the scenario of #47, what is the percent yield?