chemistery
CHEM 2100—Homework #1
Due:
Wednesday February 10th by 11:59 p.m.
NAME: (
46
points)
(1) (4 pts) Indicate the correct number of significant figures for the following numbers:
204 _______________
0.0089802 _______________
3.020 x 10−9 _______________
1000 _______________
670.0 _______________
88 _______________
0.106010 _______________
2180. _______________
(2) (4 pts) Perform the following calculations reporting the final answer with the correct number of significant figures.
35
4.23 + 48.782 +98.67902 _____________
8.864 – 6.2 + 24.26 _____________
89.127 x 5.37 _____________
100.21 x 0.38 _____________
50
18/17.252 _____________
(4.47 x103 + 1.6 x 102)/8.54234 x 105 _____________
(0.971 – 0.43)/(8.1 + 65.176) _____________
(3288/64.86) + (26.0 x 9) _____________
(3) (2 pts) In a piece of scientific equipment is it better to be precise or accurate? Defend your answer.
(4) (5 pts) According to the world atlas Rhode Island is the smallest US state with a land area of 1,033.81 square miles. If it rains on the entire state a total of 2.5 inches how many liters of water fell as rainfall? If one raindrop is 0.50 mL how many individual raindrops fell?
(5) (5 pts) The top cruising speed of the SR-71 Blackbird was Mach 3.17 or 2,432.24 miles per hour. How many minutes would it take the Blackbird to fly from San Bernardino, CA to New York City? A distance of 4,417.81 kilometers.
(6) (4 pts) A kilogram of solid Platinum costs $30,993.32. If the density of Platinum is 21.45 g/cm3 what would the dimensions of a cube be that weighed 1.00 kilogram?
(7) (4 pts) Indium (In) consists of two main isotopes, 113In (112.904058 amu) and 115In (114.903878 amu). If the atomic weight of In is 114.818 amu what are the relative abundances of the two isotopes? [Report your answers to 2 decimal places]
(8) (4 pts) Zinc consists of 5 main isotopes.
64Zn
at 48.63%,
66Zn
at 27.90%,
67Zn
at 4.10%,
68Zn
at 18.75%, and
70Zn
at 0.62%. Using the isotope masses found in the table below calculate the atomic mass of Zinc.
|
Isotope |
Mass, amu |
| 64Zn |
63.9296011 |
| 66Zn |
65.9260368 |
| 67Zn |
66.9271309 |
| 68Zn |
67.9248476 |
| 70Zn |
69 .925325 |
(9) (2 pts) Indicate whether the following ions have a noble-gas electron arrangement.
Ti3+ ______________
Mn7+ ______________
Pb3+ ______________
As3− ______________
(10) (4 pts) Give the correct name for the following compounds.
Fe2(CO3)3 __________________
S4O10 __________________
KMnO4 __________________
H2S __________________
N2O5 __________________
PbCl2 __________________
Ag2Cr2O7 __________________
HClO __________________
(11) (4 pts) Give the correct chemical formula for the following compounds.
Sodium hypobromite ___________
Chromium (III) acetate ___________
Chloric acid ___________
Dinitrogen tetroxide ___________
Cobalt (II) hydrogen carbonate ___________
Zinc Nitrate ___________
Ammonia ___________
Ammonium __ ________
(12) (4 pts) Fill in the missing pieces of the following table:
|
Symbol |
31P3− |
|
|
Protons |
35 | 50 |
|
Neutrons |
44 |
69 |
|
Electrons |
46 | |
|
Mass # |
||
|
Net Charge |
−1 |