ChemWorks #1
Chapters 1-4, and 19.2
Chemistry 101
S. Bakshandeh
1. A 14-karat gold ring contains 58.30% gold by mass and weighs 12.41g. If gold sells $1232.00 per ounce, what is
the value of gold in this ring?
a. $464
b. $540
c. $924
d. $235.6
e. $314.4
f. None of these. The correct answer is $____________
2. Which of the following occupies the most volume? (Look up any information you may need to solve for this
problem, and state your source)
a. 200 mL of methanol
b. 1.36 kg of mercury
c. 5.07 fluid ounce of water
d. 4.50 lb of gold
3. An atom has 28 neutrons. Its cation with a +3 charge has 21 electrons. What is the symbol for this ion?
49 3+
3+
3+
3+
3+
a. 25
b. 28
c. 28
d. 52
e. 21
𝑆𝑐
28𝑁𝑖
21𝑆𝑐
24𝐶𝑟
24𝐶𝑟
4. An element has 5 stable isotopes. The mass and percentage of each are:
89.9043
51.46%
90.9053
11.23%
91.9046
17.11%
93.9061
17.40%
95.9082
2.80%
The element is which of the following?
a. Nb
b. Y
c. Zr
d. Sr
e. Rb
5. The name of which compound ends in “ite”?
a. HIO3
b. Na2SO3
c. H2SO3
d. Na2CO3
e. CaH2
6. The name of which compound ends in “ate”?
a. HBrO3
b. H2SO3
c. Na2SeO3
d. Na3AlO3
e. Na2S
7. The name of which compound does NOT end in ‘ide”?
a. HCl
b. HCN
c. Fe(CN)2
d. NaSCN
e. NF3
8. When a sample of 6.853 mg of a hormone was burned in a combustion analysis, 19.73 mg CO2 and 6.391 mg of
H2O were obtained. The compound was found to contain only C, H, and N, hand have a formula mass of 290.
What is the empirical formula? What is the molecular formula?
a. C9H21O/ C18H42O2
b. C10H16O/ C20H18O2
c. C19H30O2 / C19H30O2)
d. C9H21O/ C18H42O2
e. Need more information
9. Nitroglycerin, can be prepared by carefully controlled reaction of glycerol with nitric acid, according to the
equation,
C3H8O3 + 3 HNO3 → C3H5N3O9 + 3 H2O
What mass of nitric acid is required for the production of 2.8 g of nitroglycerin, if the process has a 67% yield?
a. 1.9 g
b. 3.4 g
c. 4.2 g
d. 4.5 g
e. 10. g
f. 1.0 g
10. Potassium permanganate reacts with potassium iodide in presence of sulfuric acid to produce elemental iodine.
The unbalanced net ionic equation (NIE) for this reaction is; MnO4— + I— →Mn2+ + I2
Write the balanced net ionic equation for this reaction. Use half-reaction method and show both oxidation and
reduction half-reactions.
11. Chromium in its +6 oxidation state (such as dichromate ion) is a hazardous carcinogen, while chromium (II) is
harmless. One way to destruct chromium (VI) is to reduce it to chromium (II) by reacting it with a metal like zinc
in presence of sulfuric acid. If 1.0 mol of potassium dichromate is mixed with 1.0 mol Zn and 500.0 mL of 2.0 M
sulfuric acid, what is the limiting reagent, and what is the theoretical yield of chromium (II) sulfate?
a. Zn, 0.50 mol
b. K2Cr2O7, 2.0 mol
c. H2O, 1.0 mol
d. H2SO4, 0.29 mol
e. No limiting reagent, 1.0 mol
12. Atomic mass of magnesium is 24.3050 amu and has 3 stable isotopes with masses of 23.98504, 24.98584, and
25.98259 amu, respectively. The natural abundance of Mg—25 is found to be 10.13%. What are the percentages
of the other two isotopes?
a. 73.70% and 16.17 %
b. 78.93% and 10.94%
c. 32.24% and 57.63%
d. 78.70% and 21.30%
e. 44.94% and 44.93%
f. 83.63% and 15.36%
13. 4.573 g of a compound of carbon, hydrogen, oxygen, and silver was burned in air, yielding 6.152 g of CO2, 0.8996
g H2O, and a mixture of silver and silver oxide. Because the production of this mixture yielded an indeterminate
value for amount of silver, another sample of the compound weighing 8.125 g was reacted with a solution of
NaCl, yielding 5.085 g of AgCl. What is the empirical formula of the compound?
a. C5H5OAg
b. C7H5O2Ag
c. C7H7O2Ag
d. C8H5OAg
e. C6H6OAg