In 1928, 1.0 g of a new element was isolated from 660 kg of the ore molybdenite. The percent by mass of this element in the ore was:
A.
1.5%
B.
6.6%
C.
1.0%
D.
1.5 ´ 10–4%
E.
3.5 ´ 10–3%
2.
A titration was performed to find the concentration of hydrochloric acid with the following results:
Trial
Molarity
1
1.25 ± 0.01
2
1.24 ± 0.01
3
1.26 ± 0.01
The actual concentration of HCl was determined to be 1.000 M; the results of the titration are:
A.
both accurate and precise.
B.
accurate but imprecise.
C.
precise but inaccurate.
D.
both inaccurate and imprecise.
E.
accuracy and precision are impossible to determine with the available information.
3.
Which of the following is the least probable concerning five measurements taken in the lab?
A.
The measurements are accurate and precise.
B.
The measurements are accurate but not precise.
C.
The measurements are precise but not accurate.
D.
The measurements are neither accurate nor precise.
E.
All of these are equally probable.
4.
The amount of uncertainty in a measured quantity is determined by:
A.
both the skill of the observer and the limitations of the measuring instrument.
B.
neither the skill of the observer nor the limitations of the measuring instrument.
C.
the limitations of the measuring instrument only.
D.
the skill of the observer only.
5.
The degree of agreement among several measurements of the same quantity is called __________. It reflects the reproducibility of a given type of measurement.
A.
accuracy
B.
error
C.
precision
D.
significance
E.
certainty
6.
Manganese makes up 1.3 ´ 10–4 percent by mass of the elements found in a normal healthy body. How many grams of manganese would be found in the body of a person weighing 183 lb? (2.2 lb = 1.0 kg)
A.
1100 g
B.
0.11 g
C.
11 g
D.
0.24 g
E.
none of these is correct
7.
The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus
A.
75 protons, 75 neutrons.
B.
75 protons, 130 neutrons.
C.
130 protons, 75 neutrons.
D.
75 protons, 110 neutrons.
E.
not enough information is given.
8.
Naturally occurring iron contains 5.82%
The respective atomic masses are 53.940 amu, 55.935 amu, 56.935 amu, and 57.933 amu. Calculate the average atomic mass of iron.
Answer:
9.
What is the mass of one atom of copper in grams?
A.
63.5 g
B.
52.0 g
C.
58.9 g
D.
65.4 g
E.
1.06 × 10–22 g
10.
Iron is biologically important in the transport of oxygen by red blood cells from the lungs to the various organs of the body. In the blood of an adult human, there are approximately 2.60 ´ 1013 red blood cells with a total of 2.90 g of iron. On the average, how many iron atoms are present in each red blood cell? (molar mass (Fe) = 55.85 g)
A.
8.33 ´ 10–10
B.
1.20 ´ 109
C.
3.12 ´ 1022
D.
2.60 ´ 1013
E.
5.19 ´ 10–2
11.
What is the molar mass of ethanol (C2H5OH)?
A.
45.07
B.
38.90
C.
46.07
D.
34.17
E.
62.07
12.
Roundup, an herbicide manufactured by Monsanto, has the structure How many moles of molecules are there in a 500.-g sample of Roundup?
A.
0.338
B.
1.75
C.
2.96
D.
84.5
E.
none of these
13.
What is the coefficient for water when the following equation is balanced? As(OH)3(s) + H2SO4(aq) ® As2(SO4)3(aq) + H2O(1)
A.
1
B.
2
C.
4
D.
6
E.
12
14.
One molecule of a compound weighs 2.03 ´ 10–22 g. Its molar mass is:
A.
48.0 g/mol
B.
92.1 g/mol
C.
114 g/mol
D.
122 g/mol
E.
none of these
15.
You take an aspirin tablet (a compound consisting solely of carbon, hydrogen, and oxygen) with a mass of 1.00 g, burn it in air, and collect 2.20 g of carbon dioxide and 0.400 g water. The molar mass of aspirin is between 170 and 190 g/mol. The molecular form of aspirin is
A.
C6H8O5
B.
C9H8O4
C.
C8H10O5
D.
C10H6O4
E.
none of these
16.
The limiting reactant in a reaction
A.
has the lowest coefficient in a balanced equation.
B.
is the reactant for which you have the fewest number of moles.
C.
has the lowest ratio of moles available/coefficient in the balanced equation.
D.
has the lowest ratio of coefficient in the balanced equation/moles available.
E.
none of these
17.
Suppose the reaction Ca3(PO4)2 + 3H2SO4 ® 3CaSO4 + 2H3PO4 is carried out starting with 103 g of Ca3(PO4)2 and 75.0 g of H2SO4. How much phosphoric acid will be produced?
A.
74.9 g
B.
50.0 g
C.
112 g
D.
32.5 g
E.
97.6 g
18.
A 2.00-g sample of an oxide of bromine is converted to 2.936 g of AgBr. Calculate the empirical formula of the oxide. (molar mass for AgBr = 187.78)
A.
BrO3
B.
BrO2
C.
BrO
D.
Br2O
E.
none of these
19.
The empirical formula of styrene is CH; its molar mass is 104.1. What is the molecular formula of styrene?
A.
C2H4
B.
C8H8
C.
C10H12
D.
C6H6
E.
none of these
20.
A 0.4647-g sample of a compound known to contain only carbon, hydrogen, and oxygen was burned in oxygen to yield 0.8635 g of CO2 and 0.1767 g of H2O. What is the empirical formula of the compound?
A.
CHO
B.
C2H2O
C.
C3H3O2
D.
C6H3O2
E.
C3H6O2
21.
The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of 2.78 g of ethyl butyrate leads to formation of 6.32 g of CO2 and 2.58 g of H2O. The properties of the compound suggest that the molar mass should be between 100 and 150. What is the molecular formula?
Answer:
22.
What is the coefficient for oxygen when the following equation is balanced? NH3(g) + O2(g) ® NO2(g) + H2O(g)
A.
3
B.
6
C.
7
D.
12
E.
14
23.
When 125.0 g of ethylene (C2H4) burns in oxygen to give carbon dioxide and water, how many grams of CO2 are formed?
A.
392.2 g
B.
250.0 g
C.
57.50 g
D.
425.6 g
E.
327.0 g
24.
How many grams of H2O will be formed when 32.0 g H2 is mixed with 32.0 g O2 and allowed to react to form water?
A.
36.0 g
B.
288 g
C.
18.0 g
D.
64.0 g
E.
144 g
25.
The refining of aluminum from bauxite ore (which contains 50.% Al2O3 by mass) proceeds by the overall reaction 2Al2O3 + 3C ® 4Al + 3CO2. How much bauxite ore is required to give the 5.0 ´ 1013 g of aluminum produced each year in the United States? (Assume 100% conversion.)
A.
1.3 ´ 1013 g
B.
5.3 ´ 1013 g
C.
1.9 ´ 1014 g
D.
7.6 ´ 1014 g
26.
SO2 reacts with H2S as follows: 2H2S + SO2 ® 3S + 2H2O When 7.50 g of H2S reacts with 12.75 g of SO2, which statement applies?
A.
6.38 g of sulfur are formed.
B.
10.6 g of sulfur are formed.
C.
0.0216 moles of H2S remain.
D.
1.13 g of H2S remain.
E.
SO2 is the limiting reagent.
27.
One of the major commercial uses of sulfuric acid is in the production of phosphoric acid and calcium sulfate. The phosphoric acid is used for fertilizer. The reaction is Ca3(PO4)2 + 3H2SO4 ® 3CaSO4 + 2H3PO4. What mass of concentrated H2SO4 (98% by mass) must be used to react completely with 100.00 g of calcium phosphate?
Answer:
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The respective atomic masses are 53.940 amu, 55.935 amu, 56.935 amu, and 57.933 amu. Calculate the average atomic mass of iron.
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