Chapter 6 Practice Questions

1) The chemical formula clearly indicates the relationship between the mass of each element in
the formula.
false
2) Mass is used as a method of counting atomstrue
3) One hundred nickels must have the same mass as one hundred pennies.false
4) The numerical value of the mole is defined as being equal to the number of atoms in exactly
12 grams of pure carbon-12.
false
5) The mole has a value of 6.023 × 1022false
6) Avogadro’s Number is 6.022 × 1023.true
7) The number 6.022 × 1023 is six times larger than the number 6.022 × 1022.false
8) The lighter the atom, the less mass in one mole of that atom.true
9) One mole of argon has more atoms in it than one mole of neon.false
10) One mole of nitrogen gas contains (2) × (6.022 × 1023) nitrogen atoms.true
11) One mole of zinc contains 65.39 zinc atoms.false
12) One mole of copper atoms is 6.022 × 1023 copper atomstrue
13) The mass of 2.0 moles of H2O is greater than the mass of 1.0 mole of CO2.false
15) Two moles of cobalt atoms have a mass of 117.87 gramstrue
16) Six grams of carbon contains 3.008 × 1023 atoms.true
17) One mole of I2 has more atoms in it than one mole of Na.true
18) One mole of CO2 gas contains 1 mole of carbon atoms and 2 moles of oxygen atoms.true
19) The molar mass of a compound in grams per mole is numerically equal to the formula mass
of the compound in atomic mass units.
true
20) One mole of water contains 16 grams of oxygen atoms.true
21) One mole of water contains 6.022 × 1023 hydrogen atomsfalse
22) There are 6 grams of carbon in 22 grams of carbon dioxide.true
23) The molar mass of a compound serves as a conversion factor between grams and moles.true
24) One mole of lead(II) nitrate contains six moles of oxygen atoms.true
25) The chemical formula CuBr2 indicates that this compound is composed of 1 gram of copper
and 2 grams of bromine.
false
26) The correct formula for calculating mass percent of X in compound XY is: MASS OF X/MASS OF Y
= Mass % X
false
27) Water is 11.2% hydrogen by mass.true
28) C2H3O2 could be an empirical formula.true
29) c2h6o3 could be an empirical formula.true
30) C2H6O4 could be an empirical formula.false
31) An empirical formula gives the specific number of each type of atom in a molecule.false
32) An empirical formula gives the smallest whole number ratio of each type of atom in a
molecule.
true
33) The empirical formula for C6H6 is c3h3.false
34) The molecular formula is equal to the empirical formula multiplied by a whole number
integer
true
35) A molecule that has an empirical formula of HO and a molar mass of 34.02 gram must have
a molecular formula of H2O2.
true
36) The empirical formula mass is 18.0 and the molecular formula mass is 90, therefore n = 5.true
37) The empirical formula mass must be 25.0 if the molecular formula mass is 250 and n = 5.false
1) What is the correct value for Avogadro’s number?
A) 6.022 × 1023
B) 6.022 × 1033
C) 6.023 × 1022
D) 6.022 × 102.3
E) none of the above
A) 6.022 × 1023
2) One half of a mole of atoms would contain how many atoms?
A) 0.5
B) 3.011 × 1023
C) 6.022 × 1023
D) 6.022 × 1011.5
E) none of the above
B) 3.011 × 1023
3) Which of the following statements about the mole is FALSE?
A) One mole of atoms makes up an amount of atoms that can be seen with the naked eye.
B) A mole of a monatomic element corresponds to one Avogadro’s number of atoms.
C) One mole of a monatomic element has a mass equal to its atomic mass expressed in grams.
D) One mole of water contains 1/2 mole of oxygen atoms.
E) none of the above
D) One mole of water contains 1/2 mole of oxygen atoms.
4) How many atoms are in 5.80 moles of He?
A) 6.02 × 1023
B) 1.03 × 1023
C) 4.00
D) 3.49 × 1024
E) none of the above
D) 3.49 × 1024
5) How many atoms are in 1.50 moles of fluorine gas?
A) 6.022 × 1023
B) 9.03 × 1023
C) 18.98
D) 1.81 × 1024
E) none of the above
D) 1.81 × 1024
6) How many moles of Cu are in 1.48 × 1025 Cu atoms?
A) 0.0408
B) 24.6
C) 1.54 × 1025
D) 6.022 × 1023
E) none of the above
B) 24.6
7) One mole of boron has a mass of ________ g.
A) 9.012
B) 6.022 × 1023
C) 5
D) 10.811
E) none of the above
D) 10.811
8) One mole of oxygen gas has a mass of ________ g.
A) 16.0
B) 32.0
C) 6.022 × 1023
D) 8
E) none of the above
B) 32.0
9) What is the mass in grams of 5.40 moles of lithium?
A) 6.94
B) 37.5
C) 1.29
D) 3.25 × 1024
E) none of the above
B) 37.5
10) What is the mass of 0.560 moles of chlorine gas?
A) 19.9
B) 63.3
C) 127
D) 39.7
E) none of the above
D) 39.7
11) You have 10.0 g each of Na, C, Pb, Cu and Ne. Which contains the largest number of moles?
A) Na
B) C
C) Pb
D) Cu
E) Ne
B) C
12) You have 10.0 g each of Na, C, Pb, Cu and Ne. Which contains the smallest number of
moles?
A) Na
B) C
C) Pb
D) Cu
E) Ne
B) C
13) How many moles of iron are contained in 1.75 kg of iron?
A) 3.13 × 10-2
B) 3.13 × 10-4
C) 31.3
D) 3.13 × 104
E) none of the above
C) 31.3
14) How many moles are there in 17.5 grams of sodium?
A) 22.99
B) 1.05 × 1025
C) 0.761
D) 1.31
E) none of the above
C) 0.761
15) How many moles are there in 82.5 grams of iron?
A) 4.97 × 1025
B) 55.85
C) 0.677
D) 1.48
E) none of the above
D) 1.48
16) How many moles of bromine gas are in 37.7 grams?
A) 0.236
B) 0.472
C) 3.01 × 103
D) 79.9
E) none of the above
A) 0.236
17) How many atoms are in 15.6 grams of silicon?
A) 2.64 × 1026
B) 3.34 × 1023
C) 0.555
D) 438
E) none of the above
B) 3.34 × 1023
18) How many hydrogen atoms are in 35.0 grams of hydrogen gas?
A) 4.25 × 1025
B) 2.09 × 1025
C) 2.12 × 1025
D) 1.05 × 1025
E) none of the above
D) 1.05 × 1025
19) What is the mass of 3.09 × 1024 atoms of sulfur in grams?
A) 9.64 × 1022
B) 9.91 × 1025
C) 165
D) 0.160
E) none of the above
C) 165
20) How many moles of Pb are in 4.71 × 1021 Pb atoms?
A) 0.00782
B) 2.84 × 1045
C) 207.2
D) 6.022 × 1023
E) none of the above
A) 0.00782
21) What is the mass of 1.56 × 1021 atoms of magnesium in grams?
A) 4.72 × 10-5
B) 0.0630
C) 0.142
D) 1.07 × 10-4
E) none of the above
B) 0.0630
22) In comparing a balloon containing 25 grams of helium to a balloon containing 25 grams of
neon, which one of the following statements is TRUE?
A) Each balloon has an equal number of atoms.
B) The helium balloon has more atoms.
C) The neon balloon has more atoms.
D) This scenario cannot happen because gases have no mass.
E) none of the above
B) The helium balloon has more atoms.
23) In comparing 1 mole of carbon atoms to one mole of magnesium atoms, which statement is
TRUE?
A) The mass of 1 mole of carbon is greater than the mass of 1 mole of magnesium.
B) The mass of 1 mole of magnesium is greater than the mass of 1 mole of carbon.
C) The mass of 1 mole of carbon is the same as the mass of 1 mole of magnesium.
D) There are more atoms in 1 mole of magnesium than in 1 mole of carbon.
E) none of the above
B) The mass of 1 mole of magnesium is greater than the mass of 1 mole of carbon.
24) Which of the following contains 9.02 × 1023 atoms?
A) 4.00 g H2
B) 9.00 g H2O
C) 28.0 g N2
D) 32.0 g O2
E) none of the above
B) 9.00 g H2O
25) The mass of one mole of carbon dioxide is ________ g.
A) 28.01
B) 384.4
C) 32.00
D) 44.01
E) none of the above
D) 44.01
26) What is the molar mass of aluminum sulfate?
A) 123.0 g/mol
B) 278.0 g/mol
C) 306.2 g/mol
D) 315.2 g/mol
E) 342.2 g/mol
E) 342.2 g/mol
27) Calculate the molar mass of ammonium carbonate.
A) 78.05 g/mol
B) 88.05 g/mol
C) 96.09 g/mol
D) 112.09 g/mol
E) none of the above
C) 96.09 g/mol
28) Calculate the molar mass of calcium nitrate.
A) 136.03 g/mol
B) 102.09 g/mol
C) 132.10 g/mol
D) 164.10 g/mol
E) none of the above
D) 164.10 g/mol
29) How many molecules of sulfur trioxide are in 78.0 grams?
A) 5.87 × 1023
B) 7.33 × 1023
C) 3.76 × 1027
D) 0.974
E) none of the above
A) 5.87 × 1023
30) How many molecules of nitrogen monoxide are in a 22.5 gram sample?
A) 5.86 × 1023
B) 7.33 × 1023
C) 4.51 × 1023
D) 4.06 × 1023
E) none of the above
C) 4.51 × 1023
31) If 3.011 × 1023molecules have a mass of 20.04 grams, what is the molar mass of this
substance?
A) 40.08 g/mol
B) 10.02 g/mol
C) 20.04 g/mol
D) 6.658 × 10-23g/mol
E) none of the above
A) 40.08 g/mol
32) If 2.01 × 1023 atoms of an element from Group IA of the periodic table has a mass of 7.675
grams, this element is most likely:
A) Li.
B) Na.
C) K.
D) Rb.
E) Cs.
B) Na.
33) One mole of (NH4)2HPO4 contains how many moles of hydrogen atoms?
A) 4
B) 2
C) 8
D) 9
E) none of the above
D) 9
34) One mole of ammonium nitrate contains:
A) 3 moles of hydrogen.
B) 2 moles of oxygen.
C) 2 moles of nitrogen.
D) 1 mole of nitrogen.
E) none of the above
C) 2 moles of nitrogen.
35) One mole of ammonium nitrite contains:
A) 2 moles of nitrogen atoms.
B) 4 moles of hydrogen atoms.
C) 2 moles of oxygen atoms.
D) All of A, B, and C.
E) None of A, B, and C.
D) All of A, B, and C.
36) One mole of potassium sulfate contains:
A) 4 moles of oxygen.
B) 2 moles of sulfur.
C) 1 mole of potassium.
D) 3 moles of potassium.
E) none of the above
A) 4 moles of oxygen.
37) How many moles of carbon are in 3.5 moles of calcium carbonate?
A) 10.5
B) 3.5
C) 7
D) 100.09
E) none of the above
B) 3.5
38) How many moles of fluorine are in 3.2 moles of xenon hexafluoride?
A) 22.4
B) 12.8
C) 19.2
D) 16
E) none of the above
C) 19.2
39) If a sample of carbon dioxide contains 3.8 moles of oxygen atoms, how many moles of
carbon dioxide are in the sample?
A) 1.9
B) 3.8
C) 7.6
D) 11.4
E) none of the above
A) 1.9
40) A 15.5 gram sample of diphosphorous pentoxide contains how many grams of phosphorous?
A) 3.38
B) 1.69
C) 6.76
D) 13.5
E) none of the above
C) 6.76
41) A 42.7 gram sample of potassium nitrate contains how many grams of potassium?
A) 39.1
B) 16.5
C) 21.4
D) 8.54
E) none of the above
B) 16.5
42) An iron ore sample is found to be 35.00% Fe by mass. How many grams of ore are needed to
obtain 454.0 grams of Fe?
A) 1297
B) 158.9
C) 295.1
D) 350.0
E) none of the above
A) 1297
43) A 500. gram iron ore sample was determined to contain 242 grams of iron. What is the mass
percent of iron in the ore?
A) 93.7
B) 48.4
C) 51.6
D) 32.6
E) none of the above
B) 48.4
44) Bauxite is an ore that contains the element aluminum. If you obtained 108 grams of
aluminum from an ore sample that initially weighed 204 grams, what is the mass percent of
aluminum in this bauxite ore?
A) 52.9
B) 15.6
C) 0.53
D) 47.1
E) none of the above
A) 52.9
45) What is the mass percent of hydrogen in water?
A) 33.3
B) 88.8
C) 5.60
D) 11.2
E) none of the above
D) 11.2
46) What is the mass percent of chlorine in hydrochloric acid?
A) 2.8
B) 35.5
C) 97.2
D) 70.1
E) none of the above
C) 97.2
47) What is the mass percent of carbon in oxalic acid, H2C2O4?
A) 2.24
B) 13.3
C) 26.7
D) 34.5
E) none of the above
C) 26.7
48) Which of the following compounds has the highest mass percent of “O”?
A) MnO
B) MnO2
C) Mn2O3
D) Mn3O2
E) none of the above
B) MnO2
49) Which of the following statements about empirical formulas is incorrect?
A) An empirical formula represents a molecule.
B) An empirical formula gives the smallest whole number ratio of each type of atom in a
molecule.
C) An empirical formula must be multiplied by an integer to obtain the molecular formula.
D) The molecular formula can be the same as the empirical formula in some situations.
E) All statements are correct.
A) An empirical formula represents a molecule.
50) The empirical formula of a compound:
A) describes the mass relationships in a molecule.
B) is the same as the molecular formula.
C) indicates the structure of the molecule.
D) indicates the simplest ratio of atoms in the compound.
E) none of the above
D) indicates the simplest ratio of atoms in the compound.
51) The simplest formula for hydrogen peroxide is HO. To determine its molecular formula, it is
necessary to know:
A) the properties of hydrogen peroxide.
B) the density of hydrogen peroxide.
C) the molar mass of hydrogen peroxide.
D) the number of moles of hydrogen peroxide in 1.00 g of the substance.
E) none of the above
C) the molar mass of hydrogen peroxide.
52) Which of the following is already in its empirical formula?
A) C22H34O10
B) C6H6
C) c6h12o3-structure/”>c6h12o3
D) C5H12O2
E) none of the above
D) C5H12O2
53) The chemical formula CH2O can be classified as:
A) molecular only.
B) empirical only.
C) empirical, possibly molecular.
D) not enough information
E) none of the above
C) empirical, possibly molecular.
54) A chromium oxide compound contains 104.0 grams of chromium and 48.0 grams of oxygen.
What is the most likely empirical formula of this compound?
A) CrO
B) CrO2
C) CrO3
D) Cr2O3
E) Cr3O2
D) Cr2O3
55) An iron chloride compound contains 55.85 grams of iron and 106.5 grams of chlorine. What
is the most likely empirical formula for this compound?
A) FeCl
B) FeCl2
C) Fe2Cl
D) FeCl3
E) Fe3Cl
D) FeCl3
56) A 7.96 gram sample of silver reacts with oxygen to form 8.55 gram of the metal oxide. What
is the formula of the oxide?
A) AgO
B) AgO2
C) Ag2O
D) Ag3O
E) none of the above
C) Ag2O
57) Determine the empirical formula of a compound containing 60.3% magnesium and 39.7%
oxygen.
A) MgO
B) MgO2
C) Mg2O3
D) Mg2O
E) none of the above
A) MgO
58) Determine the empirical formula of a compound containing 83% potassium and 17.0%
oxygen.
A) KO
B) KO2
C) K2O3
D) K2O
E) none of the above
D) K2O
59) Vitamin C is known chemically by the name ascorbic acid. Determine the empirical formula
of ascorbic acid if it is composed of 40.92% carbon, 4.58% hydrogen, and 54.50% oxygen.
A) CHO
B) CH2O
C) C2H3O2
D) c3h4o3
E) none of the above
D) C3H4O3
60) Determine the correct empirical formula of a compound containing 26.68% carbon, 2.24%
hydrogen, and 71.08% oxygen.
A) CHO
B) CHO2
C) C0.5H0.5O1
D) c2h2o4
E) none of the above
B) CHO2
61) A compound composed of only carbon and hydrogen is 25.2% hydrogen by mass. The
empirical formula for this compound is:
A) CH 0.25
B) C3H
C) CH4
D) C2H8
E) none of the above
C) CH4
62) What is the molecular formula of a compound given the molar mass of the compound is 186.5 gram and the empirical formula is C2H7?
A) C4H14
B) C3H21
C) C2H7
D) C2H14
E) none of the above
E) none of the above
63) An estrogen compound with the empirical formula C12H17O2 has a molecular mass of
386.6 g/mol. What is the value of n necessary to find the molecular formula?
A) 0.2
B) 1
C) 2
D) 20
E) none of the above
C) 2
64) What is the value of n when the empirical formula is C3H5 and the molecular mass is 205.4 g/mol?
A) 0.02
B) 5
C) 10
D) 140
E) none of the above
B) 5
65) What would the empirical formula be for the molecular compound c6h9O4?
A) C2H3O2
B) CH3O2
C) C3H6O2
D) C3H9O4
E) none of the above
E) none of the above
66) What is the molecular formula of a compound given the molar mass of the compound is
30.04 gram and the empirical formula is NH?
A) NH
B) N2H2
C) N2H6
D) N4H4
E) none of the above
B) N2H2
67) A compound has a molar mass of 180.18 g/mol. Given the following percent composition,
calculate the molecular formula: 39.99% C, 6.73% H, 53.28% O.
A) CH3O2
B) CH2O
C) C3H6O3
D) C6H12O6
E) none of the above
D) C6H12O6
68) An unknown acid has a molar mass of 60.06 g/mol. Given the following percent composition, what is the molecular formula? 40% C, 6.7% H, 53.3% O .
A) C3H4O3
B) CH2O
C) C2H4O2
D) C6H12O6
E) none of the above
C) C2H4O2
69) A compound composed of only hydrogen and oxygen is 5.94% hydrogen by mass. The
molar mass of this compound is 34.02 g/mol. What is the compound’s molecular formula?
A) 34.02
B) H2O2
C) HO
D) H6O
E) none of the above
B) H2O2
1) Bananas cost 33¢ per pound. If you spent $0.77, how many pounds of bananas did you
purchase?
A) 2.33
B) 1.73
C) 0.429
D) 2.01
E) none of the above
A) 2.33
2) How many atoms are present in 4.5 moles?
A) 3.7 x 1023
B) 3.7 x 10-25
C) 2.7 x 1024
D) 6.02 x 1023
E) none of the above
C) 2.7 x 1024
3) If you have 2.41 x 1024 atoms of copper, how many moles of copper do you have?
A) 0.250
B) 4.00
C) 0.600
D) 3.00
E) none of the above
B) 4.00
4) How many moles of potassium are in 156.4 g?
A) 39.10
B) 4.000
C) 0.2500
D) 5.050
E) none of the above
B) 4.000
5) What is the mass of 3.91 x 1024 sulfur atoms?
A) 208
B) 4.93
C) 155
D) 32.07
E) none of the above
A) 208
6) How many atoms of lithium are in 18.7 g?
A) 2.14 x 1024
B) 2.70 x 1024
C) 1.62 x 1024
D) 3.11 x 1024
E) none of the above
C) 1.62 x 1024
7) What is the mass (in grams) of 1.95 moles of water ?
A) 18.02
B) 9.24
C) 35.1
D) 6.022 × 10 23
E) none of the above
C) 35.1
8) What is the mass (in grams) of 3.03 × 1024 molecules of carbon dioxide molecules?
A) 221
B) 0.114
C) 1.33
D) 44.01
E) none of the above
A) 221
9) How many moles of oxygen are in 3.30 moles of NaClO4 ?
A) 3.30
B) 0.303
C) 19.0
D) 13.2
E) none of the above
D) 13.2
10) Given that sodium chloride is 39.0% sodium by mass, how many grams of sodium chloride
are needed to have 950 mg of Na present?
A) 2.44
B) 0.371
C) 2,430
D) 37.1
E) none of the above
A) 2.44
11) What is the mass percent of Na in sodium chloride?
A) 58.4
B) 60.7
C) 39.3
D) 47.5
E) none of the above
C) 39.3
12) What is the mass percent of oxygen in sodium oxide?
A) 37.1
B) 25.8
C) 74.2
D) 62.0
E) none of the above
B) 25.8