Deck 3: Mass Relationships in Chemical Reactions

Question 1

An atom of helium has a mass about four times greater than that of an atom of hydrogen. Which choice makes the correct comparison of the redative numbers of helium and hydrogen atoms in equal masses of the two elements

A) There are about four times as many helium atoms as hydrogen atoms.
B) There are about two times as many helium atoms as hydrogen atoms.
C) The number of helium and hydrogen atoms is the same.
D) There are about half as many helium atoms as hydrogen atoms.
E) There are about one-fourth as many helium atoms as hydrogen atoms.

Answer 1

There are about one-fourth as many helium atoms as hydrogen atoms.

Question 2

Calculate the average atomic mass of lithium using the following data: $\begin{array}{|l|l|l|}\hline \text { Isotope } & \text { Abundance } & \text { Mass } \\\hline ^{6} \mathrm{Li} & 7.5 \% & 6.0151~ \mathrm{amu} \\\hline ^7 \mathrm{Li} & 92.5 \% & 7.0160 ~\mathrm{aum} \\\hline\end{array}$

A) 6.51 amu
B) 6.02 amu
C) 6.94 amu
D) 7.02 amu
E) 6.50 amu

Answer 2

6.94 amu

Question 3

What is the molecular mass of Br₂

A) 79.90 amu
B) 79.90 g
C) 159.8 amu
D) 159.8 g
E) 2.65 x 10^-22 amu

Answer 3

159.8 amu

Question 4

There are two stable isotopes of chlorine: chlorine-35, with a mass of 34.968853 amu; and chlorine-37, with a mass of 36.965903. Given that the average atomic mass of a chlorine atom is 35.45 amu, which of the following statements is true?

A) Chlorine contains almost exclusively $~{}_{17}^{35}\text{Cl}$ with very little $~{}_{17}^{35}\text{Cl}$
B) Chlorine contains more $~{}_{17}^{35}\text{Cl}$ than $~{}_{17}^{35}\text{Cl}$ .
C) Chlorine contains roughly equal amounts of $~{}_{17}^{35}\text{Cl}$ and $~{}_{17}^{35}\text{Cl}$
D) Chlorine contains more $~{}_{17}^{35}\text{Cl}$ than $~{}_{17}^{35}\text{Cl}$
E) Chlorine contains almost exclusively of $~{}_{17}^{35}\text{Cl}$ , with very little $~{}_{17}^{35}\text{Cl}$ .

Question 5

The element oxygen consists of three naturally occurring isotopes: ¹⁶O, ¹⁷O, and ¹⁸O. The atomic mass of oxygen is 16.0 amu. What can be implied about the relative abundances of these isotopes

A) More than 50% of all O atoms are ¹⁷O.
B) Almost all O atoms are ¹⁸O.
C) Almost all O atoms are ¹⁷O.
D) The isotopes all have the same abundance, i.e. 33.3%.
E) The abundances of ¹⁷O and ¹⁸O are very small.

Question 6

What is the average mass of one S atom

A) 32.07 g
B) 32.07 amu
C) 32.07 g/mol
D) 5.32 x 10^-23 amu
E) 1.93 x 10²⁵ g

Question 7

Boron obtained from borax deposits in Death Valley consists of two isotopes. They are boron-10 and boron-11 with atomic masses of 10.013 amu and 11.009 amu, respectively. The atomic mass of boron is 10.81 amu (see periodic table). Which isotope of boron is more abundant, boron-10 or boron-11

A) Cannot be determined from data given
B) Neither, their abundances are the same.
C) Boron-10
D) Boron-11

Question 8

What is the mass of 3.50 x 10²⁴ Ti atoms

A) 47.9 amu
B) 47.9 g
C) 5.81 g
D) 278 g
E) 5.81 amu

Question 9

If 0.274 moles of a substance weighs 62.5 g, what is the molar mass of the substance, in units of g/mol

A) 2.28 * 10² g/mol
B) 1.71 * 10¹ g/mol
C) 4.38 * 10^-3 g/mol
D) 2.17 * 10² g/mol
E) 6.02 * 10²³ g/mol

Question 10

How many Br atoms are in 2.50 g of Br

A)1.88 x 10²² Br atoms
B) 1.51 x 10²⁴ Br atoms
C) 7.54 x 10²¹ Br atoms
D) 6.02 x 10²³ Br atoms
E) 9.42 x 10²¹ Br atoms

Question 11

One mole of iron

A) is heavier than one mole of lead (Pb).
B) is 77.0 g of iron.
C) is 26.0 g of iron.
D) weighs the same as one mole of lead.
E) None of the above.

Question 12

An atom of bromine has a mass about four times greater than that of an atom of neon. Which choice makes the correct comparison of the relative numbers of bromine and neon atoms in 1,000 g of each element

A) The number of bromine and neon atoms is the same.
B) There are one thousand times as many bromine atoms as neon atoms.
C) There are one thousand times as many neon atoms as bromine atoms.
D) There are four times as many neon atoms as bromine atoms.
E) There are four times as many bromine atoms as neon atoms.

Question 13

An average atom of uranium (U) is approximately how many times heavier than an atom of potassium

A) 6.1 times
B) 4.8 times
C) 2.4 times
D) 12.5 times
E) 7.7 times

Question 14

Calculate the average atomic mass of silver using the following data:

$\begin{array}{|l|l|l|}\hline \text { Isotope } & \text { Abundance } & \text { Mass } \\\hline ^{107} \mathrm{Ag} & 51.84 \% & 106.9051 ~\mathrm{amu} \\\hline ^{109} \mathrm{Ag} & 48.16 \% & 108.9048 ~\mathrm{amu} \\\hline\end{array}$

A) 106.91 amu
B) 108.00 amu
C) 107.90 amu
D) 107.87 amu
E) 108.90 amu

Question 15

An atom of bromine has a mass about four times greater than that of an atom of neon. How many grams of neon will contain the same number of atoms as 1,000 g of bromine

A) 4 g Ne
B) 250 g Ne
C) 400 g Ne
D) 1,000 g Ne
E) 4,000 g Ne

Question 16

What is the mass of 4.50 x 10²² Cu atoms

A) 7.47 x 10^-2 g
B) 7.47 x 10^-2 amu
C) 4.75 g
D) 63.55 amu
E) 63.55 g

Question 17

What is the average mass, in grams, of one Zn atom

A) 65.39 amu
B) 65.39 g
C) 3.94 x 10²⁵g
D) 1.09 x 10^-22 g
E) 1.661 x 10^-24g

Question 18

Which one of the following does not represent 1.000 mol of the indicated substance

A) 6.022 * 10²³ C atoms
B) 26.00 g Fe
C) 12.01 g C
D) 65.39 g Zn
E) 6.022 * 10²³ Fe atoms

Question 19

What is the average mass, in grams, of one Rb atom

A) 6.02 x 10²³ g
B) 1.42 x 10^-22g
C) 5.15 x 10²⁵ g
D) 85.47 g
E) 85.47 amu

Question 20

What is the average mass of one Ca atom

A) 40.08 amu
B) 40.08 g
C) 40.08 g/mol
D) 2.41 x 10^-21 amu
E) 2.41x10²⁵ g

Question 21

How many F atoms are in 5.54 g of F₂

A) 6.02 * 10²³ atoms
B) 0.146 atoms
C) 0.292 atoms
D) 8.78 * 10²² atoms
E) 1.76 * 10²³ atoms

Question 22

How many C atoms are in 5.50 g of C

A) 5.01 x 10²² C atoms
B) 3.31 x 10²⁴ C atoms
C) 6.02 x 10²³ C atoms
D) 2.76 x 10²³ C atoms
E) 5.50 x 10²³ C atoms

Question 23

Which of the following NH₃ samples contains the greatest number of moles of NH₃

A) 0.356 moles NH₃
B) 4.65 x 10²³ NH₃ molecules
C) 6.78 x 10²² NH₃ molecules
D) 8.90g NH₃
E) 6.78 x 10¹g NH₃

Question 24

How many moles of CF₄ are there in 171 g of CF₄

A) 0.51 mol
B) 1.94 mol
C) 4.07 mol
D) 88.0 mol
E) 171 mol

Question 25

A copper wire has a diameter of 2.00 mm. What length of this wire contains exactly 1.00 mol of copper (density of Cu = 8.92 g/cm³)

A) 0.178 m
B) 0.567 m
C) 180 m
D) 45.1 m
E) 2.27 m

Question 26

Calculate the molar mass of (NH₄)₂SO₄.

A) 114.11 g/mol
B) 228.22 g/mol
C) 118.14 g/mol
D) 63.09 g/mol
E) 132.15 g/mol

Question 27

Which of the following CO₂ samples contains the greatest number of moles of CO₂

A) 3.5 moles CO₂
B) 3.21 x 10²³ CO₂ molecules
C) 4.50 x 10²² CO₂ molecules
D) 5.60 g CO₂
E) 3.19 x 10¹ g CO₂

Question 28

How many moles of NH₃ are there in 77.5 g of NH₃

A) 0.220 mol
B) 4.55 mol
C) 14.0 mol
D) 1.31 * 10³ mol
E) None of the above.

Question 29

How many O atoms are in 4.39 g of CO₂

A) 5.29 x 10²⁴ O atoms
B) 1.03 x 10²² O atoms
C) 1.65 x 10²³ O atoms
D) 6.01 x 10²² O atoms
E) 1.20 x 10²³ O atoms

Question 30

Calculate the molar mass of Ba(NO₃)₂.

A) 199.3 g/mol
B) 323.3 g/mol
C) 247.3 g/mol
D) 261.3 g/mol
E) 398.6 g/mol

Question 31

A silver wire has a diameter of 0.500 mm. What length of this wire contains exactly 1.00 mol of silver (density of Ag = 10.5 g/cm³)

A) 52.3 m
B) 222 m
C) 13.1 m
D) 2.01 m
E) 890 m

Question 32

What is the molar mass of acetaminophen, C₈H₉NO₂

A) 151.16 g/mol
B) 43.03 g/mol
C) 67.09 g/mol
D) 143.10 g/mol
E) 135.16 g/mol

Question 33

Calculate the number of moles of cesium in 50.0 g of cesium.

A) 0.376 mol
B) 0.357 mol
C) 2.66 mol
D) 2.80 mol
E) 0.0200 mol

Question 34

What is the molecular mass of nicotine, C₁₀H₁₄N₂

A) 27.03 amu
B) 148.22 amu
C) 149.13 amu
D) 81.12 amu
E) 162.23 amu

Question 35

Which of the following samples contains the greatest number of atoms

A) 100 g of Pb
B) 2.0 mole of Ar
C) 0.1 mole of Fe
D) 5 g of He
E) 20 million O₂ molecules

Question 36

How many Cl atoms are in 0.0728 g of PCl₃

A) 4.38 x 10²² Cl atoms
B) 1.32 x 10²³ Cl atoms
C) 3.19 x 10²⁰ Cl atoms
D) 9.58 x 10²⁰ Cl atoms
E) 1.81 x 10²⁴ Cl atoms

Question 37

Determine the number of moles of aluminum in 96.7 g of Al.

A) 0.279 mol
B) 3.58 mol
C) 7.43 mol
D) 4.21 mol
E) 6.02 * 10²³ mol

Question 38

Calculate the number of moles of xenon in 12.0 g of xenon.

A) 1.00 mol
B) 0.0457 mol
C) 0.183 mol
D) 7.62 * 10^-3 mol
E) 0.0914 mol

Question 39

A gold wire has a diameter of 1.00 mm. What length of this wire contains exactly 1.00 mol of gold (density of Au = 17.0 g/cm³)

A) 2630 m
B) 3.69 m
C) 251 m
D) 14.8 m
E) 62.7 m

Question 40

Calculate the molecular mass of menthol, C₁₀H₂₀O.

A) 156.26 amu
B) 140.26 amu
C) 29.02 amu
D) 48.17 amu
E) 137.11 amu

Question 41

Calculate the mass of O in 4.36 g of Cl₂O₇

A) 30.5 g O
B) 48.8 g O
C) 11.2 g O
D) 69.8 g O
E) 2.67 g O

Question 42

How many moles of C are in 1.22 moles of C₆H₁₂O₆

A) 7.32 moles C
B) 87.9 moles C
C) 1.22 moles C
D) 14.7 moles C
E) 2.44 moles C

Question 43

Calculate the mass of 0.00456 moles of (NH₄)₂SO₄.

A) 132 g
B) 3.45 x 10^-5 g
C) 114 g
D) 0.603 g
E) 0.520 g

Question 44

How many fluorine atoms are there in 65 g of CF₄

A) 0.74 atoms
B) 3.0 atoms
C) 4.5 * 10²³ atoms
D) 1.8 * 10²⁴ atoms
E) 2.4 * 10²³ atoms

Question 45

How many moles of HCl are represented by 1.0 * 10¹⁹ HCl molecules

A) 1.7 * 10^-5 mol
B) 1.5 * 10^-3 mol
C) 1.0 * 10¹⁹ mol
D) 37 mol
E) 6.0 * 10⁴ mol

Question 46

Calculate the mass of 3.00 moles of CF₂Cl₂.

A) 3.00 g
B) 174 g
C) 363 g
D) 1.81 * 10²⁴ g
E) 40.3 g

Question 47

How many sodium atoms are there in 6.0 g of Na₃N

A) 3.6 * 10²⁴ atoms
B) 4.6 * 10²² atoms
C) 1.3 * 10²³ atoms
D) 0.22 atoms
E) 0.072 atoms

Question 48

How many moles of O are in 2.45 moles of H₂CO₃

A) 2.45 moles O
B) 39.2 moles O
C) 118 moles O
D) 7.35 moles O
E) 0.459 moles O

Question 49

How many carbon atoms are there in 15 lbs of sugar, C₁₂H₂₂O₁₁

A) 4.1 x 10²⁸ C atoms
B) 1.2 x 10²⁶ C atoms
C) 1.4 x 10²⁶ C atoms
D) 2.6 x 10²² C atoms
E) 3.2 x 10²³ C atoms

Question 50

Calculate the mass of 4.50 moles of Ca₃PO₄.

A) 215 g
B) 968 g
C) 0.0209 g
D) 87.1 g
E) 392 g

Question 51

Formaldehyde has the formula CH₂O. How many molecules are there in 0.11 g of formaldehyde

A) 6.1 * 10^-27
B) 3.7 * 10^-3
C) 4.0
D) 2.2 * 10²¹
E) 6.6 * 10²²

Question 52

How many O atoms are there in 51.4 g CaSO₄

A) 4.00
B) 2.40 * 10²⁴
C) 1.13
D) 9.09 * 10²³
E) 2.28 * 10²³

Question 53

How many sulfur atoms are there in 21.0 g of Al₂S₃

A) 8.42 * 10²² atoms
B) 2.53 * 10²³ atoms
C) 2.14 * 10²³ atoms
D) 6.02 * 10²³ atoms
E) 6.30 * 10²⁶ atoms

Question 54

How many sulfur atoms are present in 25.6 g of Al₂(S₂O₃)₃

A) 0.393
B) 6.00
C) 3.95 * 10²²
D) 7.90 * 10²²
E) 2.37 * 10²³

Question 55

How many moles of O atoms are in 25.7 g of CaSO₄

A) 0.189 mol
B) 0.755 mol
C) 4.00 mol
D) 1.14 * 10²³ mol
E) 4.55 * 10²³ mol

Question 56

The molecular formula of aspirin is C₉H₈O₄. How many aspirin molecules are present in one 500-milligram tablet

A) 2.77 molecules
B) 2.77 * 10^-3 molecules
C) 1.67 * 10²⁴ molecules
D) 1.67 * 10²¹ molecules
E) None of these is correct.

Question 57

How many molecules are there in 8.0 g of ozone, O₃

A) 3.0 molecules
B) 3.6 * 10²⁴ molecules
C) 1.0 * 10²³ molecules
D) 3.0 * 10²³ molecules
E) 6.0 * 10²³ molecules

Question 58

What is the mass of 0.0250 mol of P₂O₅

A) 35.5 g
B) 5676 g
C) 0.0250 g
D) 1.51 * 10²² g
E) 3.55 g

Question 59

How many moles of Cl atoms are there in 65.2 g CHCl₃

A) 0.548 mol
B) 1.09 mol
C) 3.30 * 10²³ mol
D) 1.64 mol
E) 3.00 mol

Question 60

How many moles of H are in 4.56 moles of NH₂NH₂

A) 4.52 moles H
B) 4.56 moles H
C) 9.12 moles H
D) 18.39 moles H
E) 18.24 moles H

Question 61

A compound with an empirical formula of C₂H₄Br has a molar mass of 215.90 g/mol. What is the molecular formula

A) C₄H₈Br₂
B) C₂H₄Br
C) CHBr
D) C₆H₁₂Br₃
E) C₄H₈Br

Question 62

Zircon is a mineral with the empirical formula ZrSiO₄. If all the zirconium is ⁹⁰Zr, all the silicon is ²⁸Si, and all the oxygen is ¹⁶O, what mass of oxygen is present in 10. g of zircon

A) 0.88 g
B) 1.2 g
C) 1.8 g
D) 3.5 g
E) 5.4 g

Question 63

The mineral pyrolusite is a compound of ⁵⁵Mn and ¹⁶O. If 63% of the mass of pyrolusite is due to manganese, what is the empirical formula of pyrolusite

A) MnO
B) Mn₂O
C) Mn₂O₂
D) MnO₂
E) none of these

Question 64

Calculate the mass of N in 2.34 g of N₂H₄

A) 4.68 g N
B) 65.6 g N
C) 28.02 g N
D) 2.05 g N
E) 2.34 g N

Question 65

A compound with an empirical formula of C₂H₃Br₂ has a molar mass of 373.69 g/mol. What is the molecular formula

A) C₂H₃Br₂
B) CHBr
C) C₆H₉Br₆
D) C₄H₆Br₂
E) C₄H₆Br₄

Question 66

The mineral hausmannite is a compound of ⁵⁵Mn and ¹⁶O. If 72% of the mass of hausmannite is due to manganese, what is the empirical formula of hausmannite

A) MnO
B) Mn₃O
C) Mn₃O₄
D) Mn₄O₃
E) MnO₃

Question 67

The percent composition by mass of a compound is 76.0% C, 12.8% H, and 11.2% O. The molar mass of this compound is 284.5 g/mol. What is the molecular formula of the compound

A) C₁₀H₆O
B) C₉H₁₈O
C) C₁₆H₂₈O₄
D) C₂₀H₁₂O₂
E) C₁₈H₃₆O₂

Question 68

The mineral orpiment, having the empirical formula As₂S₃, was used in ancient times as a cosmetic. What mass of arsenic is present in 5.0 g of orpiment [Given: naturally occurring arsenic is all arsenic-75; assume that all naturally occurring sulfur is sulfur-32 (only approximately true)]

A) 0.61 g
B) 3.0 g
C) 1.5 g
D) 2.0 g
E) 3.5 g

Question 69

A mass spectrometer works by ionizing atoms or molecules, and then accelerating them through oppositely charged plates. The mass is obtained by

A) measuring the force of impact on a detecting screen, and then calculating the mass using force = mass * acceleration.
B) suspending the ions in an applied electric field, and then calculating mass by the setting the downward gravitational force equal to the upward electrostatic force.
C) measuring the magnitude of deflection as the ions pass through a magnetic field to obtain the charge-to-mass ratio, and then calculating the mass from that ratio.
D) measuring the time it takes for the ions to hit the detector at a known distance to calculate the acceleration, and then calculating mass from force = mass * acceleration.

Question 70

What is the mass of 0.55 mole of C₆H₆

A) 78.11 g
B) 78.11 amu
C) 42.96 g
D) 42.96 amu
E) 7.04 x 10^-3 g

Question 71

Calculate the mass of C in 5.46 g of C₂H₄

A) 0.455 g C
B) 4.68 g C
C) 65.6 g C
D) 13.1 g C
E) 24.0 g C

Question 72

What is the mass of 3.00 moles of ethanol, C₂H₆O

A) 4.99 * 10^-24 g
B) 138 g
C) 6.52 * 10^-2 g
D) 50.0 g
E) 1.81 * 10²⁴ g

Question 73

The mineral manganosite is a compound of ⁵⁵Mn and ¹⁶O. If 77% of the mass of manganosite is due to manganese, what is the empirical formula of manganosite

A) MnO
B) Mn₂O
C) Mn₂O₂
D) MnO₂
E) none of these

Question 74

An unknown compound with a molar mass of 155.06 g/mol consists of 46.47% C, 7.80% H, and 45.72% Cl. Find the molecular formula for the compound.

A) CHCl
B) C₉H₁₈Cl₃
C) C₆H₁₂Cl
D) C₆H₁₂Cl₂
E) C₃H₆Cl

Question 75

Calculate the mass of 4.50 moles of chlorine gas, Cl₂.

A) 6.34 * 10^-2 g
B) 4.50 g
C) 15.7 g
D) 160. g
E) 319 g

Question 76

An unknown compound with a molar mass of 223.94 g/mol consists of 32.18% C, 4.50% H, and 63.32% Cl. Find the molecular formula for the compound.

A) CHCl
B) C₆H₁₀Cl₄
C) C₃H₅Cl₂
D) C₉H₁₅Cl₆
E) C₆H₁₀Cl₂

Question 77

The empirical formula of a compound of uranium and fluorine that is composed of 67.6% uranium and 32.4% fluorine is

A) U₂F.
B) U₃F₄.
C) UF₄.
D) UF₆.
E) UF₈.

Question 78

A compound with an empirical formula of C₂H₂Br₃ has a molar mass of 531.47 g/mol. What is the molecular formula

A) C₂H₂Br₃
B) C₄H₄Br₆
C) CHBr
D) C₄H₄Br₃
E) C₆H₆Br₉

Question 79

How many grams of nitrogen are there in 7.5 g of Ca(NO₃)₂

A) 0.64 g
B) 1.3 g
C) 0.15 g
D) 1.2 g
E) 2.3 g

Question 80

What is the mass of 8.25 * 10¹⁹ UF₆ molecules

A) 352 g
B) 0.0482 g
C) 1.37 * 10^-4 g
D) 2.90 * 10²² g
E) 8.25 * 10¹⁹ g