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Chapter 1

Atoms

Educators

ES

Problem 1

Explain this statement in your own words and give an example.
The properties of the substances around us depend on the structure of the particles that compose them.

A. Elizabeth H.
Numerade Educator

Problem 2

Explain the main goal of chemistry.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 3

What are two different ways to classify matter?

A. Elizabeth H.
Numerade Educator

Problem 4

How do solids, liquids, and gases differ?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 5

Explain the difference between a pure substance and a mixture based on the composite particles of each.

A. Elizabeth H.
Numerade Educator

Problem 6

Explain the difference between an element and a compound.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 7

Explain the difference between a homogeneous and a heterogeneous mixture.

A. Elizabeth H.
Numerade Educator

Problem 8

Describe the scientific approach to knowledge. How does it differ from other approaches?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 9

Explain the differences between a hypothesis, a law, and a theory.

A. Elizabeth H.
Numerade Educator

Problem 10

What observations did Antoine Lavoisier make? What law did he formulate?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 11

What theory did John Dalton formulate?

A. Elizabeth H.
Numerade Educator

Problem 12

What is wrong with the expression, 'That is just a theory,' if by theory the speaker is referring to a scientific theory?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 13

Summarize the history of the atomic idea. How was Dalton able to convince others to accept an idea that had been controversial for 2000 years?

A. Elizabeth H.
Numerade Educator

Problem 14

State and explain the law of conservation of mass.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 15

State and explain the law of definite proportions.

A. Elizabeth H.
Numerade Educator

Problem 16

State and explain the law of multiple proportions. How is the law of multiple proportions different from the law of definite proportions?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 17

What are the main ideas in Dalton"s atomic theory? How do they help explain the laws of conservation of mass, of constant composition, and of definite proportions?

A. Elizabeth H.
Numerade Educator

Problem 18

How and by whom was the electron discovered? What basic properties of the electron were reported with its discovery?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 19

Explain Millikan"s oil drop experiment and how it led to the measurement of the electron"s charge. Why is the magnitude of the charge of the electron so important?

A. Elizabeth H.
Numerade Educator

Problem 20

Describe the plum-pudding model of the atom.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 21

Describe Rutherford"s gold foil experiment. How did the experiment prove that the plum-pudding model of the atom was wrong?

A. Elizabeth H.
Numerade Educator

Problem 22

Describe Rutherford"s nuclear model of the atom. What was revolutionary about his model?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 23

If matter is mostly empty space, as suggested by Rutherford, then why does it appear so solid?

A. Elizabeth H.
Numerade Educator

Problem 24

List the three subatomic particles that compose atoms and give the basic properties (mass and charge) of each.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 25

What defines an element?

A. Elizabeth H.
Numerade Educator

Problem 26

Explain the difference between Z (the atomic number) and A (the mass number).

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 27

Where do elements get their names?

A. Elizabeth H.
Numerade Educator

Problem 28

What are isotopes? What is percent natural abundance of isotopes?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 29

Describe the two different notations used to specify isotopes and give an example of each.

A. Elizabeth H.
Numerade Educator

Problem 30

What is an ion? A cation? An anion?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 31

What is atomic mass? How is it calculated?

A. Elizabeth H.
Numerade Educator

Problem 32

Explain how a mass spectrometer works. What kind of information can be determined from a mass spectrum?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 33

What is a mole? How is the mole concept useful in chemical calculations?

A. Elizabeth H.
Numerade Educator

Problem 34

Why is the mass corresponding to a mole of one element different from the mass corresponding to a mole of another element?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 35

Each shape represents a type of particle (such as an atom or a molecule). Classify each image as a pure substance, homogeneous mixture, or heterogeneous mixture.

A. Elizabeth H.
Numerade Educator

Problem 36

Using triangles to represent one type of atom and circles to represent another type of atom, draw one image to represent a mixture of the two atoms and draw another image to represent a compound composed of the two atoms.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 37

Classify each substance as a pure substance or a mixture. If it is a pure substance, classify it as an element or a compound. If it is a mixture, classify it as homogeneous or heterogeneous.

a. sweat
b. carbon dioxide
c. aluminum
d. vegetable soup

Ernest W.
Numerade Educator

Problem 38

Classify each substance as a pure substance or a mixture. If it is a pure substance, classify it as an element or a compound. If it is a mixture, classify it as homogeneous or heterogeneous.

a. wine
b. beef stew
c. iron
d. carbon monoxide

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 39

Complete the table.

A. Elizabeth H.
Numerade Educator

Problem 40

Complete the table.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 41

Determine whether each molecular diagram represents a pure substance or a mixture. If it represents a pure substance, classify the substance as an element or a compound. If it represents a mixture, classify the mixture as homogeneous or heterogeneous.

Charotte M.
Numerade Educator

Problem 42

Determine whether each molecular diagram represents a pure substance or a mixture. If it represents a pure substance, classify the substance as an element or a compound. If it represents a mixture, classify the mixture as homogeneous or heterogeneous.

David C.
Numerade Educator

Problem 43

Classify each statement as an observation, a law, or a theory.

a. All matter is made of tiny, indestructible particles called atoms.
b. When iron rusts in a closed container, the mass of the container and its contents do not change.
c. In chemical reactions, matter is neither created nor destroyed.
d. When a match burns, heat is released.

A. Elizabeth H.
Numerade Educator

Problem 44

Classify each statement as an observation, a law, or a theory.

a. Chlorine is a highly reactive gas.
b. If elements are listed in order of increasing mass of their atoms, their chemical reactivity follows a repeating pattern.
c. Neon is an inert (or nonreactive) gas.
d. The reactivity of elements depends on the arrangement of their electrons.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 45

A chemist decomposes several samples of carbon monoxide into carbon and oxygen and weighs the resulting elements. The results are shown in the table.

a. Describe any pattern you notice in these results. Next, the chemist decomposes several samples of hydrogen peroxide into hydrogen and oxygen. The results are shown in the table.
b. Describe any similarity you notice between these results and those for carbon monoxide in part a.
c. Can you formulate a law from the observations in a and b?
d. Can you formulate a hypothesis that might explain your law in c?

A. Elizabeth H.
Numerade Educator

Problem 46

When astronomers observe distant galaxies, they can tell that most of them are moving away from one another. In addition, the more distant the galaxies, the more rapidly they are likely to be moving away from each other. Can you devise an hypothesis to explain these observations?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 47

A hydrogen-filled balloon is ignited and 1.50 g of hydrogen reacts with 12.0 g of oxygen. How many grams of water vapor form? (Assume that water vapor is the only product.)

Ernest W.
Numerade Educator

Problem 48

An automobile gasoline tank holds 21 kg of gasoline. When the gasoline burns, 84 kg of oxygen is consumed, and carbon dioxide and water are produced. What is the total combined mass of carbon dioxide and water that is produced?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 49

Two samples of carbon tetrachloride are decomposed into their constituent elements. One sample produces 38.9 g of carbon and 448 g of chlorine, and the other sample produces 14.8 g of carbon
and 134 g of chlorine. Are these results consistent with the law of definite proportions? Show why or why not.

Ernest W.
Numerade Educator

Problem 50

Two samples of sodium chloride are decomposed into their constituent elements. One sample produces 6.98 g of sodium and 10.7 g of chlorine, and the other sample produces 11.2 g of sodium and 17.3 g of chlorine. Are these results consistent with the law of definite proportions? Explain your answer.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 51

The mass ratio of sodium to fluorine in sodium fluoride is 1.21:1. A sample of sodium fluoride produces 28.8 g of sodium upon decomposition. How much fluorine (in grams) is formed?

Ernest W.
Numerade Educator

Problem 52

Upon decomposition, one sample of magnesium fluoride produces 1.65 kg of magnesium and 2.57 kg of fluorine. A second sample produces 1.32 kg of magnesium. How much fluorine (in grams) does the second sample produce?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 53

Two different compounds containing osmium and oxygen have the following masses of oxygen per gram of osmium: 0.168 and 0.3369 g. Show that these amounts are consistent with the law of multiple proportions.

Ernest W.
Numerade Educator

Problem 54

Palladium forms three different compounds with sulfur. The mass of sulfur per gram of palladium in each compound is listed in the accompanying table.

Show that these masses are consistent with the law of multiple proportions.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 55

Sulfur and oxygen form both sulfur dioxide and sulfur trioxide. When samples of these are decomposed, the sulfur dioxide produces 3.49 g oxygen and 3.50 g sulfur, while the sulfur trioxide produces 6.75 g oxygen and 4.50 g sulfur. Calculate the mass of oxygen per gram of sulfur for each sample and show
that these results are consistent with the law of multiple proportions.

Ernest W.
Numerade Educator

Problem 56

Sulfur and fluorine form several different compounds including sulfur hexafluoride and sulfur tetrafluoride. Decomposition of a sample of sulfur hexafluoride produces 4.45 g of fluorine and 1.25 g of sulfur, while decomposition of a sample of sulfur tetrafluoride produces 4.43 g of fluorine and 1.87 g of sulfur. Calculate the mass of fluorine per gram of sulfur for each sample and show that these results are consistent with the law of multiple proportions.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 57

Which statements are consistent with Dalton"s atomic theory as it was originally stated? Why?

a. Sulfur and oxygen atoms have the same mass.
b. All cobalt atoms are identical.
c. Potassium and chlorine atoms combine in a 1:1 ratio to form potassium chloride.
d. Lead atoms can be converted into gold.

A. Elizabeth H.
Numerade Educator

Problem 58

Which statements are inconsistent with Dalton"s atomic theory as it was originally stated? Why?

a. All carbon atoms are identical.
b. An oxygen atom combines with 1.5 hydrogen atoms to form a water molecule.
c. Two oxygen atoms combine with a carbon atom to form a carbon dioxide molecule.
d. The formation of a compound often involves the destruction of one or more atoms.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 59

Which statements are consistent with Rutherford"s nuclear theory as it was originally stated? Why?

a. The volume of an atom is mostly empty space.
b. The nucleus of an atom is small compared to the size of the atom.
c. Neutral lithium atoms contain more neutrons than protons.
d. Neutral lithium atoms contain more protons than electrons.

A. Elizabeth H.
Numerade Educator

Problem 60

Which statements are inconsistent with Rutherford 's nuclear theory as it was originally stated? Why?

a. Since electrons are smaller than protons, and since a hydrogen atom contains only one proton and one electron, it must follow that the volume of a hydrogen atom is mostly due to the proton.
b. A nitrogen atom has 7 protons in its nucleus and 7 electrons outside of its nucleus.
c. A phosphorus atom has 15 protons in its nucleus and 150 electrons outside of its nucleus.
d. The majority of the mass of a fluorine atom is due to its 9 electrons.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 61

A chemist in an imaginary universe, where electrons have a different charge than they do in our universe, performs the Millikan oil drop experiment to measure the electron"s charge. The charges of several drops are recorded here. What is the charge of the electron in this imaginary universe?

A. Elizabeth H.
Numerade Educator

Problem 62

Imagine a unit of charge called the zorg. A chemist performs the Millikan oil drop experiment and measures the charge of each drop in zorgs. Based on the results shown here, what is the charge of the electron in zorgs (z)? How many electrons are in each drop?

David C.
Numerade Educator

Problem 63

Which statements about subatomic particles are true?

a. If an atom has an equal number of protons and electrons, it will be charge-neutral.
b. Electrons are attracted to protons.
c. Electrons are much lighter than neutrons.
d. Protons have twice the mass of neutrons.

A. Elizabeth H.
Numerade Educator

Problem 64

Which statements about subatomic particles are false?

a. Protons and electrons have charges of the same magnitude but opposite sign.
b. Protons have about the same mass as neutrons.
c. Some atoms don"t have any protons.
d. Protons and neutrons have charges of the same magnitude but opposite signs.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 65

Write isotopic symbols in the form X to A (example C-13) for each isotope.

a. the silver isotope with 60 neutrons
b. the silver isotope with 62 neutrons
c. the uranium isotope with 146 neutrons
d. the hydrogen isotope with 1 neutron

Charotte M.
Numerade Educator

Problem 66

Write isotopic symbols in the form AZ X for each isotope.

a. the copper isotope with 34 neutrons
b. the copper isotope with 36 neutrons
c. the potassium isotope with 21 neutrons
d. the argon isotope with 22 neutrons

David C.
Numerade Educator

Problem 67

Determine the number of protons and the number of neutrons in each isotope.

a. 14
7N
b. 23
11Na
c. 222
86Rn
d. 208
82Pb

Ernest W.
Numerade Educator

Problem 68

Determine the number of protons and the number of neutrons in each isotope.

a. 40
19K
b. 226
88Ra
c. 99
43Tc
d. 33
15P

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 69

The amount of carbon-14 in ancient artifacts and fossils is often used to establish their age. Determine the number of protons and the number of neutrons in a carbon-14 isotope and write its symbol
in the form AZX.

Ernest W.
Numerade Educator

Problem 70

Uranium-235 is used in nuclear fission. Determine the number of protons and the number of neutrons in uranium-235 and write its symbol in the form AZX.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 71

Determine the number of protons and the number of electrons in each ion.

a. Ni2+
b. S2-
c. Br-
d. Cr3+

David C.
Numerade Educator

Problem 72

Determine the number of protons and the number of electrons in each ion.

a. Al3+
b. Se2-
c. Ga3+
d. Sr2+

David C.
Numerade Educator

Problem 73

Gallium has two naturally occurring isotopes with the following masses and natural abundances:

A. Elizabeth H.
Numerade Educator

Problem 74

Magnesium has three naturally occurring isotopes with the following masses and natural abundances:

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 75

The atomic mass of fluorine is 18.998 amu, and its mass spectrum shows a large peak at this mass. The atomic mass of chlorine is 35.45 amu, yet the mass spectrum of chlorine does not show a peak at this mass. Explain the difference.

A. Elizabeth H.
Numerade Educator

Problem 76

The atomic mass of copper is 63.546 amu. Do any copper isotopes have a mass of 63.546 amu? Explain.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 77

An element has two naturally occurring isotopes. Isotope 1 has a mass of 120.9038 amu and a relative abundance of 57.4%, and isotope 2 has a mass of 122.9042 amu. Find the atomic mass of this element and identify it.

David C.
Numerade Educator

Problem 78

An element has four naturally occurring isotopes with the masses and natural abundances given here. Find the atomic mass of the element and identify it.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 79

Bromine has two naturally occurring isotopes (Br-79 and Br-81) and an atomic mass of 79.904 amu. The mass of Br-81 is 80.9163 amu, and its natural abundance is 49.31%. Calculate the mass and natural
abundance of Br-79.

Ernest W.
Numerade Educator

Problem 80

Silicon has three naturally occurring isotopes (Si-28, Si-29, and Si-30). The mass and natural abundance of Si-28 are 27.9769 amu and 92.2%, respectively. The mass and natural abundance of Si-29 are 28.9765 amu and 4.67%, respectively. Find the mass and natural abundance of Si-30.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 81

Use the mass spectrum of europium shown here to determine the atomic mass of europium.

A. Elizabeth H.
Numerade Educator

Problem 82

Use the mass spectrum of rubidium shown here to determine the atomic mass of rubidium.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 83

How many sulfur atoms are there in 5.52 mol of sulfur?

Ernest W.
Numerade Educator

Problem 84

How many moles of aluminum do 3.7 * 1024 aluminum atoms represent?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 85

What is the amount, in moles, of each elemental sample?

a. 11.8 g Ar
b. 3.55 g Zn
c. 26.1 g Ta
d. 0.211 g Li

Ernest W.
Numerade Educator

Problem 86

What is the mass, in grams, of each elemental sample?

a. 2.3 * 103 mol Sb
b. 0.0355 mol Ba
c. 43.9 mol Xe
d. 1.3 mol W

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 87

How many silver atoms are there in 3.78 g of silver?

Ernest W.
Numerade Educator

Problem 88

What is the mass of 4.91 * 1021 platinum atoms?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 89

Calculate the number of atoms in each sample.

a. 5.18 g P
b. 2.26 g Hg
c. 1.87 g Bi
d. 0.082 g Sr

Ernest W.
Numerade Educator

Problem 90

Calculate the number of atoms in each sample.

a. 14.955 g Cr
b. 39.733 g S
c. 12.899 g Pt
d. 97.552 g Sn

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 91

Calculate the mass, in grams, of each sample.

a. 1.1 * 1023 gold atoms
b. 2.82 * 1022 helium atoms
c. 1.8 * 1023 lead atoms
d. 7.9 * 1021 uranium atoms

Ernest W.
Numerade Educator

Problem 92

Calculate the mass, in kg, of each sample.

a. 7.55 * 1026 cadmium atoms
b. 8.15 * 1027 nickel atoms
c. 1.22 * 1027 manganese atoms
d. 5.48 * 1029 lithium atoms

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 93

How many carbon atoms are there in a diamond (pure carbon) with a mass of 52 mg?

Ernest W.
Numerade Educator

Problem 94

How many helium atoms are there in a helium blimp containing 536 kg of helium?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 95

Calculate the average mass, in grams, of one platinum atom.

Ernest W.
Numerade Educator

Problem 96

Using scanning tunneling microscopy, scientists at IBM wrote the initials of their company with 35 individual xenon atoms (as shown below). Calculate the total mass of these letters in grams.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 97

A 7.83-g sample of HCN contains 0.290 g of H and 4.06 g of N.
Find the mass of carbon in a sample of HCN with a mass of 3.37 g.

Ernest W.
Numerade Educator

Problem 98

The ratio of sulfur to oxygen by mass in SO2 is 1.0:1.0.

a. Find the ratio of sulfur to oxygen by mass in SO3.
b. Find the ratio of sulfur to oxygen by mass in S2O.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 99

Use the mass spectrum of lead shown here to estimate the atomic mass of lead. Estimate the mass and percent intensity values from the graph to three significant figures.

Charotte M.
Numerade Educator

Problem 100

Use the mass spectrum of mercury shown here to estimate the atomic mass of mercury. Estimate the masses and percent intensity values from the graph to three significant figures.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 101

Nuclei with the same number of neutrons but different mass numbers are called isotones. Write the symbols of four isotones of 236Th.

Charotte M.
Numerade Educator

Problem 102

Fill in the blanks to complete the table.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 103

A penny has a thickness of approximately 1.0 mm. If you stacked Avogadro"s number of pennies one on top of the other on Earth"s surface, how far would the stack extend (in km)? For comparison, the sun is about 150 million km from Earth and the nearest star, Proxima Centauri, is about 40 trillion km from Earth.

Ernest W.
Numerade Educator

Problem 104

Consider the stack of pennies in Problem 103. How much money (in dollars) would this represent? If this money were equally distributed among the world"s population of 6.5 billion people, how much would each person receive? Would each person be a millionaire? A billionaire? A trillionaire?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 105

A pure copper sphere has a radius of 0.935 in. How many copper atoms does it contain? The volume of a sphere is (4>3) pr3, and the density of copper is 8.96 g>cm3.

Ernest W.
Numerade Educator

Problem 106

A pure titanium cube has an edge length of 2.78 in. How many titanium atoms does it contain? Titanium has a density of 4.50 g>cm3.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 107

A 67.2-g sample of a gold and palladium alloy contains 2.49 * 1023 atoms. What is the composition (by mass) of the alloy?

Ernest W.
Numerade Educator

Problem 108

Common brass is a copper and zinc alloy containing 37.0% zinc by mass and having a density of 8.48 g>cm3. A fitting composed of common brass has a total volume of 112.5 cm3. How many atoms (copper and zinc) does the fitting contain?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 109

The U.S. Environmental Protection Agency (EPA) sets limits on healthful levels of air pollutants. The maximum level that the EPA considers safe for lead air pollution is 1.5 mg>m3. If your lungs were filled with air containing this level of lead, how many lead atoms would be in your lungs? (Assume a total lung volume of 5.50 L.)

Ernest W.
Numerade Educator

Problem 110

Pure gold is usually too soft for jewelry, so it is often alloyed with other metals. How many gold atoms are in a 0.255-ounce 18 K gold bracelet? (18 K gold is 75% gold by mass.)

Charotte M.
Numerade Educator

Problem 111

Silver is composed of two naturally occurring isotopes: Ag-107 (51.839%) and Ag-109. The ratio of the masses of the two isotopes is 1.0187. What is the mass of Ag-107?

David C.
Numerade Educator

Problem 112

To the right is a representation of 50 atoms of a fictitious element called westmontium (Wt). The red spheres represent Wt-296, the blue spheres Wt-297, and the green spheres Wt-298.

a. Assuming that the sample is statistically representative of a naturally occurring sample, calculate the percent natural abundance of each Wt isotope.
b. Draw the mass spectrum for a naturally occurring sample of Wt.
c. The mass of each Wt isotope is measured relative to C-12 and tabulated here. Use the mass of C-12 to convert each of the masses to amu and calculate the atomic mass of Wt.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 113

The ratio of oxygen to nitrogen by mass in NO2 is 2.29. The ratio of fluorine to nitrogen by mass in NF3 is 4.07. Find the ratio of oxygen to fluorine by mass in OF2.

Ernest W.
Numerade Educator

Problem 114

Naturally occurring cobalt consists of only one isotope, 59Co, whose relative atomic mass is 58.9332. A synthetic radioactive isotope of cobalt, 60Co, relative atomic mass 59.9338, is used in radiation therapy for cancer. A 1.5886-g sample of cobalt has an apparent 'atomic mass' of 58.9901. Find the mass of 60Co in this sample.

Charotte M.
Numerade Educator

Problem 115

A 7.36-g sample of copper is contaminated with an additional 0.51 g of zinc. Suppose an atomic mass measurement is performed on this sample. What would be the apparent measured atomic mass?

Ernest W.
Numerade Educator

Problem 116

The ratio of the mass of O to the mass of N in N2O3 is 12:7. Another binary compound of nitrogen has a ratio of O to N of 16:7. What is its formula? What is the ratio of O to N in the next member of this series of compounds?

David C.
Numerade Educator

Problem 117

Naturally occurring magnesium has an atomic mass of 24.312 and consists of three isotopes. The major isotope is 24Mg, natural abundance 78.99%, relative atomic mass 23.98504. The next most abundant isotope is 26Mg, relative atomic mass 25.98259. The third most abundant isotope is 25Mg whose natural abundance is in the ratio of 0.9083 to that of 26Mg. Find the relative atomic mass of 25Mg.

Charotte M.
Numerade Educator

Problem 118

In Section 1.10, it was stated that 1 mol of sand grains would cover the state of Texas to several feet. Estimate how many feet by assuming that the sand grains are roughly cube-shaped, each one with an edge length of 0.10 mm. Texas has a land area of 268,601 sq mi.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 119

Use the concepts in this chapter to obtain an estimate for the number of atoms in the universe. Make the following assumptions: (a) All of the atoms in the universe are hydrogen atoms in
stars. (This is not a ridiculous assumption because over threefourths of the atoms in the universe are in fact hydrogen. Gas and dust between the stars represent only about 15% of the visible
matter of our galaxy, and planets compose a far smaller fraction.) (b) The sun is a typical star composed of pure hydrogen with a density of 1.4 g>cm3 and a radius of 7 * 108 m. (c) Each of the roughly 100 billion stars in the Milky Way galaxy contains the same number of atoms as our sun. (d) Each of the 10 billion galaxies in the visible universe contains the same number of atoms as our Milky Way galaxy.

A. Elizabeth H.
Numerade Educator

Problem 120

A volatile liquid (one that readily evaporates) is put into a jar, and the jar is then sealed. Does the mass of the sealed jar and its contents change upon the vaporization of the liquid?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 121

The diagram to the right represents solid carbon dioxide, also known as dry ice. Which of the diagrams below best represents the dry ice after it has sublimed into a gas?

A. Elizabeth H.
Numerade Educator

Problem 122

Use triangles to represent atoms of element A and circles to represent atoms of element B. Draw an atomic level view of a homogeneous mixture of elements A and B. Draw an atomic view of the compound AB in a liquid state (molecules close together). Draw an atomic view of the compound AB after it has undergone a physical change (such as evaporation). Draw an atomic view of the compound after it has undergone a chemical change (such as decomposition of AB into A and B).

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 123

Identify each statement as being most like an observation, a law, or a theory.

a. All coastal areas experience two high tides and two low tides each day.
b. The tides in Earth"s oceans are caused mainly by the gravitational attraction of the moon.
c. Yesterday, high tide in San Francisco Bay occurred at 2:43 am and 3:07 pm
d. Tides are higher at the full moon and new moon than at other times of the month.

A. Elizabeth H.
Numerade Educator

Problem 124

The mole is defined as the amount of a substance containing the same number of particles as exactly 12 g of C-12. The amu is defined as 1>12 of the mass of an atom of C-12. Why is it important that both of these definitions reference the same isotope? What would be the result, for example, of defining the mole with respect to C-12, but the amu with respect to Ne-20?

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 125

Without doing any calculations, determine which of the samples contains the greatest amount of the element in moles. Which contains the greatest mass of the element?

a. 55.0 g Cr
b. 45.0 g Ti
c. 60.0 g Zn

Ernest W.
Numerade Educator

Problem 126

Using white and black circles to represent different kinds of atoms, make a drawing that accurately represents each sample of matter: a solid element, a liquid compound, and a heterogeneous mixture. Make a drawing (clearly showing before and after) depicting your liquid compound undergoing a physical change. Make a drawing depicting your solid element undergoing a chemical change.

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 127

In a naturally occurring sample, 19.8% of boron atoms have 5 neutrons and 80.2% have 6 neutrons. What is the mass number of each boron isotope? Sketch a sample of 10 atoms that is nearly representative of a natural sample. What is the average mass of the atoms in your drawing? What is the atomic mass of boron? (Boron-10 has a mass of 10.01294 amu, and boron-11 has a mass of 11.00931 amu.)

A. Elizabeth H.
Numerade Educator

Problem 128

In complete sentences, describe the similarities and differences between:

a. different isotopes of an element
b. a neutral atom and an ion of the same element

ES
Eugene S.
University of Minnesota - Twin Cities

Problem 129

Calculate the mass in grams of one mole of each of the following (the mass of a single item is given in parentheses): electrons (9.10938 * 10-28 g), protons (1.67262 * 10-24 g), neutrons (1.67493 * 10-24 g), atoms of carbon-12 (1.992646 * 10-23 g), and doughnuts (74 g). Compare the mass of one mole of carbon-12 atoms to the sum of the masses of the particles that it contains. If the doughnut mentioned in this question were made entirely of carbon, how many atoms would it contain?

Charotte M.
Numerade Educator

Problem 130

The U.S. Environmental Protection Agency (U.S. EPA) monitors air quality in the United States. Lead is among the pollutants regularly monitored and regulated. Lead is released into the atmosphere primarily by the processing of metals ores containing lead and by lead-based battery manufacturing. The effects of too much exposure to lead include neurological damage and cardiovascular disease. Because of the Clean Air Act and its amendments, the amounts of lead in air have been decreasing for many years. The chart below shows the lead concentration in air in the United States from 2000 to 2014. Examine the data and answer the questions below.

ES
Eugene S.
University of Minnesota - Twin Cities