Chemistry The Molecular Science

John W. Moore, Conrad L. Stanitski

Chapter 1

The Nature of Chemistry - all with Video Answers

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Chapter Questions

Problem 1

What is meant by nanoscale? Why is structure at the nanoscale important?

Satpal Satpal

Satpal Satpal

Numerade Educator

Problem 2

Choose an object in your room, such as a cell phone or television set. Write down five qualitative observations and five quantitative observations regarding the object you chose.

Nicole Smina

Numerade Educator

Problem 3

What are three important characteristics of a scientific law? Name two laws that were mentioned in this chapter. State each of the laws that you named.

Nicole Smina

Numerade Educator

Problem 4

How does a scientific theory differ from a law? How are theories and models related?

Nicole Smina

Numerade Educator

Problem 5

What is the unique perspective that chemists use to make sense out of the material world? Give at least one example of how that perspective can be applied to a significant problem.

Pronoy Sinha

Numerade Educator

Problem 6

Give two examples of situations in which purity of a chemical substance is important.

Nicole Smina

Numerade Educator

Problem 7

Make a list of at least four issues faced by our society that require scientific studies and scientific data before a democratic society can make informed, rational decisions. Exchange lists with another student and evaluate the quality of each other's choices.

Aadit Sharma

Numerade Educator

Problem 8

Make a list of at least four questions you have wondered about that may involve chemistry. Compare your list with a list from another student taking the same chemistry course. Evaluate the quality of each other's questions and decide how "chemical" they are.

Nicole Smina

Numerade Educator

Problem 9

Which of these statements are qualitative? Which are quantitative? Explain your choice in each case.
(a) Sodium is a silvery-white metal.
(b) Aluminum melts at $660^{\circ} \mathrm{C}$.
(c) Carbon makes up about $23 \%$ of the human body by mass.
(d) Pure carbon occurs in different forms: graphite, diamond, and fullerenes.

Nicole Smina

Numerade Educator

Problem 10

Which of the these statements are qualitative? Which are quantitative? Explain your choice in each case.
(a) The atomic mass of carbon is $12.011(12.011$ atomic mass units).
(b) Pure aluminum is a silvery-white metal that is nonmagnetic, has a low density, and does not produce sparks when struck.
(c) Sodium has a density of $0.968 \mathrm{~g} / \mathrm{mL}$.
(d) In animals the sodium cation, $\mathrm{Na}^{+}$, is the main extracellular cation and is important for nerve function.

Nicole Smina

Numerade Educator

Problem 11

The elements sulfur and bromine are shown in the photograph. Based on the photograph, describe as many properties of each sample as you can. Are any properties the same? Which properties are different?

Nicole Smina

Numerade Educator

Problem 12

In the accompanying photo, you see a crystal of the mineral calcite surrounded by piles of calcium and carbon, two of the elements that combine to make the mineral. (The other element combined in calcite is oxygen.) Based on the photo, describe some of the physical properties of the elements and the mineral. Are any properties the same? Are any properties different?

Nicole Smina

Numerade Educator

Problem 13

The melting point of gallium is $29.76^{\circ} \mathrm{C}$. If you hold a sample of gallium in your hand, will it melt? Explain briefly.

Nicole Smina

Numerade Educator

Problem 14

These temperatures are measured at various locations during the same day in the winter in North America: $-10^{\circ} \mathrm{C}$ at Montreal, $28^{\circ} \mathrm{F}$ at Chicago, $20^{\circ} \mathrm{C}$ at Charlotte, and $40^{\circ} \mathrm{F}$ at Philadelphia. Which city is the warmest? Which city is the coldest?

Nicole Smina

Numerade Educator

Problem 15

A crystal of fluorite (a mineral that contains calcium and fluorine) has a mass of $2.83 \mathrm{~g}$. What is this mass in kilograms? Give the symbols for the elements in this crystal.

Nicole Smina

Numerade Educator

Problem 16

Suppose a room is $18 \mathrm{~m}$ long, $15 \mathrm{~m}$ wide, and the distance from floor to ceiling is $2.9 \mathrm{~m}$. What is the room's volume in cubic meters? In cubic centimeters? In liters?

Nicole Smina

Numerade Educator

Problem 17

The current world record for the $100-\mathrm{m}$ dash is $9.58 \mathrm{sec}-$ onds held by Usain Bolt of Jamaica. Calculate whether he could have been arrested for exceeding a $25 \mathrm{mi} / \mathrm{h}$ speed limit while setting that record.

Nicole Smina

Numerade Educator

Problem 18

Body mass index (BMI) is the ratio of a person's mass (kg) divided by the square of the height (m). In general, a $\mathrm{BMI}>25$ indicates that the person is overweight.
(a) Calculate the BMI of someone who is 76.0 in tall and weighs $176 \mathrm{lb}$.
(b) Should the person be considered as being overweight? Explain.

Nicole Smina

Numerade Educator

Problem 19

How many significant figures are present in these measured quantities?
(a) $1374 \mathrm{~kg}$
(b) $0.00348 \mathrm{~s}$
(c) $5.619 \mathrm{~mm}$
(d) $2.475 \times 10^{-3} \mathrm{~cm}$
(e) 33
(f) $2300 \mathrm{~m}$

Nicole Smina

Numerade Educator

Problem 20

How many significant figures are present in these measured quantities?
(a) $1.022 \times 10^{2} \mathrm{~km}$
(b) $34 \mathrm{~m}^{2}$
(c) $0.042 \mathrm{~L}$
(d) $28.2^{\circ} \mathrm{C}$
(e) $323 . \mathrm{mg}$
(f) $420 \mathrm{~g}$

Nicole Smina

Numerade Educator

Problem 21

Perform these calculations and express the result with the proper number of significant figures.
(a) $\frac{4.850 \mathrm{~g}-2.34 \mathrm{~g}}{1.3 \mathrm{~mL}}$
(b) $V=\frac{4}{3} \pi r^{3}$ where $r=4.112 \mathrm{~cm}$
(c) $\left(4.66 \times 10^{-3}\right) \times 4.666$
(d) $\frac{0.003400}{65.2}$

Aadit Sharma

Numerade Educator

Problem 22

Perform these calculations and express the result with the proper number of significant figures.
(a) $2221.05-\frac{3256.5}{3.20}$
(b) $343.2 \times\left(2.01 \times 10^{-3}\right)$
(c) $S=4 \pi r^{2}$ where $r=2.55 \mathrm{~cm}$
(d) $\frac{2802}{15}-(0.0025 \times 10,000 .)$

Emily Himsel

Numerade Educator

Problem 23

A $105.5-\mathrm{g}$ sample of a metal was placed into water in a graduated cylinder, and it completely submerged. The water level rose from $25.4 \mathrm{~mL}$ to $37.2 \mathrm{~mL}$. Use data in Table 1.1 to identify the metal.

Nicole Smina

Numerade Educator

Problem 24

An irregularly shaped piece of lead weighs $10.0 \mathrm{~g} .$ It is carefully lowered into a graduated cylinder containing $30.0 \mathrm{~mL}$ ethanol, and it sinks to the bottom of the cylinder. To what volume reading does the ethanol rise?

Nicole Smina

Numerade Educator

Problem 25

An unknown sample of a metal is $1.0 \mathrm{~cm}$ thick, $2.0 \mathrm{~cm}$ wide, and $10.0 \mathrm{~cm}$ long. Its mass is $54.0 \mathrm{~g}$. Use data in Table 1.1 to identify the metal. (Remember that $1 \mathrm{~cm}^{3}=$ 1 mL.)

Nicole Smina

Numerade Educator

Problem 26

Calculate the volume of a $23.4-\mathrm{g}$ sample of bromobenzene, density $=1.49 \mathrm{~g} / \mathrm{mL}$.

Nicole Smina

Numerade Educator

Problem 27

Calculate the mass of a sodium chloride crystal if the dimensions of the crystal are $10 \mathrm{~cm}$ thick by $12 \mathrm{~cm}$ long by $15 \mathrm{~cm}$ wide. (Remember that $1 \mathrm{~cm}^{3}=1 \mathrm{~mL}$.)

Nicole Smina

Numerade Educator

Problem 28

Calculate the volume occupied by a $4.33-\mathrm{g}$ sample of iron.

Nicole Smina

Numerade Educator

Problem 29

In each case, identify the italicized property as a physical or chemical property. Give a reason for your choice.
(a) The normal color of the element bromine is red-orange.
(b) Iron is transformed into rust in the presence of air and water.
(c) Dynamite can explode.
(d) Aluminum metal, the shiny "foil" you use in the kitchen, melts at $660^{\circ} \mathrm{C}$.

Nicole Smina

Numerade Educator

Problem 30

In each case, identify the italicized property as a physical or a chemical property. Give a reason for your choice.
(a) Dry ice sublimes (changes directly from a solid to a gas) at $-78.6^{\circ} \mathrm{C}$
(b) Methanol (methyl alcohol) burns in air with a colorless flame.
(c) Sugar is soluble in water.
(d) Hydrogen peroxide, $\mathrm{H}_{2} \mathrm{O}_{2}$, decomposes to form oxygen, $\mathrm{O}_{2},$ and water, $\mathrm{H}_{2} \mathrm{O} .$

Nicole Smina

Numerade Educator

Problem 31

In each case, describe the change as a chemical or physical change. Give a reason for your choice.
(a) A cup of household bleach changes the color of your favorite T-shirt from purple to pink.
(b) The fuels in the space shuttle (hydrogen and oxygen) combine to give water and provide the energy to lift the shuttle into space.
(c) An ice cube in your glass of lemonade melts.

Nicole Smina

Numerade Educator

Problem 32

In each case, describe the change as a chemical or physical change. Give a reason for your choice.
(a) Salt dissolves when you add it to water.
(b) Food is digested and metabolized in your body.
(c) Crystalline sugar is ground into a fine powder.
(d) When potassium is added to water there is a purplishpink flame and the water becomes basic (alkaline).

Nicole Smina

Numerade Educator

Problem 33

In each situation, decide whether a chemical reaction is releasing energy and causing work to be done, or whether an outside source of energy is forcing a chemical reaction to occur.
(a) Your body converts excess intake of food into fat molecules.
(b) Sodium reacts with water as shown in Figure 1.5 .
(c) Sodium azide in an automobile air bag decomposes, causing the bag to inflate.
(d) An egg is hard-boiled in a pan on your kitchen stove.

Nicole Smina

Numerade Educator

Problem 34

While camping in the mountains you build a small fire out of tree limbs you find on the ground near your campsite. The dry wood crackles and burns brightly and warms you. Before slipping into your sleeping bag for the night, you put the fire out by dousing it with cold water from a nearby stream. Steam rises when the water hits the hot coals. Describe the physical and chemical changes in this scene.

Aadit Sharma

Numerade Educator

Problem 35

Small chips of iron are mixed with sand (see photo). Is this a homogeneous or heterogeneous mixture? Suggest a way to separate the iron and sand from each other.

Pahk Thepchatri

Pahk Thepchatri

Numerade Educator

Problem 36

Identify each of these as a homogeneous or a heterogeneous mixture.
(a) An asphalt (blacktop) road
(b) Clear ocean water
(c) Iced tea with ice cubes
(d) Filtered apple cider

Pronoy Sinha

Numerade Educator

Problem 37

Devise and describe an experiment to
(a) Separate table salt (sodium chloride) from water.
(b) Separate iron filings from small pieces of magnesium.
(c) Separate the element zinc from sugar (sucrose).

Pronoy Sinha

Numerade Educator

Problem 38

Devise and describe an experiment to
(a) Separate sucrose (table sugar) from water.
(b) Separate the element sulfur from table salt (sodium chloride).
(c) Separate iron filings from granular zinc.

Pronoy Sinha

Numerade Educator

Problem 39

For each of the changes described, decide whether two or more elements formed a compound or if a compound decomposed (to form elements or other compounds). Explain your reasoning in each case.
(a) Upon heating, a blue powder turned white and lost mass.
(b) A white solid forms three different gases when heated. The total mass of the gases is the same as that of the solid.

Pronoy Sinha

Numerade Educator

Problem 40

For each of the changes described, decide whether two or more elements formed a compound or if a compound decomposed (to form elements or other compounds). Explain your reasoning in each case.
(a) After a reddish-colored metal is placed in a flame, it turns black and has a higher mass.

Pronoy Sinha

Numerade Educator

Problem 41

Classify each of these as an element, a compound, a heterogeneous mixture, or a homogeneous mixture. Explain your choice in each case.
(a) Chunky peanut butter
(b) Distilled water
(c) Platinum
(d) Air

Nicole Smina

Numerade Educator

Problem 42

Classify each of these as an element, a compound, a heterogeneous mixture, or a homogeneous mixture. Explain your choice in each case.
(a) Table salt (sodium chloride)
(b) Methane (which burns in pure oxygen to form only carbon dioxide and water)
(c) Chocolate chip cookie
(d) Silicon

Nicole Smina

Numerade Educator

Problem 43

A black powder is placed in a long glass tube. Hydrogen gas is passed into the tube so that the hydrogen sweeps out all other gases. The powder is then heated with a Bunsen burner. The powder turns red-orange, and water vapor can be seen condensing at the unheated far end of the tube. The red-orange color remains after the tube cools.
(a) Was the original black substance an element? Explain briefly.
(b) Is the new red-orange substance an element? Explain briefly.

Pronoy Sinha

Numerade Educator

Problem 44

A finely divided black substance is placed in a glass tube filled with air. When the tube is heated with a Bunsen burner, the black substance turns red-orange. The total mass of the red-orange substance is greater than that of the black substance.
(a) Can you conclude that the black substance is an element? Explain briefly.
(b) Can you conclude that the red-orange substance is a compound? Explain briefly.

Pronoy Sinha

Numerade Educator

Problem 45

The image of part of a DNA molecule below was obtained with a scanning tunneling microscope. The scales are given in hundreds of Angstrom units. Is this image at the macroscale, the microscale, or the nanoscale?

Nicole Smina

Numerade Educator

Problem 46

The image below shows several examples of tobacco mosaic virus. Is this virus at the macroscale, the microscale, or the nanoscale? (The scale bar at the bottom of the image is $100 \mathrm{nm}$ long.)

Nicole Smina

Numerade Educator

Problem 47

When you open a can of a carbonated drink, the carbon dioxide gas inside expands rapidly as it rushes from the can. Describe this process in terms of the kineticmolecular theory.

Nicole Smina

Numerade Educator

Problem 48

Sometimes, after clothes are washed, they are hung in the sun to dry. Describe the change or changes that occur in terms of the kinetic-molecular theory. Are the changes that occur physical or chemical changes?

Pronoy Sinha

Numerade Educator

Problem 49

Sucrose has to be heated to a high temperature before it caramelizes. Use the kinetic-molecular theory to explain why sugar caramelizes only at high temperatures.

Nicole Smina

Numerade Educator

Problem 50

Give a nanoscale interpretation of the fact that at the melting point the density of solid mercury is greater than the density of liquid mercury, and at the boiling point the density of liquid mercury is greater than the density of gaseous mercury.

Pronoy Sinha

Numerade Educator

Problem 51

Explain in your own words, by writing a short paragraph, how the atomic theory explains conservation of mass during a chemical reaction and during a physical change.

Aadit Sharma

Numerade Educator

Problem 52

Explain in your own words, by writing a short paragraph, how the atomic theory explains constant composition of chemical compounds.

Aadit Sharma

Numerade Educator

Problem 53

Explain in your own words, by writing a short paragraph, how the atomic theory predicts the law of multiple proportions.

Aadit Sharma

Numerade Educator

Problem 54

The element chromium forms three different oxides (that contain only chromium and oxygen). The percentage of chromium (number of grams of chromium in $100 \mathrm{~g}$ oxide) in these compounds is $52.0 \%, 68.4 \%,$ and $76.5 \%$. Do these data conform to the law of multiple proportions? Explain why or why not.

Aadit Sharma

Numerade Educator

Problem 55

Write a chemical formula for each substance, and draw a picture of how the nanoscale particles are arranged at room temperature.
(a) Water, a liquid whose molecules contain two hydrogen atoms and one oxygen atom each
(b) Nitrogen, a gas that consists of diatomic molecules

Pronoy Sinha

Numerade Educator

Problem 56

Write a chemical formula for each substance and draw a picture of how the nanoscale particles are arranged at room temperature.
(a) Iodine, a solid that consists of diatomic molecules
(b) Ozone, a gas that consists of triatomic molecules
(c) Helium
(d) Carbon dioxide

Pronoy Sinha

Numerade Educator

Problem 57

Write a chemical formula for each substance and draw a picture of how the nanoscale particles are arranged at room temperature.
(a) Iodine, a solid that consists of diatomic molecules
(b) Ozone, a gas that consists of triatomic molecules
(c) Helium
(d) Carbon dioxide

Pronoy Sinha

Numerade Educator

Problem 58

Write a nanoscale representation and a symbolic representation and describe what happens at the macroscale when carbon monoxide reacts with oxygen to form carbon dioxide.

Pronoy Sinha

Numerade Educator

Problem 59

Write a nanoscale representation and a symbolic representation and describe what happens at the macroscale when iodine sublimes (passes directly from solid to gas with no liquid formation) to form iodine vapor.

Pronoy Sinha

Numerade Educator

Problem 60

Write a nanoscale representation and a symbolic representation and describe what happens at the macroscale when bromine evaporates to form bromine vapor.

Pronoy Sinha

Numerade Educator

Problem 61

Name and give the symbols for two elements that
(a) Are metals.
(b) Are nonmetals.
(c) Are metalloids.
(d) Are alkaline-earth elements.

Nicole Smina

Numerade Educator

Problem 62

Name and give the symbols for two elements that
(a) Are gases at room temperature.
(b) Are solids at room temperature.
(c) Do not consist of molecules.
(d) Consist of diatomic molecules.

Nicole Smina

Numerade Educator

Problem 63

Name and give symbols for three transition metals in the fourth period. Look up each of your choices in a dictionary, a book such as The Handbook of Chemistry and Physics, or on the Internet, and make a list of their properties. Also list the uses of each element.

Pronoy Sinha

Numerade Educator

Problem 64

Name two halogens. Look up each of your choices in a dictionary, in a book such as The Handbook of Chemistry and Physics, or on the Internet, and make a list of their properties. Also list any uses of each element that are given by the source.

Pronoy Sinha

Numerade Educator

Problem 65

How many elements are there in Group $4 \mathrm{~A}$ of the periodic table? Give the name and symbol of each of these elements. Tell whether each is a metal, nonmetal, or metalloid.

Nicole Smina

Numerade Educator

Problem 66

How many elements are there in the fourth period of the periodic table? Give the name and symbol of each of these elements. Tell whether each is a metal, metalloid, or nonmetal.

Nicole Smina

Numerade Educator

Problem 67

The symbols for the four elements whose names begin with the letter I are In, I, Ir, and Fe. Match each symbol with one of these phrases below.
(a) A halogen
(b) A main-group metal
(c) A transition metal in Period 6
(d) A transition metal in Period 4

Nicole Smina

Numerade Educator

Problem 68

The symbols for four of the eight elements whose names begin with the letter $\mathrm{S}$ are $\mathrm{Si}$, $\mathrm{Ag}, \mathrm{Na},$ and $\mathrm{S} .$ Match each symbol with one of these phrases below.
(a) A solid nonmetal
(b) An alkali metal
(c) A transition metal
(d) A metalloid

Nicole Smina

Numerade Educator

Problem 69

Use the periodic table to identify these elements:
(a) Name an element in Group $2 \mathrm{~A}$.
(b) Name an element in the third period.
(c) What element is in the second period in Group $4 \mathrm{~A}$ ?
(d) What element is in the third period in Group $6 \mathrm{~A}$ ?
(e) What halogen is in the fifth period?
(f) What alkaline-earth element is in the third period?
(g) What noble gas element is in the fourth period?
(h) What nonmetal is in Group $6 \mathrm{~A}$ and the second period?
(i) Name a metalloid in the fourth period.

Aadit Sharma

Numerade Educator

Problem 70

Use the periodic table to identify these elements:
(a) Name an element in Group $2 \mathrm{~B}$.
(b) Name an element in the fifth period.
(c) What element is in the sixth period in Group $4 \mathrm{~A} ?$
(d) What element is in the third period in Group $5 \mathrm{~A}$ ?
(e) What alkali metal is in the third period?
(f) What noble gas is in the fifth period?
(g) Name the element in Group $6 \mathrm{~A}$ and the fourth period. Is it a metal, nonmetal, or metalloid?
(h) Name a metalloid in Group $5 \mathrm{~A}$.

Aadit Sharma

Numerade Educator

Problem 71

Which types of compounds contain the majority of the oxygen found in the human body?

Pronoy Sinha

Numerade Educator

Problem 72

(a) In what form are metals found in the body, as atoms or as ions?
(b) What are two uses for metals in the human body?

Nicole Smina

Numerade Educator

Problem 73

Distinguish between major minerals and trace elements.

Pronoy Sinha

Numerade Educator

Problem 74

Name a mineral that is essential at smaller concentrations but toxic at higher concentrations.

Nicole Smina

Numerade Educator

Problem 75

Classify the information in each of these statements as quantitative or qualitative and as relating to a physical or chemical property.
(a) A white chemical compound has a mass of $1.456 \mathrm{~g}$. When placed in water containing a dye, it causes the red color of the dye to fade to colorless.
(b) A sample of lithium metal, with a mass of $0.6 \mathrm{~g}$, was placed in water. The metal reacted with the water to produce the compound lithium hydroxide and the element hydrogen.

Nicole Smina

Numerade Educator

Problem 76

Classify the information in each of these statements as quantitative or qualitative and as relating to a physical or chemical property.
(a) A liter of water, colored with a purple dye, was passed through a charcoal filter. The charcoal adsorbed the dye, and colorless water came through. Later, the purple dye was removed from the charcoal and retained its color.
(b) When a white powder dissolved in a test tube of water, the test tube felt cold. Hydrochloric acid was then added, and a white solid formed.

Pronoy Sinha

Numerade Educator

Problem 77

The label on a bale of mulch indicates a volume of $1.45 \mathrm{ft}^{3}$. The label also states that the mulch in the bale will cover an area of a garden $6 \mathrm{ft} \times 6 \mathrm{ft}$ to a depth of 1 in. Account for the discrepancy in the given volumes.

Pronoy Sinha

Numerade Educator

Problem 78

The density of a solution of sulfuric acid is $1.285 \mathrm{~g} / \mathrm{cm}^{3}$, and it is $38.08 \%$ acid by mass. Calculate the volume of solution (in $\mathrm{mL}$ ) that contains $125 \mathrm{~g}$ of sulfuric acid.

Pronoy Sinha

Numerade Educator

Problem 79

In addition to the metric units of $\mathrm{nm}$ and $\mathrm{pm}$, a commonly used unit is the angstrom, where $1 \AA=1 \times 10^{-10} \mathrm{~m}$. If the distance between a $\mathrm{Pt}$ atom and an $\mathrm{N}$ atom in a compound is $1.97 \AA$, what is the distance in $\mathrm{nm}$ ? In pm?

Pronoy Sinha

Numerade Educator

Problem 80

The cancer drug cisplatin contains $65.0 \%$ platinum. You have a $1.53-\mathrm{g}$ sample of the compound; calculate the mass of platinum it contains.

Nicole Smina

Numerade Educator

Problem 81

The density of solid potassium is $0.86 \mathrm{~g} / \mathrm{mL}$. The density of solid calcium is $1.55 \mathrm{~g} / \mathrm{mL},$ almost twice as great. However, the mass of a potassium atom is only slightly less than the mass of a calcium atom. Provide a nanoscale explanation of these facts.

Pronoy Sinha

Numerade Educator

Problem 82

The density of gaseous helium at $25^{\circ} \mathrm{C}$ and normal atmospheric pressure is $1.64 \times 10^{-4} \mathrm{~g} / \mathrm{mL}$. At the same temperature and pressure the density of argon gas is $1.63 \times 10^{-3} \mathrm{~g} / \mathrm{mL}$. The mass of an atom of argon is almost exactly ten times the mass of an atom of helium. Provide a nanoscale explanation of why the densities differ as they do.

Pronoy Sinha

Numerade Educator

Problem 83

The gauge number of a wire is related to the diameter of the wire. Suppose you have a 10.0 -lb spool of 12 -gauge aluminum wire (diameter 0.0808 in). Calculate the length of wire (in meters) on the spool. Assume that the wire is a cylinder $\left(V=\pi r^{2} \ell,\right.$ where $V$ is the volume, $r$ is the radius, and $\ell$ is the length) and obtain the density of aluminum from Table 1.1. $(1$ in $=2.54 \mathrm{~cm} ; 1 \mathrm{lb}=453.59 \mathrm{~g})$

Pronoy Sinha

Numerade Educator

Problem 84

The dimensions of aluminum foil in a box for sale at a supermarket are $66 \frac{2}{3}$ yards by 12 inches. The mass of the foil is $0.83 \mathrm{~kg} .$ Calculate the thickness of the foil (in $\mathrm{cm}$ ). $(1$ in $=2.54 \mathrm{~cm})$

Pronoy Sinha

Numerade Educator

Problem 85

Hexane (density $=0.66 \mathrm{~g} / \mathrm{cm}^{3}$ ), perfluorohexane (density $=1.669 \mathrm{~g} / \mathrm{cm}^{3}$ ), and water are immiscible liquids; that is, they do not dissolve in one another. You place $10 \mathrm{~mL}$ of each in a graduated cylinder, along with pieces of high-density polyethylene (HDPE, density $0.97 \mathrm{~g} / \mathrm{mL}$ ), polyvinyl chloride (PVC, density = $\left.1.36 \mathrm{~g} / \mathrm{cm}^{3}\right),$ and Teflon (density $\left.=2.3 \mathrm{~g} / \mathrm{cm}^{3}\right) .$ None of these common plastics dissolves in these liquids. Describe what you expect to see.

Pronoy Sinha

Numerade Educator

Problem 86

You can figure out whether a substance floats or sinks if you know its density and the density of the liquid. In which of the liquids listed below will high-density polyethylene (HDPE) float? HDPE, a common plastic, has a density of $0.97 \mathrm{~g} / \mathrm{mL}$. It does not dissolve in any of these liquids.

Pronoy Sinha

Numerade Educator

Problem 87

Eleven of the elements in the periodic table are found in nature as gases at room temperature. List them. Where are they located in the periodic table?

Nicole Smina

Numerade Educator

Problem 88

Ten of the elements are $\mathrm{O}, \mathrm{H}, \mathrm{Ar}, \mathrm{Al}, \mathrm{Ca}, \mathrm{Br}, \mathrm{Ge}, \mathrm{K}, \mathrm{Cu}$ and $P$. Pick the one that best fits each description: (a) an alkali metal; (b) a noble gas; (c) a transition metal; (d) a metalloid; (e) a Group 1 nonmetal; (f) an alkaline-earth metal; $(\mathrm{g})$ a halogen; (h) a nonmetal that is a solid.

Nicole Smina

Numerade Educator

Problem 89

The periodic table shown below is color coded gray, blue, orange, and lavender. Identify the color of the area (or colors of the areas) in which you would expect to find each type of element.
(a) A colorless gas
(b) A solid that is ductile and malleable
(c) A solid that has poor electrical conductivity

Pronoy Sinha

Numerade Educator

Problem 90

The periodic table shown below is color coded gray, blue, orange, and lavender. Identify the color of the area (or colors of the areas) in which you would expect to find each type of element.
(a) A colorless gas
(b) A solid that is ductile and malleable
(c) A solid that has poor electrical conductivity

Aadit Sharma

Numerade Educator

Problem 91

Which two elements from this list exhibit the greatest similarity in physical and chemical properties? Explain your choice. $\mathrm{S}, \mathrm{Ga}, \mathrm{Se}, \mathrm{Ti}$

Nicole Smina

Numerade Educator

Problem 92

Which two elements from this list exhibit the greatest similarity in physical and chemical properties? Explain your choice. $\mathrm{Mg}, \mathrm{Br}, \mathrm{Si}, \mathrm{Sr}$.

Nicole Smina

Numerade Educator

Problem 93

In the past, when someone discovered a new substance, it was relatively easy to show that the substance was not an element, but quite difficult to prove that the substance was an element. Explain why this is so, and relate your explanation to the discussion of scientific laws and theories in Section $1-3$.

Pronoy Sinha

Numerade Educator

Problem 94

Soap can be made by mixing animal or vegetable fat with a concentrated solution of lye and heating it in a large vat. Suppose that $3.24 \mathrm{~kg}$ vegetable fat is placed in a large iron vat and then $50.0 \mathrm{~L}$ water and $5.0 \mathrm{~kg}$ lye (sodium hydroxide, $\mathrm{NaOH}$ ) are added. The vat is placed over a fire and heated for two hours, and soap forms.
(a) Classify each of the materials identified in the soapmaking process as a substance or a mixture. For each substance, indicate whether it is an element or a compound. For each mixture, indicate whether it is homogeneous or heterogeneous.
(b) Assuming that the fat and lye are completely converted into soap, what mass of soap is produced?
(c) What physical and chemical processes occur as the soap is made?

Pronoy Sinha

Numerade Educator

Problem 95

The densities of several elements are given in Table 1.1 .
(a) Of the elements nickel, gold, lead, and magnesium, which will float on liquid mercury at $20^{\circ} \mathrm{C} ?$
(b) Of the elements titanium, copper, iron, and gold, which will float highest on the mercury? That is, which element will have the smallest fraction of its volume below the surface of the liquid?

Nicole Smina

Numerade Educator

Problem 96

The element platinum has a solid-state structure in which platinum atoms are arranged in a cubic shape that repeats throughout the solid. The length of an edge of the cube is $392 \mathrm{pm}\left(1 \mathrm{pm}=1 \times 10^{-12} \mathrm{~m}\right) .$ Calculate the volume of the cube in cubic meters.

Pronoy Sinha

Numerade Educator

Problem 97

The compound sodium chloride has a solid-state structure in which there is a repeating cubic arrangement of sodium ions and chloride ions. The volume of the cube is $1.81 \times 10^{-22} \mathrm{~cm}^{3} .$ Calculate the length of an edge of the cube in $\mathrm{pm}\left(1 \mathrm{pm}=1 \times 10^{-12} \mathrm{~m}\right)$.

Pronoy Sinha

Numerade Educator

Problem 98

You are given a mixture of sand, sugar, and sulfur. Write a detailed description of a procedure that would completely separate each component from this mixture.

Aadit Sharma

Numerade Educator

Problem 99

You are given a mixture of sand, salt (sodium chloride), and naphthalene, a white solid that is not soluble in water. Write a detailed description of a procedure that would completely separate each component from this mixture.

Aadit Sharma

Numerade Educator

Problem 100

Using Table 1.1 , but without using your calculator, decide which has the larger mass:
(a) 20. $\mathrm{mL}$ butane or $20 . \mathrm{mL}$ bromobenzene
(b) 10. $\mathrm{mL}$ benzene or $1.0 \mathrm{~mL}$ gold
(c) $0.732 \mathrm{~mL}$ copper or $0.732 \mathrm{~mL}$ lead

Nicole Smina

Numerade Educator

Problem 101

Using Table 1.1 , but without using your calculator, decide which has the larger volume:
(a) $1.0 \mathrm{~g}$ ethanol or $1.0 \mathrm{~g}$ bromobenzene
(b) 10. g aluminum or $12 \mathrm{~g}$ water
(c) $20 \mathrm{~g}$ gold or $40 \mathrm{~g}$ magnesium

Pronoy Sinha

Numerade Educator

Problem 102

At $25^{\circ} \mathrm{C}$ the density of water is $0.997 \mathrm{~g} / \mathrm{mL},$ whereas the density of ice at $-10^{\circ} \mathrm{C}$ is $0.917 \mathrm{~g} / \mathrm{mL}$
(a) If a plastic soft-drink bottle (volume $=250 \mathrm{~mL}$ ) is completely filled with pure water, capped, and then frozen at $-10^{\circ} \mathrm{C},$ what volume will the solid occupy?
(b) What will the bottle look like when you take it out of the freezer?

Pronoy Sinha

Numerade Educator

Problem 103

When water alone (instead of engine coolant, which contains water and other substances) was used in automobile radiators to cool cast-iron engine blocks, it sometimes happened in winter that the engine block would crack, ruining the engine. Cast iron is not pure iron and is relatively hard and brittle. Explain in your own words how the engine block in a car might crack in cold weather.

Pronoy Sinha

Numerade Educator

Problem 104

Water does not dissolve in bromobenzene.
(a) If you pour $2 \mathrm{~mL}$ water into a test tube that contains $2 \mathrm{~mL}$ bromobenzene, which liquid will be on top?
(b) If you pour $2 \mathrm{~mL}$ ethanol carefully into the test tube containing bromobenzene and water described in part (a) without shaking or mixing the liquids, what will happen?
(c) What will happen if you thoroughly stir the mixture in part (b)?

Pronoy Sinha

Numerade Educator

Problem 105

Water does not mix with either benzene or bromobenzene
when it is stirred together with either of them, but benzene and bromobenzene do mix.
(a) If you pour $2 \mathrm{~mL}$ bromobenzene into a test tube, then add $2 \mathrm{~mL}$ water and stir, what would the test tube look like a few minutes later?
(b) Suppose you add $2 \mathrm{~mL}$ benzene to the test tube in part
(a), pouring the benzene carefully down the side of the tube so that the liquids do not mix. Describe the appearance of the test tube now.
(c) If the test tube containing all three liquids is thoroughly shaken and then allowed to stand for five minutes, what will the tube look like?

Aadit Sharma

Numerade Educator

Problem 106

The figure shows a nanoscale view of the atoms of mercury in a thermometer registering $10{ }^{\circ} \mathrm{C}$.
Which nanoscale drawing best represents the atoms in the liquid in this same thermometer at $90^{\circ} \mathrm{C} ?$ (Assume that the same volume of liquid is shown in each nanoscale drawing.)

Aadit Sharma

Numerade Educator

Problem 107

Answer these questions using figures (a) through (i). (Each question may have more than one answer.)

Aadit Sharma

Numerade Educator

Problem 108

Air mostly consists of diatomic molecules of nitrogen (about $80 \%$ ) and oxygen (about $20 \%$ ). Draw a nanoscale picture of a sample of air that contains a total of 10 molecules.

Pronoy Sinha

Numerade Educator

Problem 109

Most pure samples of metals are malleable, which means that if you try to grind up a sample of a metal by pounding on it with a hard object, the pieces of metal change shape but do not break apart. Solid samples of nonmetallic elements, such as sulfur or graphite, are often brittle and break into smaller particles when hit by a hard object. Devise a nanoscale theory about the structures of metals and nonmetals that can account for this difference in macroscale properties.

Aadit Sharma

Numerade Educator

Problem 110

Rivers add salt (sodium chloride, $\mathrm{NaCl}$ ) to the oceans of the world at a rate of approximately $2 \times 10^{16} \mathrm{~g} / \mathrm{yr}$. Assume that Earth is a sphere with a diameter of $8,000 \mathrm{mi}$, $67 \%$ of which is covered by oceans to a depth of $1 \mathrm{mi} .$ The average sodium chloride concentration of the oceans is $3 \% \mathrm{NaCl}$ by mass and the average density of seawater is $1.03 \mathrm{~g} / \mathrm{cm}^{3}$. If the rate at which the $\mathrm{NaCl}$ addition to the oceans has been constant, calculate the approximate age of the oceans. Comment on the reasonableness of your answer given that the age of Earth is $4.5 \times 10^{9}$ yr.

Narayan Hari

Numerade Educator

Problem 111

When $1.0000 \mathrm{~g}$ silver chloride $(\mathrm{AgCl})$ is all converted to silver iodide $(\mathrm{AgI}), 1.6381 \mathrm{~g} \mathrm{AgI}$ is formed. You know that an atom of iodine has 3.580 times the mass of an atom of chlorine; calculate the mass of silver in each sample. Also calculate the mass of chlorine in the $\mathrm{AgCl}$ sample and the mass of iodine in the AgI sample.

Tracy Tourville

Tracy Tourville

Numerade Educator

Problem 112

Rust (an oxide of iron) can be converted to iron metal by reacting it with aluminum metal to form an aluminum oxide. You know that an iron atom has 2.069 times the mass of an aluminum atom. The mass of rust is $35.48 \mathrm{~g}$ and, when all of the iron has been replaced by aluminum, the mass of the aluminum oxide is $22.65 \mathrm{~g} .$ Calculate the mass of oxygen in both samples. Also calculate the mass of iron in the rust and the mass of aluminum in the final sample.

Tracy Tourville

Tracy Tourville

Numerade Educator

Problem 113

Normal respiration rate of humans is $12-20$ breaths/min. When inhaling, you take in approximately $500 \mathrm{~mL}$ of air, each milliliter of which contains about $2.5 \times 10^{19} \mathrm{~mol}-$ ecules. Suppose you delivered a 10 minute speech in a class and, due to the stress you feel during that time, your respiration rate was 20 breaths/min.
(a) Calculate the number of air molecules you inhaled during your speech.
(b) There are approximately $1.1 \times 10^{44}$ air molecules in the entire atmosphere. Calculate the fraction of all air molecules in the atmosphere you inhaled during your speech.
(c) Now, well after your speech is over, take a breath. Estimate the number of molecules in that breath that also were in the air you inhaled and exhaled during your speech.

Charles Thomas

Numerade Educator

Problem 114

In April 2010 the main pipe of the Deepwater Horizon oil-drilling platform burst, spewing crude oil into the Gulf of Mexico. On April $25,2010,$ the spilled crude oil that reached the surface of the Gulf formed an oil slick $120 \mathrm{nm}$ thick covering an area of $1.5 \times 10^{3} \mathrm{~km}^{2}$. Calculate the number of barrels of crude oil in this slick; 1 barrel $=42$ gal.

Aadit Sharma

Numerade Educator

Problem 115

You and your lab partner are each given metal cubes that look similar. Your assignment is to make length and mass measurements and use only these data to determine whether the metal is the same in each cube. Your cube is $1.32 \mathrm{~cm}$ on each edge and has a mass of $16.23 \mathrm{~g}$. Your partner's cube has a mass of $24.64 \mathrm{~g}$ and each edge measures $1.46 \mathrm{~cm}$. Your partner says that the metal is the same in each cube; you don't agree. Refute your partner's conclusion.

Aadit Sharma

Numerade Educator

Problem 116

Fritz Haber, a German chemist, proposed extracting gold from seawater as a way to pay off Germany's debt, $\$ 28.8 \times 10^{6}$, after World War I. The value of gold at the time was $\$ 21.25 /$ troy oz $(1$ troy $o z=31.103 \mathrm{~g})$. The gold concentration in seawater is $0.15 \mathrm{mg}$ gold/ton seawater $(1$ ton $=2000 \mathrm{lb}$ ). Assume the density of seawater is $1.03 \mathrm{~g} / \mathrm{cm}^{3}$
(a) Calculate the volume (in cubic kilometers) of seawater that would have had to be processed to obtain the required mass of gold.
(b) By comparison, an Olympic-sized swimming pool is $50 \mathrm{~m} \times 25 \mathrm{~m} \times 2.0 \mathrm{~m} .$ Calculate the number of Olympic-sized swimming pools required to hold the volume of seawater needed in part (a).

Madi Sousa

Numerade Educator

Problem 117

Prior to 1734 , only 14 elements were known. The rest of the known elements have been discovered across the next nearly three centuries. From $1805-1825,12$ new elements were discovered. A cluster of six new elements was isolated and identified from $1895-1905 .$ Beginning in 1940 to the present, 19 new elements have been characterized. During each of these periods of discovery, a single scientific discovery or breakthrough led to the discovery of the new elements. Use the Internet to determine what each of the discoveries was and how it led to the discovery of new elements.

Stanley Enemuo

Numerade Educator

Problem 118

A group of astronauts in a spaceship accidentally encounters a space warp that traps them in an alternative universe where the chemical elements are quite different from the ones they are used to. For the elements they discovered, the astronauts found these properties:
$$
\begin{array}{crllll}
\hline \begin{array}{c}
\text { Atomic } \\
\text { Symbol }
\end{array} & \begin{array}{c}
\text { Atomic } \\
\text { Weight }
\end{array} & \text { State } & \text { Color } & \begin{array}{l}
\text { Electrical } \\
\text { Conductivity }
\end{array} & \begin{array}{l}
\text { Chemical } \\
\text { Reactivity }
\end{array} \\
\hline \text { A } & 3.2 & \text { Solid } & \text { Silvery } & \text { High } & \text { Medium } \\
\text { D } & 13.5 & \text { Gas } & \text { Colorless } & \text { Very low } & \text { Very high } \\
\text { E } & 5.31 & \text { Solid } & \text { Golden } & \text { Very high } & \text { Medium } \\
\text { G } & 15.43 & \text { Solid } & \text { Silvery } & \text { High } & \text { Medium } \\
\text { J } & 27.89 & \text { Solid } & \text { Silvery } & \text { High } & \text { Medium } \\
\text { L } & 21.57 & \text { Liquid } & \text { Colorless } & \text { Very low } & \text { Medium } \\
\text { M } & 11.23 & \text { Gas } & \text { Colorless } & \text { Very low } & \text { Very low } \\
\text { Q } & 8.97 & \text { Liquid } & \text { Colorless } & \text { Very low } & \text { Medium } \\
\text { R } & 1.02 & \text { Gas } & \text { Colorless } & \text { Very low } & \text { Very high } \\
\text { T } & 33.85 & \text { Solid } & \text { Colorless } & \text { Very low } & \text { Medium } \\
\text { X } & 23.68 & \text { Gas } & \text { Colorless } & \text { Very low } & \text { Very low } \\
\text { Z } & 36.2 & \text { Gas } & \text { Colorless } & \text { Very low } & \text { Medium } \\
\text { Ab } & 29.85 & \text { Solid } & \text { Golden } & \text { Very high } & \text { Medium } \\
\hline
\end{array}
$$
(a) Arrange these elements into a periodic table.
(b) If a new element, $\mathrm{X},$ with atomic weight 25.84 is discovered, what would its properties be? Where would it fit in the periodic table you constructed?
(c) Are there any elements that have not yet been discovered? If so, what would their properties be?

Ronald Prasad

Numerade Educator

Problem 119

You have some metal shot (small spheres like BBs), and you want to identify the metal. You have a flask that is known to contain exactly $100.0 \mathrm{~mL}$ when filled with liquid to a mark in the flask's neck. When the flask is filled with water at $20^{\circ} \mathrm{C}$, the mass of flask and water is $122.3 \mathrm{~g}$. The water is emptied from the flask and 20 of the small spheres of metal are carefully placed in the flask. The 20 small spheres had a mass of $42.3 \mathrm{~g}$. The flask is again filled to the mark with water at $20^{\circ} \mathrm{C}$ and weighed. This time the mass is $159.9 \mathrm{~g}$.
(a) What metal is in the spheres? (Assume that the spheres are all the same and consist of pure metal.)
(b) Calculate the volume occupied by 500 spheres.

Arron Martel

Numerade Educator

Problem 120

When volumes of liquids are mixed, the resulting volume is not always equal to the sum of the volume of each liquid. For example, when $50.0 \mathrm{~mL}$ of ethanol $(\mathrm{d}=$ $0.789 \mathrm{~g} / \mathrm{mL}$ ) is mixed with $50.0 \mathrm{~mL}$ of water $(0.998 \mathrm{~g} / \mathrm{mL})$ at $25^{\circ} \mathrm{C}$, the resulting volume is only $95.6 \mathrm{~mL}$. Calculate the density of the solution.

Nicole Smina

Numerade Educator

Problem 121

Consider a 1.5 in. diameter solid sphere of sterling silver, which is a uniform mixture (an alloy) of $7.5 \%$ copper and $92.5 \%$ silver, by mass. The densities of the metals are: copper $=8.96 \mathrm{~g} / \mathrm{cm}^{3} ;$ silver $=10.5 \mathrm{~g} / \mathrm{cm}^{3} .$ Calculate the mass of the sphere.

Aadit Sharma

Numerade Educator

Problem 122

The element zinc reacts with the element sulfur to form a white solid compound, zinc sulfide. When a sample of zinc that weighs $65.4 \mathrm{~g}$ reacts with sulfur, it is found that the zinc sulfide produced weighs exactly $97.5 \mathrm{~g}$.
(a) Calculate the mass of sulfur in the zinc sulfide.
(b) Calculate the mass of zinc sulfide that could be produced from $20.0 \mathrm{~g}$ zinc.

Aadit Sharma

Numerade Educator

Problem 123

The element magnesium reacts with the element oxygen to form a white solid compound, magnesium oxide. When a sample of magnesium that weighs $24.30 \mathrm{~g}$ reacts with oxygen, it is found that the magnesium oxide produced weighs exactly $40.30 \mathrm{~g}$.
(a) Calculate the mass of oxygen in the magnesium oxide.
(b) Calculate the mass of magnesium oxide that could be produced from $40.0 \mathrm{~g}$ magnesium.

Aadit Sharma

Numerade Educator

Problem 124

A chemist analyzed several portions taken from different parts of a sample that contained only iron, $\mathrm{Fe},$ and sulfur, S. She reported the results in the table. Could this sample be a compound of iron and sulfur? Explain why or why not.
$$
\begin{array}{ccc}
\hline \text { Portion } & \text { Total Mass }(g) & \text { Mass of Fe }(g) \\
\hline 1 & 1.518 & 0.964 \\
2 & 2.056 & 1.203 \\
3 & 1.873 & 1.290 \\
\hline
\end{array}
$$

Nicole Smina

Numerade Educator

Problem 125

A chemist analyzed several portions taken from different parts of a sample that contained only selenium, Se, and oxygen, $\mathrm{O}$. She reported the results in the table. Could this sample be a compound of selenium and oxygen? Explain why or why not.
$$
\begin{array}{ccc}
\hline \text { Portion } & \text { Total Mass }(g) & \text { Mass of Se }(g) \\
\hline 1 & 1.518 & 1.08 \\
2 & 2.056 & 1.46 \\
3 & 1.873 & 1.33 \\
\hline
\end{array}
$$

Nicole Smina

Numerade Educator

Problem 126

When $12.6 \mathrm{~g}$ calcium carbonate (the principal component of chalk) is treated with $63.0 \mathrm{~mL}$ hydrochloric acid (muriatic acid sold in hardware stores; density $=1.096 \mathrm{~g} / \mathrm{mL}$ ), the calcium carbonate reacts with the acid, goes into solution, and carbon dioxide gas bubbles out of the solution. After all of the carbon dioxide has escaped, the solution weighs $76.1 \mathrm{~g} .$ Calculate the volume (in liters) of carbon dioxide gas that was produced. (The density of the carbon dioxide gas is $1.798 \mathrm{~g} / \mathrm{L}$.)

Aadit Sharma

Numerade Educator

Problem 127

When $15.6 \mathrm{~g}$ sodium carbonate (washing soda used in tie dyes) is treated with $63.0 \mathrm{~mL}$ hydrochloric acid (muriatic acid sold in hardware stores; density $=1.096 \mathrm{~g} / \mathrm{mL}$ ), the sodium carbonate reacts with the acid, goes into solution, and carbon dioxide gas bubbles out of the solution. All of the carbon dioxide is collected and its volume is found to be $3.29 \mathrm{~L}$. Calculate the mass of solution that remains. (The density of the carbon dioxide gas is $1.798 \mathrm{~g} / \mathrm{L}$.)

Aadit Sharma

Numerade Educator