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Chemistry and Chemical Reactivity

John C. Kotz, Paul M. Treichel, John R. Townsend

Chapter 2

Atoms, Molecules, and Ions - all with Video Answers

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Chapter Questions

01:35

Problem 1

What are the three fundamental particles from which atoms are built? What are their electric charges? Which of these particles constitute the nucleus of an atom? Which is the least massive particle of the three?

Christy Bales, Ph.D.
Christy Bales, Ph.D.
Numerade Educator
00:22

Problem 2

Define mass number. What is the difference between mass number and atomic mass?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
View

Problem 3

An atom has a very small nucleus surrounded by an electron "cloud." Figure 2.1 represents the nucleus with a diameter of about $2 \mathrm{mm}$ and describes the electron cloud as extending over $200 \mathrm{m}$. If the diameter of an atom is $1 \times 10^{-8} \mathrm{cm},$ what is the approximate diameter of its nucleus?

Ronald Prasad
Ronald Prasad
Numerade Educator
04:03

Problem 4

A gold atom has a radius of $145 \mathrm{pm}$. If you could string gold atoms like beads on a thread, how many atoms would you need to have a necklace $36 \mathrm{cm}$ long?

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
01:16

Problem 5

Give the complete symbol $\left(_{Z}^{A} X\right),$ including atomic number and mass number, for each of the following atoms: (a) magnesium with 15 neutrons, (b) titanium with 26 neutrons, and (c) zinc with 32 neutrons.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:26

Problem 6

Give the complete symbol $\left(_{Z}^{A} \mathrm{X}\right),$ including atomic number and mass number, of (a) a nickel atom with
31 neutrons, (b) a plutonium atom with 150 neutrons, and (c) a tungsten atom with 110 neutrons.

Vasu Makani
Vasu Makani
Numerade Educator
04:20

Problem 7

How many electrons, protons, and neutrons are there in each of the following atoms?

(a) magnesium- $24,^{24} \mathrm{Mg}$
(b) $\operatorname{tin}-119,^{119} \mathrm{Sn}$
(c) thorium-232, $^{232}$ Th
(d) carbon- $13,^{13} \mathrm{C}$
(e) copper-63, $^{63} \mathrm{Cu}$
(f) bismuth- $205,205 \mathrm{Bi}$

Muhammad Bin
Muhammad Bin
Numerade Educator
01:07

Problem 8

Atomic structure.
(a) The synthetic radioactive element technetium is used in many medical studies. Give the number of electrons, protons, and neutrons in an atom of technetium-99.
(b) Radioactive americium-241 is used in household smoke detectors and in bone mineral analysis. Give the number of electrons, protons, and neutrons in an atom of americium-241.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:56

Problem 9

From cathode ray experiments, J. J. Thomson estimated that the mass of an electron was "about a thousandth" of the mass of a proton. How accurate is that estimate? Calculate the ratio of the mass of an electron to the mass of a proton.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:53

Problem 10

In 1886 Eugene Goldstein observed positively charged particles moving in the opposite direction to electrons in a cathode ray tube (illustrated below). From their mass, he concluded that these particles were formed from residual gas in the tube. For example, if the cathode ray tube contained helium, the canal rays consisted of $\mathrm{He}^{+}$ ions. Describe a process that could lead to these ions.
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:32

Problem 11

Marie Curie was born in Poland but studied and carried out her research in Paris. In $1903,$ she shared the Nobel Prize in Physics with H. Becquerel and her husband Pierre for their discovery of radioactivity. (In 1911 she received the Nobel Prize in Chemistry for the discovery of two new chemical elements, radium and polonium, the latter named for her homeland, Poland.) They and others observed that a radioactive substance could emit three types of radiation: alpha $(\alpha),$ beta $(\beta)$ and gamma ( $\gamma$ ). If the radiation from a radioactive source is passed between electrically charged plates, some particles are attached to the positive plate, some to the negative plate, and others feel no attraction. Which particles are positively charged, which are negatively charged, and which have no charge? Of the two charged particles, which has the most mass?
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:52

Problem 12

Early in the 1800 's John Dalton proposed that an atom was a "solid, massy, hard, impenetrable, moveable particle." Critique this description. How does this description misrepresent atomic structure?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:50

Problem 13

The mass of an $^{16} \mathrm{O}$ atom is 15.995 u. What is its mass relative to the mass of an atom of $^{12} \mathrm{C} ?$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
05:14

Problem 14

What is the mass of one $^{16} \mathrm{O}$ atom, in grams?

Muhammad Bin
Muhammad Bin
Numerade Educator
04:49

Problem 15

Cobalt has three radioactive isotopes used in medical studies. Atoms of these isotopes have $30,31,$ and
33 neutrons, respectively. Give the complete symbol for each of these isotopes.

Muhammad Bin
Muhammad Bin
Numerade Educator
00:44

Problem 16

Naturally occurring silver exists as two isotopes having mass numbers 107 and $109 .$ How many protons, neutrons, and electrons are there in each of these isotopes?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:31

Problem 17

Name and describe the composition of the three hydrogen isotopes.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:26

Problem 18

Which of the following are isotopes of element X, the atomic number for which is $9:_{9}^{19} \mathrm{X},_{9}^{20} \mathrm{X},_{18}^{9} \mathrm{X},$ and $_{9}^{21} \mathrm{X} ?$

Muhammad Bin
Muhammad Bin
Numerade Educator
00:22

Problem 19

Thallium has two stable isotopes, $^{203} \mathrm{Tl}$ and $^{205} \mathrm{Tl}$. Knowing that the atomic weight of thallium is 204.4 which isotope is the more abundant of the two?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:50

Problem 20

Strontium has four stable isotopes. Strontium- 84 has a very low natural abundance, but $^{86} \mathrm{Sr},^{87} \mathrm{Sr},$ and $^{88} \mathrm{Sr}$ are all reasonably abundant. Knowing that the atomic weight of strontium is $87.62,$ which of the more abundant isotopes predominates?

RS
Rajpal Sian
Numerade Educator
01:14

Problem 21

Verify that the atomic weight of lithium is $6.94,$ given the following information:
$^{6} \mathrm{Li},$ mass $=6.015121 \mathrm{u} ;$ percent abundance $=7.50 \%$
$^{7} \mathrm{Li},$ mass $=7.016003 \mathrm{u} ;$ percent abundance $=92.50 \%$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:02

Problem 22

Verify that the atomic weight of magnesium is 24.31 given the following information:
$^{24} \mathrm{Mg},$ mass $=23.985042 \mathrm{u} ;$ percent abundance $=78.99 \%$
$^{25} \mathrm{Mg},$ mass $=24.985837 \mathrm{u} ;$ percent abundance $=10.00 \%$
$^{26} \mathrm{Mg},$ mass $=25.982593 \mathrm{u} ;$ percent abundance $=11.01 \%$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:10

Problem 23

Gallium has two naturally occurring isotopes, $^{69} \mathrm{Ga}$ and $^{71} \mathrm{Ga},$ with masses of $68.9257 \mathrm{u}$ and $70.9249 \mathrm{u},$ respectively. Calculate the percent abundances of these isotopes of gallium.

David Collins
David Collins
Numerade Educator
02:18

Problem 24

Europium has two stable isotopes, $^{151} \mathrm{Eu}$ and $^{153} \mathrm{Eu}$, with masses of $150.9197 \mathrm{u}$ and $152.9212 \mathrm{u},$ respectively. Calculate the percent abundances of these isotopes of europium.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:16

Problem 25

Titanium and thallium have symbols that are easily confused with each other. Give the symbol, atomic number, atomic weight, and group and period number of each element. Are they metals, metalloids, or nonmetals?

RS
Rajpal Sian
Numerade Educator
00:59

Problem 26

In Groups $4 \mathrm{A}-6 \mathrm{A}$, there are several elements whose symbols begin with S. Name these elements, and for each one give its symbol, atomic number, group number, and period. Describe each as a metal, metalloid, or nonmetal.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:33

Problem 27

How many periods of the periodic table have 8 elements, how many have 18 elements, and how many have 32 elements?

David Collins
David Collins
Numerade Educator
00:39

Problem 28

How many elements occur in the seventh period? What is the name given to the majority of these elements, and what well-known property characterizes them?

RS
Rajpal Sian
Numerade Educator
01:20

Problem 29

Select answers to the questions listed below from the following list of elements whose symbols start with the letter $\mathrm{C}: \mathrm{C}, \mathrm{Ca}, \mathrm{Cr}, \mathrm{Co}, \mathrm{Cd}, \mathrm{Cl}, \mathrm{Cs}, \mathrm{Ce}, \mathrm{Cm}, \mathrm{Cu},$ and Cf. (You
should expect to use some symbols more than once.)
(a) Which are nonmetals?
(b) Which are main group elements?
(c) Which are lanthanides?
(d) Which are transition elements?
(e) Which are actinides?
(f) Which are gases?

David Collins
David Collins
Numerade Educator
00:38

Problem 30

Give the name and chemical symbol for the following.
(a) a nonmetal in the second period
(b) an alkali metal in the fifth period
(c) the third-period halogen
(d) an element that is a gas at $20^{\circ} \mathrm{C}$ and 1 atmosphere pressure

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:34

Problem 31

Classify the following elements as metals, metalloids, or nonmetals: $\mathrm{N}, \mathrm{Na}, \mathrm{Ni}, \mathrm{Ne},$ and $\mathrm{Np}$

David Collins
David Collins
Numerade Educator
01:08

Problem 32

Here are symbols for five of the seven elements whose names begin with the letter $\mathrm{B}: \mathrm{B}, \mathrm{Ba}, \mathrm{Bk}, \mathrm{Bi},$ and $\mathrm{Br}$
Match each symbol with one of the descriptions below.
(a) a radioactive element
(b) a liquid at room temperature
(c) a metalloid
(d) an alkaline earth element
(e) a group 5 A element

RS
Rajpal Sian
Numerade Educator
00:57

Problem 33

A model of nitric acid is illustrated here. Write the molecular formula for nitric acid, and draw the structural formula. Describe the structure of the molecule. Is it flat? That is, are all the atoms in the plane of the paper? (Color code: nitrogen atoms are blue; oxygen atoms are red; and hydrogen atoms are white.)
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:48

Problem 34

A model of the amino acid asparagine is illustrated here. Write the molecular formula for the compound, and draw its structural formula.
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:00

Problem 35

What is the charge on the common monatomic ions of the following elements?
(a) magnesium
(b) zinc
(c) nickel
(d) gallium

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:32

Problem 36

What is the charge on the common monatomic ions of the following elements?
(a) selenium
(b) fluorine
(c) iron
(d) nitrogen

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:19

Problem 37

Give the symbol, including the correct charge, for each of the following ions:
(a) barium ion
(b) titanium(IV) ion
(c) phosphate ion
(d) hydrogen carbonate ion
(e) sulfide ion
(f) perchlorate ion
(g) cobalt(II) ion
(h) sulfate ion

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
01:04

Problem 38

Give the symbol, including the correct charge, for each of the following ions:
(a) permanganate ion
(b) nitrite ion
(c) dihydrogen phosphate ion
(d) ammonium ion
(e) phosphate ion
(f) sulfite ion

Joanna Josey
Joanna Josey
Numerade Educator
01:04

Problem 39

When a potassium atom becomes a monatomic ion, how many electrons does it lose or gain? What noble gas atom has the same number of electrons as a potassium ion?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
00:33

Problem 40

When oxygen and sulfur atoms become monatomic ions, how many electrons does each lose or gain? Which noble gas atom has the same number of electrons as an oxide ion? Which noble gas atom has the same number of electrons as a sulfide ion?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:33

Problem 41

What are the charges on the ions in an ionic compound containing the elements barium and bromine? Write the formula for the compound.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:28

Problem 42

What are the charges of the ions in an ionic compound containing cobalt(III) and fluoride ions? Write the formula for the compound.

Joanna Josey
Joanna Josey
Numerade Educator
01:28

Problem 43

Give the formula and the number of each ion that makes up each of the following compounds:
(a) $\mathrm{K}_{2} \mathrm{S}$
(b) $\cos \mathrm{O}_{4}$
(c) $\mathrm{KMnO}_{4}$
(d) $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$
(e) $\mathrm{Ca}(\mathrm{ClO})_{2}$
(f) $\mathrm{NaCH}_{3} \mathrm{CO}_{2}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:31

Problem 44

Give the formula and the number of each ion that makes up each of the following compounds:
(a) $\mathrm{Mg}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}$
(b) $\mathrm{Al}(\mathrm{OH})_{3}$
(c) $\mathrm{CuCO}_{3}$
(d) $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$
(e) $\mathrm{Ca}(\mathrm{ClO})_{2}$
(f) $\mathrm{NaCH}_{3} \mathrm{CO}_{2}$

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
01:46

Problem 45

Cobalt forms $\mathrm{Co}^{2+}$ and $\mathrm{Co}^{3+}$ ions. Write the formulas for the two cobalt oxides formed by these transition metal ions.

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
01:48

Problem 46

Platinum is a transition element and forms $\mathrm{Pt}^{2+}$ and $\mathrm{Pt}^{4+}$ ions. Write the formulas for the compounds of each of these ions with (a) chloride ions and (b) sulfide ions.

Joanna Josey
Joanna Josey
Numerade Educator
00:34

Problem 47

Which of the following are correct formulas for ionic compounds? For those that are not, give the correct formula.
(a) $\mathrm{AlCl}_{2}$
(b) $\mathrm{KF}_{2}$
(c) $\mathrm{Ga}_{2} \mathrm{O}_{3}$
(d) MgS

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:34

Problem 48

Which of the following are correct formulas for ionic compounds? For those that are not, give the correct formula.
(a) $\mathrm{Ca}_{2} \mathrm{O}$
(b) $\operatorname{Sr} \mathrm{Br}_{2}$
(c) $\mathrm{Fe}_{2} \mathrm{O}_{5}$
(d) $\mathrm{Li}_{2} \mathrm{O}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:06

Problem 49

Name each of the following ionic compounds:
(a) $\mathrm{K}_{2} \mathrm{S}$
(b) $\cos \mathrm{O}_{4}$
(c) $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$
(d) $\mathrm{Ca}(\mathrm{ClO})_{2}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:39

Problem 50

Name each of the following ionic compounds:
(a) $\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2}$
(b) $\mathrm{Ni}_{3}\left(\mathrm{PO}_{4}\right)_{2}$
(c) $\mathrm{Al}(\mathrm{OH})_{3}$
(d) $\mathrm{KH}_{2} \mathrm{PO}_{4}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:07

Problem 51

Give the formula for each of the following ionic compounds:
(a) ammonium carbonate
(b) calcium iodide
(c) copper(II) bromide
(d) aluminum phosphate
(e) silver(I) acetate

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
02:26

Problem 52

Give the formula for each of the following ionic compounds:
(a) calcium hydrogen carbonate
(b) potassium permanganate
(c) magnesium perchlorate
(d) potassium hydrogen phosphate
(e) sodium sulfite

Joanna Josey
Joanna Josey
Numerade Educator
02:06

Problem 53

Write the formulas for the four ionic compounds that can be made by combining each of the cations $\mathrm{Na}^{+}$ and Ba $^{2+}$ with the anions $\mathrm{CO}_{3}^{2-}$ and $\mathrm{I}^{-} .$ Name each of the compounds.

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
02:41

Problem 54

Write the formulas for the four ionic compounds that can be made by combining the cations $\mathrm{Mg}^{2+}$ and $\mathrm{Fe}^{3+}$with the anions $\mathrm{PO}_{4}^{3-}$ and $\mathrm{NO}_{3}^{-} .$ Name each compound formed.

Joanna Josey
Joanna Josey
Numerade Educator
02:39

Problem 55

Sodium ions, $\mathrm{Na}^{+},$ form ionic compounds with fluoride ions, $\mathrm{F}^{-},$ and iodide ions, $\mathrm{I}^{-} .$ The radii of these ions are as follows: $\mathrm{Na}^{+}=116 \mathrm{pm} ; \mathrm{F}^{-}=119 \mathrm{pm} ;$ and $\mathrm{I}^{-}=$
$206 \mathrm{pm} .$ In which ionic compound, $\mathrm{NaF}$ or $\mathrm{NaI}$, are the forces of attraction between cation and anion stronger? Explain your answer.

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
02:00

Problem 56

Consider the two ionic compounds $\mathrm{NaCl}$ and $\mathrm{CaO} .$ In which compound are the cation-anion attractive forces stronger? Explain your answer.

Joanna Josey
Joanna Josey
Numerade Educator
02:38

Problem 57

Name each of the following binary, nonionic compounds:
(a) $\mathrm{NF}_{3}$
(b) $\mathrm{HI}$
(c) $\mathrm{BI}_{3}$
(d) $\mathrm{PF}_{5}$

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
02:53

Problem 58

Name each of the following binary, nonionic compounds:
(a) $\mathrm{N}_{2} \mathrm{O}_{5}$
(b) $\mathrm{P}_{4} \mathrm{S}_{3}$
(c) $\mathrm{OF}_{2}$
(d) $\mathrm{XeF}_{4}$

Joanna Josey
Joanna Josey
Numerade Educator
03:55

Problem 59

Give the formula for each of the following compounds:
(a) sulfur dichloride
(b) dinitrogen pentaoxide
(c) silicon tetrachloride
(d) diboron trioxide (commonly called boric oxide)

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
01:21

Problem 60

Give the formula for each of the following compounds:
(a) bromine trifluoride
(b) xenon difluoride
(c) hydrazine
(d) diphosphorus tetrafluoride
(e) butane

Joanna Josey
Joanna Josey
Numerade Educator
09:30

Problem 61

Calculate the mass, in grams, of each the following:
(a) 2.5 mol of aluminum $\quad$ (c) 0.015 mol of calcium
(b) $1.25 \times 10^{-3}$ mol of iron $\quad$ (d) 653 mol of neon

Muhammad Bin
Muhammad Bin
Numerade Educator
03:16

Problem 62

Calculate the mass, in grams, of each the following:
(a) 4.24 mol of gold
(b) 15.6 mol of $\mathrm{He}$
(c) 0.063 mol of platinum
(d) $3.63 \times 10^{-4}$ mol of $\mathrm{Pu}$

RS
Rajpal Sian
Numerade Educator
01:12

Problem 63

Calculate the amount (moles) represented by each of the following:
(a) $127.08 \mathrm{g}$ of $\mathrm{Cu}$
(b) 0.012 g of lithium
(c) $5.0 \mathrm{mg}$ of americium
(d) 6.75 g of $\mathrm{Al}$

David Collins
David Collins
Numerade Educator
00:59

Problem 64

Calculate the amount (moles) represented by each of the following:
(a) $16.0 \mathrm{g}$ of $\mathrm{Na}$ (b) $0.876 \mathrm{g}$ of tin
(c) 0.0034 g of platinum
(d) 0.983 g of $\mathrm{Xe}$

David Collins
David Collins
Numerade Educator
02:55

Problem 65

You are given 1.0 -g samples of He, Fe, Li, Si, and C. Which sample contains the largest number of atoms? Which contains the smallest?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:52

Problem 66

You are given 0.10 -g samples of $\mathrm{K},$ Mo, $\mathrm{Cr},$ and $\mathrm{Al}$. List the samples in order of the amount (moles), from smallest to largest.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:28

Problem 67

Analysis of a 10.0 -g sample of apatite (a major component of tooth enamel) showed that it was made up of $3.99 \mathrm{g} \mathrm{Ca}, 1.85 \mathrm{g} \mathrm{P}, 4.14 \mathrm{g} \mathrm{O},$ and $0.020 \mathrm{g} \mathrm{H} .$ List these
elements based on relative amounts (moles), from smallest to largest.

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
01:03

Problem 68

A semiconducting material is composed of 52 g of Ga, $9.5 \mathrm{g}$ of $\mathrm{Al},$ and $112 \mathrm{g}$ of As. Which element has the largest number of atoms in this material?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:19

Problem 69

Calculate the molar mass of each of the following compounds:
(a) $\mathrm{Fe}_{2} \mathrm{O}_{3},$ iron(III) oxide
(b) $\mathrm{BCl}_{3},$ boron trichloride
(c) $\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6},$ ascorbic acid (vitamin
C)

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
05:47

Problem 70

Calculate the molar mass of each of the following compounds:
(a) $\mathrm{Fe}\left(\mathrm{C}_{6} \mathrm{H}_{11} \mathrm{O}_{7}\right)_{2},$ iron (II) gluconate, a dietary supplement
(b) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{SH},$ butanethiol, has a skunk-like
odor
(c) $\mathrm{C}_{20} \mathrm{H}_{24} \mathrm{N}_{2} \mathrm{O}_{2},$ quinine, used as an antimalarial drug

Marjanii Walton
Marjanii Walton
Numerade Educator
08:13

Problem 71

Calculate the molar mass of each hydrated compound. Note that the water of hydration is included in the molar mass. (See page 82.)
(a) $\mathrm{Ni}\left(\mathrm{NO}_{3}\right)_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$
(b) $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$

Muhammad Bin
Muhammad Bin
Numerade Educator
06:08

Problem 72

Calculate the molar mass of each hydrated compound. Note that the water of hydration is included in the molar mass. (See page 82.)
(a) $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}$
(b) $\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O},$ Epsom salt

Muhammad Bin
Muhammad Bin
Numerade Educator
02:36

Problem 73

What mass is represented by 0.0255 mol of each of the following compounds?
(a) $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH},$ 2-propanol, rubbing alcohol
(b) $\mathrm{C}_{11} \mathrm{H}_{16} \mathrm{O}_{2},$ an antioxidant in foods, also known as BHA (butylated hydroxyanisole)
(c) $\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4},$ aspirin
(d) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CO},$ acetone, an important industrial solvent

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:10

Problem 74

Assume you have 0.123 mol of each of the following compounds. What mass of each is present?
(a) $\mathrm{C}_{14} \mathrm{H}_{10} \mathrm{O}_{4},$ benzoyl peroxide, used in acne medications
(b) Dimethylglyoxime, used in the laboratory to test for nickel(II) ions
(EQUATION CAN'T COPY)
(c) The compound below, responsible for the "skunky" taste in poorly made beer.
(EQUATION CAN'T COPY)
(d) DEET, a mosquito repellent
(EQUATION CAN'T COPY)

Prashant Bana
Prashant Bana
Numerade Educator
06:05

Problem 75

Sulfur trioxide, $\mathrm{SO}_{3}$, is made industrially in enormous quantities by combining oxygen and sulfur dioxide, SO $_{2} .$ What amount (moles) of $\mathrm{SO}_{3}$ is represented by 1.00 kg of sulfur trioxide? How many molecules? How many sulfur atoms? How many oxygen atoms?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
04:19

Problem 76

How many ammonium ions and how many sulfate ions are present in a 0.20 mol sample of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} ?$ How many atoms of $\mathrm{N}, \mathrm{H}, \mathrm{S}$ and $\mathrm{O}$ are contained in this sample?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
05:08

Problem 77

Acetaminophen, whose structure is drawn below, is the active ingredient in some nonprescription pain killers. The recommended dose for an adult is two 500 mg caplets. How many molecules make up one dose of this drug?
(FIGURE CAN'T COPY)

Muhammad Bin
Muhammad Bin
Numerade Educator
06:43

Problem 78

An Alka-Seltzer tablet contains 324 mg of aspirin $\left(\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}\right), 1904 \mathrm{mg}$ of $\mathrm{NaHCO}_{3},$ and $1000 .$ mg of citric
acid $\left(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right) .$ (The last two compounds react with each other to provide the "fizz," bubbles of $\mathrm{CO}_{2},$ when the tablet is put into water.)
(a) Calculate the amount (moles) of each substance in the tablet.
(b) If you take one tablet, how many molecules of aspirin are you consuming?

Joanna Josey
Joanna Josey
Numerade Educator
07:55

Problem 79

Calculate the mass percent of each element in the following compounds:
(a) PbS, lead(II) sulfide, galena
(b) $\mathrm{C}_{3} \mathrm{H}_{8},$ propane
(c) $\mathrm{C}_{10} \mathrm{H}_{14} \mathrm{O},$ carvone, found in caraway seed oil

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
07:08

Problem 80

Calculate the mass percent of each element in the following compounds:
(a) $\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{N}_{2} \mathrm{O}_{2},$ caffeine
(b) $\mathrm{C}_{10} \mathrm{H}_{20} \mathrm{O},$ menthol
(c) $\mathrm{CoCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$

Joanna Josey
Joanna Josey
Numerade Educator
02:08

Problem 81

Calculate the mass percent of copper in CuS, copper(II) sulfide. If you wish to obtain $10.0 \mathrm{g}$ of copper metal from copper(II) sulfide, what mass of CuS (in grams) must you use?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:34

Problem 82

Calculate the mass percent of titanium in the mineral ilmenite, FeTiO $_{3} .$ What mass of ilmenite (in grams) is required if you wish to obtain 750 g of titanium?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:37

Problem 83

Succinic acid occurs in fungi and lichens. Its empirical formula is $\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2},$ and its molar mass is $118.1 \mathrm{g} / \mathrm{mol} .$
What is its molecular formula?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
03:01

Problem 84

An organic compound has the empirical formula $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{NO} .$ If its molar mass is $116.1 \mathrm{g} / \mathrm{mol},$ what is the
molecular formula of the compound?

Joanna Josey
Joanna Josey
Numerade Educator
00:56

Problem 85

Complete the following table:
(TABLE CAN'T COPY)

John Connell
John Connell
Numerade Educator
00:56

Problem 86

Complete the following table:
(TABLE CAN'T COPY)

John Connell
John Connell
Numerade Educator
03:54

Problem 87

Acetylene is a colorless gas used as a fuel in welding torches, among other things. It is $92.26 \%$ C and $7.74 \%$
H. Its molar mass is $26.02 \mathrm{g} / \mathrm{mol} .$ What are the empirical and molecular formulas of acetylene?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
01:56

Problem 88

A large family of boron-hydrogen compounds has the general formula $\mathrm{B}_{x} \mathrm{H}_{y} .$ One member of this family contains $88.5 \%$ B; the remainder is hydrogen. What is its empirical formula?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:54

Problem 89

Cumene, a hydrocarbon, is a compound composed only of $\mathrm{C}$ and $\mathrm{H}$. It is $89.94 \%$ carbon, and its molar mass is $120.2 \mathrm{g} / \mathrm{mol} .$ What are the empirical and molecular formulas of cumene?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
02:51

Problem 90

In $2006,$ a Russian team discovered an interesting molecule they called "sulflower" because of its shape and because it was based on sulfur. It is composed of $57.17 \% \mathrm{S}$ and $42.83 \%$ C and has a molar mass of $448.70 \mathrm{g} / \mathrm{mol} .$ Determine the empirical and molecular formulas of "sulflower."

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:51

Problem 91

Mandelic acid is an organic acid composed of carbon $(63.15 \%),$ hydrogen $(5.30 \%),$ and oxygen $(31.55 \%) .$ Its molar mass is $152.14 \mathrm{g} / \mathrm{mol} .$ Determine the empirical and molecular formulas of the acid.

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
06:04

Problem 92

Nicotine, a poisonous compound found in tobacco leaves, is $74.0 \% \mathrm{C}, 8.65 \% \mathrm{H},$ and $17.35 \% \mathrm{N} .$ Its molar mass is 162 g/mol. What are the empirical and molecular formulas of nicotine?

Joanna Josey
Joanna Josey
Numerade Educator
02:03

Problem 93

A compound containing xenon and fluorine was prepared by shining sunlight on a mixture of $\mathrm{Xe}(0.526 \mathrm{g})$ and excess $\mathrm{F}_{2}$ gas. If you isolate $0.678 \mathrm{g}$ of the new compound, what is its empirical formula?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:45

Problem 94

Elemental sulfur $(1.256 \mathrm{g})$ is combined with fluorine, $\mathrm{F}_{2},$ to give a compound with the formula $\mathrm{SF}_{x},$ a very stable, colorless gas. If you have isolated 5.722 g of $\mathrm{SF}_{x}$, what is the value of $x ?$

Joanna Josey
Joanna Josey
Numerade Educator
View

Problem 95

Epsom salt is used in tanning leather and in medicine. It is hydrated magnesium sulfate, $\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}$. The water of hydration is lost on heating, with the number lost depending on the temperature. Suppose you heat a 1.394 -g sample at $100^{\circ} \mathrm{C}$ and obtain $0.885 \mathrm{g}$ of a partially hydrated sample, $\mathrm{MgSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}$. What is the value of $x ?$

Ronald Prasad
Ronald Prasad
Numerade Educator
01:48

Problem 96

You combine $1.25 \mathrm{g}$ of germanium, Ge, with excess chlorine, $\mathrm{Cl}_{2}$. The mass of product, $\mathrm{Ge}_{x} \mathrm{Cl}_{y},$ is $3.69 \mathrm{g} .$ What is the formula of the product, $\mathrm{Ge}_{x} \mathrm{Cl}_{y} ?$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
View

Problem 97

Fill in the blanks in the table (one column per element).
(TABLE CAN'T COPY)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
00:41

Problem 98

Potassium has three naturally occurring isotopes $\left(^{39} \mathrm{K}\right.$ $\left.^{40} \mathrm{K}, \text { and }^{41} \mathrm{K}\right),$ but $^{40} \mathrm{K}$ has a very low natural abundance. Which of the other two isotopes is more abundant? Briefly explain your answer.

David Collins
David Collins
Numerade Educator
02:43

Problem 99

Crossword Puzzle: In the $2 \times 2$ box shown here, each answer must be correct four ways: horizontally, vertically, diagonally, and by itself. Instead of words, use symbols of elements. When the puzzle is complete, the four spaces will contain the overlapping symbols of 10 elements. There is only one correct solution.
(TABLE CAN'T COPY)

Horizontal
1-2: two-letter symbol for a metal used in ancient times
$3-4:$ two-letter symbol for a metal that burns in air and is found in Group $5 \mathrm{A}$
Vertical
$1-3:$ two-letter symbol for a metalloid
2-4: two-letter symbol for a metal used in U.S. coins
single squares: All one-letter symbols
1: a colorful nonmetal
2: colorless, gaseous nonmetal
3: an element that makes fireworks green
4: an element that has medicinal uses
Diagonal
1-4: two-letter symbol for an element used in electronics
2-3: two-letter symbol for a metal used with Zr to make wires for superconducting magnets

Ronald Prasad
Ronald Prasad
Numerade Educator
00:41

Problem 100

The chart below shows a general decline in abundance with increasing mass among the first 30 elements. The decline continues beyond zinc. (Notice that the scale on the vertical axis is logarithmic, that is, it progresses in powers of $10 .$ The abundance of nitrogen, for example, is $1 / 10,000\left(1 / 10^{4}\right)$ of the abundance of hydrogen. All abundances are plotted as the number of atoms per $10^{12}$ atoms of $\mathrm{H}$. (The fact that the abundances of $\mathrm{Li}$, Be, and $\mathrm{B}$, as well as those of the elements near $\mathrm{Fe}, \mathrm{do}$ not follow the general decline is a consequence of the way that elements are synthesized in stars.)
(BAR GRAPH CAN'T COPY)
(a) What is the most abundant main group metal?
(b) What is the most abundant nonmetal?
(c) What is the most abundant metalloid?
(d) Which of the transition elements is most abundant?
(e) Which halogens are included on this plot, and which is the most abundant?

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
07:49

Problem 101

Copper atoms.
(a) What is the average mass of one copper atom?
(b) Students in a college computer science class once sued the college because they were asked to calculate the cost of one atom and could not do it. But you are in a chemistry course, and you can do this. (See E. Felsenthal, Wall Street Journal, May 9 ,
1995.) If the cost of 2.0-mm diameter copper wire $(99.999 \% \text { pure })$ is currently $\$ 41.70$ for $7.0 \mathrm{g},$ what is the cost of one copper atom?

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
01:27

Problem 102

Which of the following is impossible?
(a) silver foil that is $1.2 \times 10^{-4} \mathrm{m}$ thick
(b) a sample of potassium that contains $1.784 \times 10^{24}$ atoms
(c) a gold coin of mass $1.23 \times 10^{-3} \mathrm{kg}$
(d) $3.43 \times 10^{-27}$ mol of $\mathrm{S}_{8}$ molecules

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:42

Problem 103

Reviewing the periodic table.
(a) Name the element in Group $2 \mathrm{A}$ and the fifth period.
(b) Name the element in the fifth period and Group $4 B$.
(c) Which element is in the second period in Group $4 \mathrm{A} ?$
(d) Which element is in the fourth period in Group $5 \mathrm{A} ?$
(e) Which halogen is in the fifth period?
(f) Which alkaline earth element is in the third period?
(g) Which noble gas element is in the fourth period?
(h) Name the nonmetal in Group $6 \mathrm{A}$ and the third period.
(i) Name a metalloid in the fourth period.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:58

Problem 104

Identify two nonmetallic elements that have allotropes and describe the allotropes of each.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:52

Problem 105

In each case, decide which represents more mass:
(a) 0.5 mol of $\mathrm{Na}, 0.5$ mol of $\mathrm{Si}$, or 0.25 mol of $\mathrm{U}$
(b) $9.0 \mathrm{g}$ of $\mathrm{Na}, 0.50$ mol of $\mathrm{Na},$ or $1.2 \times 10^{22}$ atoms of Na
(c) 10 atoms of Fe or 10 atoms of $\mathrm{K}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:06

Problem 106

The recommended daily allowance (RDA) of iron for women $19-30$ years old is 18 mg. How many moles is this? How many atoms?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:27

Problem 107

Put the following elements in order from smallest to largest mass:
(a) $3.79 \times 10^{24}$ atoms Fe
(b) $19.921 \mathrm{mol} \mathrm{H}_{2}$
(c) 8.576 mol $C$
(d) $7.4 \mathrm{mol} \mathrm{Si}$
(e) 9.221 mol $\mathrm{Na}$
(f) $4.07 \times 10^{24}$ atoms Al
(g) 9.2 mol $\mathrm{Cl}_{2}$

Muhammad Bin
Muhammad Bin
Numerade Educator
02:59

Problem 108

When a sample of phosphorus burns in air, the compound $\mathrm{P}_{4} \mathrm{O}_{10}$ forms. One experiment showed that $0.744 \mathrm{g}$ of phosphorus formed $1.704 \mathrm{g}$ of $\mathrm{P}_{4} \mathrm{O}_{10} .$ Use this information to determine the ratio of the atomic weights of phosphorus and oxygen (mass P/mass O). If the atomic weight of oxygen is assumed to be 16.000 calculate the atomic weight of phosphorus.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
06:14

Problem 109

Although carbon-12 is now used as the standard for atomic weights, this has not always been the case. Early attempts at classification used hydrogen as the standard, with the weight of hydrogen being set equal to $1.0000 .$ Later attempts defined atomic weights using oxygen (with a weight of 16.0000 ). In each instance, the atomic weights of the other elements were defined relative to these masses. (To answer this question, you need more precise data on current atomic weights:
$\mathrm{H}, 1.00794 ; \mathrm{O}, 15.9994 .)$
(a) If $\mathrm{H}=1.0000$ u was used as a standard for atomic weights, what would the atomic weight of oxygen be? What would be the value of Avogadro's number under these circumstances?
(b) Assuming the standard is $\mathrm{O}=16.0000,$ determine the value for the atomic weight of hydrogen and the value of Avogadro's number.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:16

Problem 110

A reagent occasionally used in chemical synthesis is sodium-potassium alloy. (Alloys are mixtures of metals, and Na-K has the interesting property that it is a liquid.) One formulation of the alloy (the one that melts at the lowest temperature) contains 68 atom percent $\mathrm{K} ;$ that is, out of every 100 atoms, 68 are $\mathrm{K}$ and 32 are $\mathrm{Na}$. What is the mass percent of potassium in sodium-potassium alloy?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:18

Problem 111

Write formulas for all of the compounds that can be made by combining the cations $\mathrm{NH}_{4}^{+}$ and $\mathrm{Ni}^{2+}$ with the anions $\mathrm{CO}_{3}^{2-}$ and $\mathrm{SO}_{4}^{2-}$

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
02:21

Problem 112

How many electrons are in a strontium atom $(\mathrm{Sr})$ ? Does an atom of Sr gain or lose electrons when forming an ion? How many electrons are gained or lost by the atom? When Sr forms an ion, the ion has the same number of electrons as which one of the noble gases?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
00:51

Problem 113

Which of the following compounds has the highest mass percent of chlorine?
(a) $\mathrm{BCl}_{3}$
(b) $\mathrm{As} \mathrm{Cl}_{3}$
(c) $\mathrm{GaCl}_{3}$
(d) $\mathrm{AlCl}_{3}$
(e) $\mathrm{PCl}_{3}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:03

Problem 114

Which of the following samples has the largest number of ions?
(a) $1.0 \mathrm{g}$ of $\mathrm{BeCl}_{2}$
(b) $1.0 \mathrm{g}$ of $\mathrm{MgCl}_{2}$
(c) $1.0 \mathrm{g}$ of $\mathrm{CaS}$
(d) $1.0 \mathrm{g}$ of $\mathrm{SrCO}_{3}$
(e) $1.0 \mathrm{g}$ of $\mathrm{BaSO}_{4}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:59

Problem 115

The structure of one of the bases in DNA, adenine, is shown here. Which represents the greater mass: $40.0 \mathrm{g}$ of adenine or $3.0 \times 10^{23}$ molecules of the compound?
(FIGURE CAN'T COPY)

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
00:55

Problem 116

Ionic and molecular compounds of the halogens.
(a) What are the names of $\mathrm{BaF}_{2}, \mathrm{SiCl}_{4},$ and $\mathrm{NiBr}_{2} ?$
(b) Which of the compounds in part (a) are ionic, and which are molecular?
(c) Which has the largest mass, 0.50 mol of $\mathrm{Ba} \mathrm{F}_{2}$
0.50 mol of $\mathrm{SiCl}_{4},$ or 1.0 mol of $\mathrm{NiBr}_{2} ?$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:28

Problem 117

A drop of water has a volume of about $0.050 \mathrm{mL} .$ How many molecules of water are in a drop of water? (Assume water has a density of $1.00 \mathrm{g} / \mathrm{cm}^{3} .$ )

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:12

Problem 118

Capsaicin, the compound that gives the hot taste to chili peppers, has the formula $\mathrm{C}_{18} \mathrm{H}_{27} \mathrm{NO}_{3}$
(a) Calculate its molar mass.
(b) If you eat 55 mg of capsaicin, what amount (moles) have you consumed?
(c) Calculate the mass percent of each element in the compound.
(d) What mass of carbon (in milligrams) is there in
$55 \mathrm{mg}$ of capsaicin?

Joanna Josey
Joanna Josey
Numerade Educator
05:22

Problem 119

Calculate the molar mass and the mass percent of each element in the blue solid compound $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{SO}_{4} \cdot \mathrm{H}_{2} \mathrm{O} .$ What is the mass of copper and
the mass of water in $10.5 \mathrm{g}$ of the compound?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:32

Problem 120

Write the molecular formula and calculate the molar mass for each of the molecules shown here. Which has the largest mass percent of carbon? Of oxygen?
(a) ethylene glycol (used in antifreeze)
(FIGURE CAN'T COPY)
(b) dihydroxyacetone (used in artificial tanning lotions)
(FIGURE CAN'T COPY)
(c) ascorbic acid, commonly known as vitamin $C$
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:39

Problem 121

Malic acid, an organic acid found in apples, contains $C$
$\mathrm{H},$ and $\mathrm{O}$ in the following ratios: $\mathrm{C}_{1} \mathrm{H}_{1.50} \mathrm{O}_{1.25} .$ What is the empirical formula of malic acid?

Muhammad Bin
Muhammad Bin
Numerade Educator
08:19

Problem 122

Your doctor has diagnosed you as being anemic-that is, as having too little iron in your blood. At the drugstore, you find two iron-containing dietary supplements: one with iron(II) sulfate, $\mathrm{FeSO}_{4},$ and the other with iron(II) gluconate, $\mathrm{Fe}\left(\mathrm{C}_{6} \mathrm{H}_{11} \mathrm{O}_{7}\right)_{2} .$ If you take $100 .$ mg of each compound, which will deliver more atoms of iron?

Muhammad Bin
Muhammad Bin
Numerade Educator
03:42

Problem 123

A compound composed of iron and carbon monoxide, $\mathrm{Fe}_{x}(\mathrm{CO})_{y},$ is $30.70 \%$ iron. What is the empirical formula for the compound?

Joanna Josey
Joanna Josey
Numerade Educator
03:09

Problem 124

Ma huang, an extract from the ephedra species of plants, contains ephedrine. The Chinese have used this herb for more than 5000 years to treat asthma. More recently, ephedrine has been used in diet pills that can be purchased over the counter in herbal medicine shops. However, very serious concerns have been raised regarding these pills following reports that their use led to serious heart problems.
(a) A molecular model of ephedrine is drawn below. From this determine the molecular formula for ephedrine and calculate its molar mass.
(b) What is the weight percent of carbon in ephedrine?
(c) Calculate the amount (moles) of ephedrine in a $0.125 \mathrm{g}$ sample.
(d) How many molecules of ephedrine are there in $0.125 \mathrm{g} ?$ How many C atoms?
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:20

Problem 125

Saccharin, a molecular model of which is shown below, is more than 300 times sweeter than sugar. It was first made in $1897,$ when it was common practice for chemists to record the taste of any new substances they synthesized.
(a) Write the molecular formula for the compound, and draw its structural formula. (S atoms are yellow.)
(b) If you ingest 125 mg of saccharin, what amount (moles) of saccharin have you ingested?
(c) What mass of sulfur is contained in 125 mg of saccharin?
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:39

Problem 126

Name each of the following compounds and indicate which ones are best described as ionic:
(a) $\mathrm{ClF}_{3}$
(b) $\mathrm{NCl}_{3}$
(c) $\mathrm{SrSO}_{4}$
(d) $\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$
(e) $\mathrm{XeF}_{4}$
(f) $\mathrm{OF}_{2}$
(g) $\mathrm{KI}$ (h) $\mathrm{Al}_{2} \mathrm{S}_{3}$
(i) $\mathrm{PCl}_{3}$
(j) $\quad \mathrm{K}_{3} \mathrm{PO}_{4}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
11:30

Problem 127

Write the formula for each of the following compounds and indicate which ones are best described as ionic:
(a) sodium hypochlorite
(b) boron triiodide
(c) aluminum perchlorate
(d) calcium acetate
(e) potassium permanganate
(f) ammonium sulfite
(g) potassium dihydrogen phosphate
(h) disulfur dichloride
(i) chlorine trifluoride
(i) phosphorus trifluoride

Muhammad Bin
Muhammad Bin
Numerade Educator
02:52

Problem 128

Complete the table by placing symbols, formulas, and names in the blanks.
(TABLE CAN'T COPY)

Joanna Josey
Joanna Josey
Numerade Educator
07:23

Problem 129

Empirical and molecular formulas.
(a) Fluorocarbonyl hypofluorite is composed of $14.6 \% \mathrm{C}, 39.0 \%$ O, and $46.3 \%$ F. The molar mass of the compound is $82 \mathrm{g} / \mathrm{mol}$. Determine the empirical and molecular formulas of the compound.
(b) Azulene, a beautiful blue hydrocarbon, is $93.71 \% \mathrm{C}$ and has a molar mass of $128.16 \mathrm{g} / \mathrm{mol} .$ What are the empirical and molecular formulas of azulene?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
05:02

Problem 130

Cacodyl, a compound containing arsenic, was reported in 1842 by the German chemist Robert Wilhelm Bunsen. It has an almost intolerable garlic-like odor. Its molar mass is $210 \mathrm{g} / \mathrm{mol},$ and it is $22.88 \% \mathrm{C}, 5.76 \% \mathrm{H}$
and $71.36 \%$ As. Determine its empirical and molecular formulas.

Joanna Josey
Joanna Josey
Numerade Educator
04:32

Problem 131

The action of bacteria on meat and fish produces a compound called cadaverine. As its name and origin imply, it stinks! (It is also present in bad breath and adds to the odor of urine.) It is $58.77 \% \mathrm{C}, 13.81 \% \mathrm{H}$ and $27.40 \%$ N. Its molar mass is $102.2 \mathrm{g} / \mathrm{mol} .$ Determine the molecular formula of cadaverine.

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
02:17

Problem 132

In the laboratory you combine 0.125 g of nickel with CO and isolate $0.364 \mathrm{g}$ of $\mathrm{Ni}(\mathrm{CO})_{x} .$ What is the value of $x ?$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
02:56

Problem 133

A compound called MMT was once used to boost the octane rating of gasoline. What is the empirical formula of MMT if it is $49.5 \%$ C, $3.2 \% \mathrm{H}, 22.0 \%$ O, and $25.2 \%$ Mn?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:19

Problem 134

Elemental phosphorus is made by heating calcium phosphate with carbon and sand in an electric furnace. What is the mass percent of phosphorus in calcium phosphate? Use this value to calculate the mass of calcium phosphate (in kilograms) that must be used to produce $15.0 \mathrm{kg}$ of phosphorus.

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
02:16

Problem 135

Chromium is obtained by heating chromium(III) oxide with carbon. Calculate the mass percent of chromium in the oxide, and then use this value to calculate the quantity of $\mathrm{Cr}_{2} \mathrm{O}_{3}$ required to produce $850 \mathrm{kg}$ of chromium metal.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:57

Problem 136

Stibnite, $\mathrm{Sb}_{2} \mathrm{S}_{3},$ is a dark gray mineral from which antimony metal is obtained. What is the mass percent of antimony in the sulfide? If you have $1.00 \mathrm{kg}$ of an ore that contains $10.6 \%$ antimony, what mass of $\mathrm{Sb}_{2} \mathrm{S}_{3}$ (in grams) is in the ore?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:15

Problem 137

A Direct reaction of iodine $\left(\mathrm{I}_{2}\right)$ and chlorine $\left(\mathrm{Cl}_{2}\right)$ produces an iodine chloride, $\mathrm{I}_{x} \mathrm{Cl}_{y},$ a bright yellow solid. If you completely consume $0.678 \mathrm{g}$ of $\mathrm{I}_{2}$ in a reaction with excess $\mathrm{Cl}_{2}$ and produce $1.246 \mathrm{g}$ of $\mathrm{I}_{x} \mathrm{Cl}_{y},$ what is the empirical formula of the compound? A later experiment showed that the molar mass of $\mathrm{I}_{x} \mathrm{Cl}_{y}$ was $467 \mathrm{g} / \mathrm{mol}$. What is the molecular formula of the compound?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
01:54

Problem 138

In a reaction, $2.04 \mathrm{g}$ of vanadium combined with 1.93 g of sulfur to give a pure compound. What is the empirical formula of the product?

Joanna Josey
Joanna Josey
Numerade Educator
04:21

Problem 139

Iron pyrite, often called "fool's gold," has the formula FeS$_{2}$. If you could convert $15.8 \mathrm{kg}$ of iron pyrite to iron metal, what mass of the metal would you obtain?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
04:00

Problem 140

Which of the following statements about $57.1 \mathrm{g}$ of octane, $\mathrm{C}_{8} \mathrm{H}_{18},$ is (are) not true?
(a) $57.1 \mathrm{g}$ is 0.500 mol of octane.
(b) The compound is $84.1 \%$ C by weight.
(c) The empirical formula of the compound is $\mathrm{C}_{4} \mathrm{H}_{9}$
(d) $57.1 \mathrm{g}$ of octane contains $28.0 \mathrm{g}$ of hydrogen atoms.

Joanna Josey
Joanna Josey
Numerade Educator
02:36

Problem 141

The formula of barium molybdate is $\mathrm{BaMoO}_{4} .$ Which of the following is the formula of sodium molybdate?
(a) $\mathrm{Na}_{4} \mathrm{MoO}$
(b) NaMoO
(c) $\mathrm{Na}_{2} \mathrm{MoO}_{3}$
(d) $\mathrm{Na}_{2} \mathrm{MoO}_{4}$
(e) $\mathrm{Na}_{4} \mathrm{MoO}_{4}$

Muhammad Bin
Muhammad Bin
Numerade Educator
02:21

Problem 142

A metal M forms a compound with the formula $\mathrm {MCl}_{4}$. If the compound is $74.75 \%$ chlorine, what is the identity of M?

Lijeesh Krishnan
Lijeesh Krishnan
Numerade Educator
03:29

Problem 143

Pepto-Bismol, which can help provide relief for an upset stomach, contains $300 .$ mg of bismuth subsalicylate, $\mathrm{C}_{21} \mathrm{H}_{15} \mathrm{Bi}_{3} \mathrm{O}_{12},$ per tablet. If you take two tablets for
your stomach distress, what amount (in moles) of the "active ingredient" are you taking? What mass of Bi are you consuming in two tablets?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:20

Problem 144

The weight percent of oxygen in an oxide that has the formula $\mathrm{MO}_{2}$ is $15.2 \% .$ What is the molar mass of this compound? What element or elements are possible for M?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
05:32

Problem 145

The mass of 2.50 mol of a compound with the formula $\mathrm{ECl}_{4},$ in which $\mathrm{E}$ is a nonmetallic element, is $385 \mathrm{g} .$ What is the molar mass of $\mathrm{ECl}_{4} ?$ What is the identity of $\mathrm{E} ?$

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
04:15

Problem 146

The elements $A$ and $Z$ combine to produce two different compounds: $\mathrm{A}_{2} \mathrm{Z}_{3}$ and $\mathrm{AZ}_{2} .$ If 0.15 mol of $\mathrm{A}_{2} \mathrm{Z}_{3}$ has a mass of $15.9 \mathrm{g}$ and 0.15 mol of $\mathrm{AZ}_{2}$ has a mass of $9.3 \mathrm{g},$ what are the atomic weights of $\mathrm{A}$ and $\mathrm{Z?}$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
06:16

Problem 147

A Polystyrene can be prepared by heating styrene with tribromobenzoyl peroxide in the absence of air. A sample prepared by this method has the empirical formula $\mathrm{Br}_{3} \mathrm{C}_{6} \mathrm{H}_{3}\left(\mathrm{C}_{8} \mathrm{H}_{8}\right)_{n},$ where the value of $n$ can vary from sample to sample. If one sample has $0.105 \%$ Br, what is the value of $n ?$

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:47

Problem 148

A sample of hemoglobin is found to be $0.335 \%$ iron. What is the molar mass of hemoglobin if there are four iron atoms per molecule?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:12

Problem 149

A Consider an atom of $^{64} \mathrm{Zn}$
(a) Calculate the density of the nucleus in grams per cubic centimeter, knowing that the nuclear radius is $4.8 \times 10^{-6} \mathrm{nm}$ and the mass of the $64 \mathrm{Zn}$ atom is $1.06 \times 10^{-22} \mathrm{g} .$ (Recall that the volume of a sphere is $\left.[4 / 3] \pi r^{3} .\right)$
(b) Calculate the density of the space occupied by the electrons in the zinc atom, given that the atomic radius is $0.125 \mathrm{nm}$ and the electron mass is $9.11 \times$ $10^{-28} \mathrm{g}$
(c) Having calculated these densities, what statement can you make about the relative densities of the parts of the atom?

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:40

Problem 150

Estimating the radius of a lead atom.
(a) You are given a cube of lead that is $1.000 \mathrm{cm}$ on each side. The density of lead is $11.35 \mathrm{g} / \mathrm{cm}^{3} .$ How many atoms of lead are in the sample?
(b) Atoms are spherical; therefore, the lead atoms in this sample cannot fill all the available space. As an approximation, assume that $60 \%$ of the space of the cube is filled with spherical lead atoms. Calculate the volume of one lead atom from this information. From the calculated volume (V) and the formula $(4 / 3) \pi r^{3}$ for the volume of a sphere, estimate the radius ( $r$ ) of a lead atom.

Carlene Jimenez
Carlene Jimenez
Numerade Educator
10:27

Problem 151

A piece of nickel foil, $0.550 \mathrm{mm}$ thick and $1.25 \mathrm{cm}$ square, is allowed to react with fluorine, $\mathrm{F}_{2},$ to give a nickel fluoride.
(a) How many moles of nickel foil were used? (The density of nickel is $8.902 \mathrm{g} / \mathrm{cm}^{3} .$ )
(b) If you isolate $1.261 \mathrm{g}$ of the nickel fluoride, what is its formula?
(c) What is its complete name?

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
05:30

Problem 152

A Uranium is used as a fuel, primarily in the form of uranium(IV) oxide, in nuclear power plants. This question considers some uranium chemistry.
(a) $\mathrm{A}$ small sample of uranium metal $(0.169 \mathrm{g})$ is heated to between 800 and $900^{\circ} \mathrm{C}$ in air to give $0.199 \mathrm{g}$ of a dark green oxide, $\mathrm{U}_{x} \mathrm{O}_{y} .$ How many moles of uranium metal were used? What is the empirical formula of the oxide, $\mathrm{U}_{x} \mathrm{O}_{y} ?$ What is the name of the oxide? How many moles of $\mathrm{U}_{x} \mathrm{O}_{y}$ must have been obtained?
(b) The naturally occurring isotopes of uranium are $^{234} \mathrm{U},^{235} \mathrm{U},$ and $^{238} \mathrm{U} .$ Knowing that uranium's atomic weight is $238.02 \mathrm{g} / \mathrm{mol},$ which isotope must be the most abundant?
(c) If the hydrated compound $\mathrm{UO}_{2}\left(\mathrm{NO}_{3}\right)_{2} \cdot z \mathrm{H}_{2} \mathrm{O}$ is
heated gently, the water of hydration is lost. If you have $0.865 \mathrm{g}$ of the hydrated compound and obtain $0.679 \mathrm{g}$ of $\mathrm{UO}_{2}\left(\mathrm{NO}_{3}\right)_{2}$ on heating, how many
waters of hydration are in each formula unit of the original compound? (The oxide $\mathrm{U}_{x} \mathrm{O}_{y}$ is obtained if the hydrate is heated to temperatures over $800^{\circ} \mathrm{C}$ in the air.)

Maryam Shahid
Maryam Shahid
Numerade Educator
02:05

Problem 153

In an experiment, you need 0.125 mol of sodium metal. Sodium can be cut easily with a knife (Figure $2.6),$ so if you cut out a block of sodium, what should the volume of the block be in cubic centimeters? If you cut a perfect cube, what is the length of the edge of the cube? (The density of sodium is $0.97 \mathrm{g} / \mathrm{cm}^{3} .$ )
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
04:28

Problem 154

Mass spectrometric analysis showed that there are four isotopes of an unknown element having the following masses and abundances:
$$\begin{aligned}
&\\
&\begin{array}{cccc}
\text { Isotope } & \text { Mass Number } & \text { Isotope Mass } & \text { Abundance (\%) } \\
\hline 1 & 136 & 135.9090 & 0.193 \\
2 & 138 & 137.9057 & 0.250 \\
3 & 140 & 139.9053 & 88.48 \\
4 & 142 & 141.9090 & 11.07 \\
\hline
\end{array}
\end{aligned}$$
Three elements in the periodic table that have atomic weights near these values are lanthanum (La), atomic number $57,$ atomic weight $138.9055 ;$ cerium (Ce) atomic number $58,$ atomic weight $140.115 ;$ and praseodymium (Pr), atomic number $59,$ atomic weight $140.9076 .$ Using the data above, calculate the atomic weight, and identify the element if possible.

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
01:08

Problem 155

The mass spectrum of $\mathrm{CH}_{3} \mathrm{Cl}$ is illustrated here. You know that carbon has two stable isotopes, $^{12} \mathrm{C}$ and $^{13} \mathrm{C}$ with relative abundances of $98.9 \%$ and $1.1 \%,$ respectively, and chlorine has two isotopes, $^{35} \mathrm{Cl}$ and $^{37} \mathrm{Cl}$ with abundances of $75.77 \%$ and $24.23 \%,$ respectively.
(a) What molecular species gives rise to the lines at $m / Z$ of 50 and $52 ?$ Why is the line at 52 about
$1 / 3$ the height of the line at $50 ?$
(b) What species might be responsible for the line at $m / Z=51 ?$
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
03:04

Problem 156

The highest mass peaks in the mass spectrum of $\mathrm{Br}_{2}$ occur at $m / Z 158,160,$ and $162 .$ The ratio of intensities of these peaks is approximately $1: 2: 1 .$ Bromine has two stable isotopes, $^{79} \mathrm{Br}(50.7 \% \text { abundance })$ and $^{81} \mathrm{Br}$ $(49.3 \% \text { abundance })$
(a) What molecular species gives rise to each of these peaks?
(b) Explain the relative intensities of these peaks. (Hint:
Consider the probabilities of each atom combination.)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
07:53

Problem 157

If Epsom salt, $\mathrm{MgSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O},$ is heated to $250^{\circ} \mathrm{C},$ all
the water of hydration is lost. On heating a $1.687-\mathrm{g}$ sample of the hydrate, $0.824 \mathrm{g}$ of $\mathrm{MgSO}_{4}$ remains. How many molecules of water occur per formula unit of $\mathrm{MgSO}_{4} ?$

David Alvarez-Carbonell
David Alvarez-Carbonell
Numerade Educator
04:28

Problem 158

The "alum" used in cooking is potassium aluminum sulfate hydrate, $\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2} \cdot x \mathrm{H}_{2} \mathrm{O} .$ To find the value of $x,$ you can heat a sample of the compound to drive off all of the water and leave only $\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2}$. Assume you heat 4.74 g of the hydrated compound and that the sample loses $2.16 \mathrm{g}$ of water. What is the value of $x ?$

Joanna Josey
Joanna Josey
Numerade Educator
08:42

Problem 159

Tin metal (Sn) and purple iodine (I_) combine to form orange, solid tin iodide with an unknown formula.
$$
\text { Sn metal }+\text { solid } \mathrm{I}_{2} \rightarrow \text { solid } \mathrm{Sn}_{x} \mathrm{I}_{y}
$$
Weighed quantities of $\mathrm{Sn}$ and $\mathrm{I}_{2}$ are combined, where the quantity of $\mathrm{Sn}$ is more than is needed to react with all of the iodine. After $\mathrm{Sn}_{x} \mathrm{I}_{y}$ has been formed, it is isolated by filtration. The mass of excess tin is also determined. The following data were collected:
Mass of tin $(\mathrm{Sn})$ in the original mixture $1.056 \mathrm{g}$
Mass of iodine $\left(\mathrm{I}_{2}\right)$ in the original mixture $1.947 \mathrm{g}$ Mass of tin (Sn) recovered after reaction $\quad 0.601 \mathrm{g}$
What is the empirical formula of the tin iodide obtained?

Ayushi Sambyal
Ayushi Sambyal
Numerade Educator
05:57

Problem 160

When analyzed, an unknown compound gave these experimental results: $\mathrm{C}, 54.0 \% ; \mathrm{H}, 6.00 \% ;$ and $\mathrm{O}$ $40.0 \% .$ Four different students used these values to calculate the empirical formulas shown here. Which answer is correct? Why did some students not get the correct answer?
(a) $\mathrm{C}_{4} \mathrm{H}_{5} \mathrm{O}_{2}$
(b) $\mathrm{C}_{5} \mathrm{H}_{7} \mathrm{O}_{3}$
(c) $\mathrm{C}_{7} \mathrm{H}_{10} \mathrm{O}_{4}$
(d) $\mathrm{C}_{9} \mathrm{H}_{12} \mathrm{O}_{5}$

Muhammad Bin
Muhammad Bin
Numerade Educator
04:18

Problem 161

Two general chemistry students working together in the lab weigh out $0.832 \mathrm{g}$ of $\mathrm{CaCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ into a crucible. After heating the sample for a short time and allowing the crucible to cool, the students determine that the sample has a mass of 0.739 g. They then do a quick calculation. On the basis of this calculation, what should they do next?
(a) Congratulate themselves on a job well done.
(b) Assume the bottle of $\mathrm{CaCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ was mislabeled; it actually contained something different.
(c) Heat the crucible again, and then reweigh it.

Joanna Josey
Joanna Josey
Numerade Educator
01:37

Problem 162

To find the empirical formula of tin oxide, you first react tin metal with nitric acid in a porcelain crucible. The metal is converted to tin nitrate, but, on heating the nitrate strongly, brown nitrogen dioxide gas is evolved and tin oxide is formed. In the laboratory you collect the following data:
Mass of crucible $\quad 13.457 \mathrm{g}$ Mass of crucible plus tin $\quad 14.710 \mathrm{g}$ Mass of crucible after heating $15.048 \mathrm{g}$
What is the empirical formula of tin oxide?

Maryam Shahid
Maryam Shahid
Numerade Educator
00:25

Problem 163

Identify, from the list below, the information needed to calculate the number of atoms in $1.00 \mathrm{cm}^{3}$ of iron. Outline the procedure used in this calculation.
(a) the structure of solid iron
(b) the molar mass of iron
(c) Avogadro's number
(d) the density of iron
(e) the temperature
(f) iron's atomic number
(g) the number of iron isotopes

David Collins
David Collins
Numerade Educator
01:41

Problem 164

Consider the plot of relative element abundances on page $95 \mathrm{f}$. Is there a relationship between abundance and atomic number? Is there any difference between the relative abundance of an element of even atomic number and the relative abundance of an element of odd atomic number?

Maryam Shahid
Maryam Shahid
Numerade Educator
00:55

Problem 165

The photo here depicts what happens when a coil of magnesium ribbon and a few calcium chips are placed in water.
(a) Based on these observations, what might you expect to see when barium, another Group 2 A element, is placed in water?
(b) Give the period in which each element (Mg, Ca, and
Ba) is found; what correlation do you think you might find between the reactivity of these elements and their positions in the periodic table?
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator
00:38

Problem 166

A jar contains some number of jelly beans. To find out precisely how many are in the jar, you could dump them out and count them. How could you estimate their number without counting each one? (Chemists need to do just this kind of "bean counting" when they work with atoms and molecules. Atoms and molecules are too small to count one by one, so chemists have worked out other methods to determine the number of atoms in a sample.)
(FIGURE CAN'T COPY)

Carlene Jimenez
Carlene Jimenez
Numerade Educator