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Chapter 4

Molecules and Compounds

Educators

CK
+ 22 more educators

Problem 1

How do the properties of compounds compare to the properties of the elements from which they are composed?

CK
Chris K.
Numerade Educator

Problem 2

What is a chemical bond? Why do chemical bonds form?

CK
Chris K.
Numerade Educator

Problem 3

Explain the difference between an ionic bond and a covalent bond.

CK
Chris K.
Numerade Educator

Problem 4

List and describe the different ways to represent compounds. Why are there so many?

CK
Chris K.
Numerade Educator

Problem 5

What is the difference between an empirical formula and a molecular formula?

CK
Chris K.
Numerade Educator

Problem 6

How do you determine how many dots to put around the Lewis symbol of an element?

CK
Chris K.
Numerade Educator

Problem 7

Describe the octet rule in the Lewis model.

CK
Chris K.
Numerade Educator

Problem 8

According to the Lewis model, what is a chemical bond?

CK
Chris K.
Numerade Educator

Problem 9

How can you use Lewis structures to determine the formula of ionic compounds? Give an example.

CK
Chris K.
Numerade Educator

Problem 10

What is lattice energy?

Jessica L.
Florida International University

Problem 11

Why is the formation of solid sodium chloride from solid sodium and gaseous chlorine exothermic, even though it takes more energy to form the Na+ ion than the amount of energy released upon formation of Cl-?

Aadit S.
Numerade Educator

Problem 12

Explain how to write a formula for an ionic compound given the names of the metal and nonmetal (or polyatomic ion) in the compound.

Jessica L.
Florida International University

Problem 13

Explain how to name binary ionic compounds. How do you name an ionic compound if it contains a polyatomic ion?

Aadit S.
Numerade Educator

Problem 14

Why do the names of some ionic compounds include the charge of the metal ion while others do not?

Jessica L.
Florida International University

Problem 15

Within a covalent Lewis structure, what is the difference between lone pair and bonding pair electrons?

Aadit S.
Numerade Educator

Problem 16

In what ways are double and triple covalent bonds different from single covalent bonds?

Jessica L.
Florida International University

Problem 17

How does the Lewis model for covalent bonding account for why certain combinations of atoms are stable while others are not?

Aadit S.
Numerade Educator

Problem 18

How does the Lewis model for covalent bonding account for the relatively low melting and boiling points of molecular compounds (compared to ionic compounds)?

Jessica L.
Florida International University

Problem 19

Explain how to name molecular inorganic compounds.

Aadit S.
Numerade Educator

Problem 20

How many atoms are specified by each of these prefixes: mono, di, tri, tetra, penta, hexa?

Jessica L.
Florida International University

Problem 21

What is the formula mass for a compound? Why is it useful?

Aadit S.
Numerade Educator

Problem 22

Explain how the information in a chemical formula can be used to determine how much of a particular element is present in a given amount of a compound. Provide some examples of how this might be useful.

Jessica L.
Florida International University

Problem 23

What is mass percent composition? Why is it useful?

Aadit S.
Numerade Educator

Problem 24

Which kinds of conversion factors are inherent in chemical formulas? Provide an example.

Jessica L.
Florida International University

Problem 25

Which kind of chemical formula can be obtained from experimental data showing the relative masses of the elements in a compound?

Aadit S.
Numerade Educator

Problem 26

How can a molecular formula be obtained from an empirical formula? What additional information is required?

Jessica L.
Florida International University

Problem 27

What is combustion analysis? What is it used for?

Aadit S.
Numerade Educator

Problem 28

Which elements are normally present in organic compounds?

Jessica L.
Florida International University

Problem 29

Classify each compound as ionic or molecular.
a. CO2
b. NiCl2
c. NaI
d. PCl3

Aadit S.
Numerade Educator

Problem 30

Classify each compound as ionic or molecular.
a. CF2Cl2
b. CCl4
c. PtO2
d. SO3

David C.
Numerade Educator

Problem 31

Determine the empirical formula for the compound represented by each molecular formula.
a. N2O4
b. C5H12
c. C4H10

Thomas W.
Numerade Educator

Problem 32

Determine the empirical formula for the compound represented by each molecular formula.
a. C2H4
b. C6H12O6
c. NH3

Jessica L.
Florida International University

Problem 33

Determine the number of each type of atom in each formula.
a. Mg3(PO4)2
b. BaCl2
c. Fe(NO2)2
d. Ca(OH)2

Charotte M.
Numerade Educator

Problem 34

Determine the number of each type of atom in each formula.
a. Ca(NO2)2
b. CuSO4
c. Al(NO3)3
d. Mg(HCO3)

Jessica L.
Florida International University

Problem 35

Write a chemical formula for each molecular model. (See Appendix II A for color codes.)

Aadit S.
Numerade Educator

Problem 36

Write a chemical formula for each molecular model. (See Appendix II A for color codes.)

Jessica L.
Florida International University

Problem 37

Write an electron configuration for N. Then write a Lewis symbol for N and show which electrons from the electron configuration are included in the Lewis symbol.

Aadit S.
Numerade Educator

Problem 38

Write an electron configuration for Ne. Then write a Lewis symbol for Ne and show which electrons from the electron configuration are included in the Lewis symbol.

Jessica L.
Florida International University

Problem 39

Write a Lewis symbol for each atom or ion.
a. Al
b. Na+
c. Cl
d. Cl-

Aadit S.
Numerade Educator

Problem 40

Write a Lewis symbol for each atom or ion.
a. S2-
b. Mg
c. Mg2+
d. P

Jessica L.
Florida International University

Problem 41

Write the Lewis symbols that represent the ions in each ionic compound.
a. NaF
b. CaO
c. SrBr2
d. K2O

Aadit S.
Numerade Educator

Problem 42

Write the Lewis symbols that represent the ions in each ionic compound.
a. SrO
b. Li2S
c. CaI2
d. RbF

Jessica L.
Florida International University

Problem 43

Use Lewis symbols to determine the formula for the compound that forms between each pair of elements.
a. Sr and Se
b. Ba and Cl
c. Na and S
d. Al and O

Aadit S.
Numerade Educator

Problem 44

Use Lewis symbols to determine the formula for the compound that forms between each pair of elements.
a. Ca and N
b. Mg and I
c. Ca and S
d. Cs and F

Jessica L.
Florida International University

Problem 45

The lattice energy of CsF is -744 kJ>mol, whereas that of BaO is -3029 kJ>mol. Explain this large difference in lattice energy.

Aadit S.
Numerade Educator

Problem 46

Rubidium iodide has a lattice energy of -617 kJ>mol, while potassium bromide has a lattice energy of -671 kJ>mol. Why is the lattice energy of potassium bromide more exothermic than the lattice energy of rubidium iodide?

Jessica L.
Florida International University

Problem 47

Write a formula for the ionic compound that forms between each pair of elements.
a. calcium and oxygen
b. zinc and sulfur
c. rubidium and bromine
d. aluminum and oxygen

Aadit S.
Numerade Educator

Problem 48

Write a formula for the ionic compound that forms between each pair of elements.
a. silver and chlorine
b. sodium and sulfur
c. aluminum and sulfur
d. potassium and chlorine

Jessica L.
Florida International University

Problem 49

Write a formula for the compound that forms between calcium and each polyatomic ion.
a. hydroxide
b. chromate
c. phosphate
d. cyanide

Aadit S.
Numerade Educator

Problem 50

Write a formula for the compound that forms between potassium and each polyatomic ion.
a. carbonate
b. phosphate
c. hydrogen phosphate
d. acetate

Jessica L.
Florida International University

Problem 51

Name each ionic compound.
a. Mg3N2
b. KF
c. Na2O
d. Li2S
e. CsF
f. KI

Aadit S.
Numerade Educator

Problem 52

Name each ionic compound.
a. SnCl4
b. PbI2
c. Fe2O3
d. CuI2
e. HgBr2
f. CrCl2

Jessica L.
Florida International University

Problem 53

Name each ionic compound.
a. SnO
b. Cr2S3
c. RbI
d. BaBr2

Aadit S.
Numerade Educator

Problem 54

Name each ionic compound.
a. BaS
b. FeCl3
c. PbI4
d. SrBr2

Jessica L.
Florida International University

Problem 55

Name each ionic compound containing a polyatomic ion.
a. CuNO2
b. Mg(C2H3O2)2
c. Ba(NO3)2
d. Pb(C2H3O2)2

Aadit S.
Numerade Educator

Problem 56

Name each ionic compound containing a polyatomic ion.
a. Ba(OH)2
b. NH4I
c. NaBrO4
d. Fe(OH)3

Jessica L.
Florida International University

Problem 57

Write the formula for each ionic compound.
a. sodium hydrogen sulfite
b. lithium permanganate
c. silver nitrate
d. potassium sulfate
e. rubidium hydrogen sulfate
f. potassium hydrogen carbonate

Aadit S.
Numerade Educator

Problem 58

Write the formula for each ionic compound.
a. copper(II) chloride
b. copper(I) iodate
c. lead(II) chromate
d. calcium fluoride
e. potassium hydroxide
f. iron(II) phosphate

Jessica L.
Florida International University

Problem 59

Write the name from the formula or the formula from the name for each hydrated ionic compound.
a. CoSO4 # 7H2O
b. iridium(III) bromide tetrahydrate
c. Mg(BrO3)2 # 6H2O
d. potassium carbonate dihydrate

Aadit S.
Numerade Educator

Problem 60

Write the name from the formula or the formula from the name for each hydrated ionic compound.
a. cobalt(II) phosphate octahydrate
b. BeCl2 # 2H2O
c. chromium(III) phosphate trihydrate
d. LiNO2 # H2O

Jessica L.
Florida International University

Problem 61

Use covalent Lewis structures to explain why each element (or family of elements) occurs as diatomic molecules.
a. hydrogen
b. the halogens
c. oxygen
d. nitrogen

Aadit S.
Numerade Educator

Problem 62

Use covalent Lewis structures to explain why the compound that forms between nitrogen and hydrogen has the formula NH3. Show why NH2 and NH4 are not stable.

Jessica L.
Florida International University

Problem 63

Name each molecular compound.
a. CO
b. NI3
c. SiCl4
d. N4Se4

David C.
Numerade Educator

Problem 64

Name each molecular compound.
a. SO3
b. SO2
c. BrF5
d. NO

Jessica L.
Florida International University

Problem 65

Write a formula for each molecular compound.
a. phosphorus trichloride
b. chlorine monoxide
c. disulfur tetrafluoride
d. phosphorus pentafluoride

Aadit S.
Numerade Educator

Problem 66

Write a formula for each molecular compound.
a. boron tribromide
b. dichlorine monoxide
c. xenon tetrafluoride
d. carbon tetrabromide

Jessica L.
Florida International University

Problem 67

Name each compound. (Refer to the nomenclature flowchart found in the Key Concepts section of the Chapter in Review.)
a. SrCl2
b. SnO2
c. P2S5

Aadit S.
Numerade Educator

Problem 68

Name each compound. (Refer to the nomenclature flowchart found in the Key Concepts section of the Chapter in Review.)
a. B2Cl2
b. BaCl2
c. CrCl3

Jessica L.
Florida International University

Problem 69

Name each compound. (Refer to the nomenclature flowchart found in the Key Concepts section of the Chapter in Review.)
a. KClO3
b. I2O5
c. PbSO4

Aadit S.
Numerade Educator

Problem 70

Name each compound. (Refer to the nomenclature flowchart found in the Key Concepts section of the Chapter in Review.)
a. XeO3
b. KClO
c. CoSO4

Jessica L.
Florida International University

Problem 71

Calculate the formula mass for each compound.
a. NO2
b. C4H10
c. C6H12O6
d. Cr(NO3)3

Aadit S.
Numerade Educator

Problem 72

Calculate the formula mass for each compound.
a. MgBr2
b. HNO2
c. CBr4
d. Ca(NO3)2

Jessica L.
Florida International University

Problem 73

Calculate the number of moles in each sample.
a. 72.5 g CCl4
b. 12.4 g C12H22O11
c. 25.2 kg C2H2
d. 12.3 g of dinitrogen monoxide

Charotte M.
Numerade Educator

Problem 74

Calculate the mass of each sample.
a. 15.7 mol HNO3
b. 1.04 * 10-3 mol H2O2
c. 72.1 mmol SO2
d. 1.23 mol xenon difluoride

Jessica L.
Florida International University

Problem 75

Determine the number of moles (of molecules or formula units) in each sample.
a. 25.5 g NO2
b. 1.25 kg CO2
c. 38.2 g KNO3
d. 155.2 kg Na2SO4

Aadit S.
Numerade Educator

Problem 76

Determine the number of moles (of molecules or formula units) in each sample.
a. 55.98 g CF2Cl2
b. 23.6 kg Fe(NO3)2
c. 0.1187 g C8H18
d. 195 kg CaO

David C.
Numerade Educator

Problem 77

How many molecules are in each sample?
a. 6.5 g H2O
b. 389 g CBr4
c. 22.1 g O2
d. 19.3 g C8H10

Charotte M.
Numerade Educator

Problem 78

How many molecules (or formula units) are in each sample?
a. 85.26 g CCl4
b. 55.93 kg NaHCO3
c. 119.78 g C4H10
d. 4.59 * 105 g Na3PO4

David C.
Numerade Educator

Problem 79

Calculate the mass (in g) of each sample.
a. 5.94 * 1020 SO3 molecules
b. 2.8 * 1022 H2O molecules
c. 1 glucose molecule (C6H12O6)

Aadit S.
Numerade Educator

Problem 80

Calculate the mass (in g) of each sample.
a. 4.5 * 1025 O3 molecules
b. 9.85 * 1019 CCl2F2 molecules
c. 1 water molecule

Aadit S.
Numerade Educator

Problem 81

A sugar crystal contains approximately 1.8 * 1017 sucrose (C12H22O11) molecules. What is its mass in mg?

UO
Umut O.
Texas Tech University

Problem 82

A salt crystal has a mass of 0.12 mg. How many NaCl formula units does it contain?

Jessica L.
Florida International University

Problem 83

Calculate the mass percent composition of carbon in each carbon-containing compound.
a. CH4
b. C2H6
c. C2H2
d. C2H5Cl

Aadit S.
Numerade Educator

Problem 84

Calculate the mass percent composition of nitrogen in each nitrogen-containing compound.
a. N2O
b. NO
c. NO2
d. HNO3

DC
Damilola C.
Numerade Educator

Problem 85

Most fertilizers consist of nitrogen-containing compounds such as NH3, CO(NH2)2, NH4NO3, and (NH4)2SO4. Plants use the nitrogen content in these compounds for protein synthesis. Calculate the mass percent composition of nitrogen in each of the fertilizers named in this problem. Which fertilizer has the highest nitrogen content?

Aadit S.
Numerade Educator

Problem 86

Iron in the earth is in the form of iron ore. Common ores include Fe2O3 (hematite), Fe3O4 (magnetite), and FeCO3 (siderite). Calculate the mass percent composition of iron for each of these iron ores. Which ore has the highest iron content?

Jessica L.
Florida International University

Problem 87

Copper(II) fluoride contains 37.42% F by mass. Calculate the mass of fluorine (in g) contained in 55.5 g of copper(II) fluoride.
20.8 $\mathrm{gF}$

Keenan M.
University of Miami

Problem 88

Silver chloride, often used in silver plating, contains 75.27% Ag by mass. Calculate the mass of silver chloride required to plate 155 mg of pure silver.

David C.
Numerade Educator

Problem 89

The iodide ion is a dietary mineral essential to good nutrition. In countries where potassium iodide is added to salt, iodine deficiency (goiter) has been almost completely eliminated. The recommended daily allowance (RDA) for iodine is 150 mg>day. How much potassium iodide (76.45% I) must you consume to
meet the RDA?

Aadit S.
Numerade Educator

Problem 90

The American Dental Association recommends that an adult female should consume 3.0 mg of fluoride (F-) per day to prevent tooth decay. If the fluoride is consumed in the form of sodium fluoride (45.24% F), what amount of sodium fluoride contains the recommended amount of fluoride?

Aadit S.
Numerade Educator

Problem 91

Write a ratio showing the relationship between the molar amounts of each element for each compound.

Aadit S.
Numerade Educator

Problem 92

Write a ratio showing the relationship between the molar amounts of each element for each compound.

Aadit S.
Numerade Educator

Problem 93

Determine the number of moles of hydrogen atoms in each sample.
a. 0.0885 mol C4H10
b. 1.3 mol CH4
c. 2.4 mol C6H12
d. 1.87 mol C8H18

Aadit S.
Numerade Educator

Problem 94

Determine the number of moles of oxygen atoms in each sample.
a. 4.88 mol H2O2
b. 2.15 mol N2O
c. 0.0237 mol H2CO3
d. 24.1 mol CO2

David C.
Numerade Educator

Problem 95

Calculate mass (in grams) of sodium in 8.5 g of each sodium-containing food additive.
a. NaCl (table salt)
b. Na3PO4 (sodium phosphate)
c. NaC7H5O2 (sodium benzoate)
d. Na2C6H6O7 (sodium hydrogen citrate)

Aadit S.
Numerade Educator

Problem 96

Calculate the mass (in kilograms) of chlorine in 25 kg of each chlorofluorocarbon (CFC).
a. CF2Cl2
b. CFCl3
c. C2F3Cl3
d. CF3Cl

David C.
Numerade Educator

Problem 97

A chemist decomposes samples of several compounds; the masses of their constituent elements are shown. Calculate the empirical formula for each compound.
a. 1.651 g Ag, 0.1224 g O
b. 0.672 g Co, 0.569 g As, 0.486 g O
c. 1.443 g Se, 5.841 g Br

Charotte M.
Numerade Educator

Problem 98

A chemist decomposes samples of several compounds; the masses of their constituent elements are shown. Calculate the empirical formula for each compound.
a. 1.245 g Ni, 5.381 g I
b. 2.677 g Ba, 3.115 g Br
c. 2.128 g Be, 7.557 g S, 15.107 g O

Aadit S.
Numerade Educator

Problem 99

Calculate the empirical formula for each stimulant based on its elemental mass percent composition.
a. nicotine (found in tobacco leaves): C 74.03%, H 8.70%, N 17.27%
b. caffeine (found in coffee beans): C 49.48%, H 5.19%, N 28.85%, O 16.48%

Aadit S.
Numerade Educator

Problem 100

Calculate the empirical formula for each natural flavor based on its elemental mass percent composition.
a. methyl butyrate (component of apple taste and smell): C 58.80%, H 9.87%, O 31.33%
b. vanillin (responsible for the taste and smell of vanilla): C 63.15%, H 5.30%, O 31.55%

Aadit S.
Numerade Educator

Problem 101

The elemental mass percent composition of ibuprofen is 75.69% C, 8.80% H, and 15.51% O. Determine the empirical formula of ibuprofen.

Aadit S.
Numerade Educator

Problem 102

The elemental mass percent composition of ascorbic acid (vitamin C) is 40.92% C, 4.58% H, and 54.50% O. Determine the empirical formula of ascorbic acid.

Aadit S.
Numerade Educator

Problem 103

A 0.77-mg sample of nitrogen reacts with chlorine to form 6.61 mg of the chloride. Determine the empirical formula of nitrogen chloride.

Aadit S.
Numerade Educator

Problem 104

A 45.2-mg sample of phosphorus reacts with selenium to form 131.6 mg of the selenide. Determine the empirical formula of phosphorus selenide.

Aadit S.
Numerade Educator

Problem 105

The empirical formula and molar mass of several compounds are listed. Find the molecular formula of each compound.
a. C6H7N, 186.24 g>mol
b. C2HCl, 181.44 g>mol
c. C5H10NS2, 296.54 g>mol

Charotte M.
Numerade Educator

Problem 106

The molar mass and empirical formula of several compounds are listed. Find the molecular formula of each compound.
a. C4H9, 114.22 g>mol
b. CCl, 284.77 g>mol
c. C3H2N, 312.29 g>mol

Charotte M.
Numerade Educator

Problem 107

Combustion analysis of a hydrocarbon produced 33.01 g CO2 and 13.51 g H2O. Calculate the empirical formula of the hydrocarbon.

Aadit S.
Numerade Educator

Problem 108

Combustion analysis of naphthalene, a hydrocarbon used in mothballs, produced 8.80 g CO2 and 1.44 g H2O. Calculate the empirical formula for naphthalene.

Aadit S.
Numerade Educator

Problem 109

The foul odor of rancid butter is due largely to butyric acid, a compound containing carbon, hydrogen, and oxygen. Combustion analysis of a 4.30-g sample of butyric acid produces 8.59 g CO2 and 3.52 g H2O. Determine the empirical formula for butyric acid.

Aadit S.
Numerade Educator

Problem 110

Tartaric acid is the white, powdery substance that coats tart candies such as Sour Patch Kids. Combustion analysis of a 12.01-g sample of tartaric acid-which contains only carbon, hydrogen, and oxygen-produces 14.08 g CO2 and 4.32 g H2O. Determine the empirical formula for tartaric acid.

Aadit S.
Numerade Educator

Problem 111

Classify each compound as organic or inorganic.
a. CaCO3
b. C4H8
c. C4H6O6
d. LiF

JV
Jacob V.
Numerade Educator

Problem 112

Classify each compound as organic or inorganic.
a. C8H18
b. CH3NH2
c. CaO
d. FeCO3

Charotte M.
Numerade Educator

Problem 113

Determine whether each compound is a hydrocarbon.

Thomas W.
Numerade Educator

Problem 114

Determine whether each compound is a hydrocarbon.

Jessica L.
Florida International University

Problem 115

How many molecules of ethanol (C2H5OH) (the alcohol in alcoholic beverages) are present in 145 mL of ethanol? The density of ethanol is 0.789 g>cm3.

Aadit S.
Numerade Educator

Problem 116

A drop of water has a volume of approximately 0.05 mL. How many water molecules does it contain? The density of water is 1.0 g>cm3.

Aadit S.
Numerade Educator

Problem 117

Determine the chemical formula of each compound and use it to calculate the mass percent composition of each constituent element.
a. potassium chromate
b. lead(II) phosphate
c. cobalt(II) bromide

Aadit S.
Numerade Educator

Problem 118

Determine the chemical formula of each compound and use it to calculate the mass percent composition of each constituent element.
a. phosphorus pentachloride
b. nitrogen triiodide
c. carbon dioxide

Aadit S.
Numerade Educator

Problem 119

A Freon leak in the air conditioning system of an old car releases 25 g of CF2Cl2 per month. What mass of chlorine does this car emit into the atmosphere each year?

Aadit S.
Numerade Educator

Problem 120

A Freon leak in the air conditioning system of a large building releases 12 kg of CHF2Cl per month. If the leak is allowed to continue, how many kilograms of Cl are emitted into the atmosphere each year?

Aadit S.
Numerade Educator

Problem 121

A metal (M) forms a compound with the formula MCl3. If the compound contains 65.57% Cl by mass, what is the identity of the metal?

Aadit S.
Numerade Educator

Problem 122

A metal (M) forms an oxide with the formula M2O. If the oxide contains 16.99% O by mass, what is the identity of the metal?

Aadit S.
Numerade Educator

Problem 123

Estradiol is a female sexual hormone that causes maturation and maintenance of the female reproductive system. Elemental analysis of estradiol gives the following mass percent composition: C $79.37 \%,$ H $8.88 \%,$ O $11.75 \% .$ The molar mass of estradiol is $272.37 \mathrm{~g} / \mathrm{mol} .$ Find the molecular formula of estradiol.

Aadit S.
Numerade Educator

Problem 124

Fructose is a common sugar found in fruit. Elemental analysis of fructose gives the following mass percent composition: C 40.00%, H 6.72%, O 53.28%. The molar mass of fructose is 180.16 g>mol. Find the molecular formula of fructose.

Aadit S.
Numerade Educator

Problem 125

Combustion analysis of a 13.42-g sample of equilin (which contains only carbon, hydrogen, and oxygen) produces 39.61 g CO2 and 9.01 g H2O. The molar mass of equilin is 268.34 g>mol. Find its molecular formula.

Aadit S.
Numerade Educator

Problem 126

Estrone, which contains only carbon, hydrogen, and oxygen, is a female sexual hormone that occurs in the urine of pregnant women. Combustion analysis of a 1.893-g sample of estrone produces 5.545 g of CO2 and 1.388 g H2O. The molar mass of estrone is 270.36 g>mol. Find its molecular formula.

Aadit S.
Numerade Educator

Problem 127

Epsom salts is a hydrated ionic compound with the following formula: MgSO4 # x H2O. A 4.93-g sample of Epsom salts was heated to drive off the water of hydration. The mass of the sample after complete dehydration was 2.41 g. Find the number of waters of hydration (x) in Epsom salts

Aadit S.
Numerade Educator

Problem 128

A hydrate of copper(II) chloride has the following formula: CuCl2 # x H2O. The water in a 3.41-g sample of the hydrate is driven off by heating. The remaining sample has a mass of 2.69 g. Find the number of waters of hydration (x) in the hydrate.

Aadit S.
Numerade Educator

Problem 129

A compound of molar mass 177 g>mol contains only carbon, hydrogen, bromine, and oxygen. Analysis reveals that the compound contains 8 times as much carbon as hydrogen by mass. Find the molecular formula.

Charotte M.
Numerade Educator

Problem 130

Researchers obtain the following data from experiments to find the molecular formula of benzocaine, a local anesthetic, which contains only carbon, hydrogen, nitrogen, and oxygen. Complete combustion of a 3.54-g sample of benzocaine with excess O2 forms 8.49 g of CO2 and 2.14 g H2O. Another sample of mass 2.35 g is found to contain 0.199 g of N. The molar mass of benzocaine is found to be 165 g>mol. Find the molecular formula of benzocaine.

Aadit S.
Numerade Educator

Problem 131

Find the total number of atoms in a sample of cocaine hydrochloride, C17H22CINO4, of mass 23.5 mg.

Aadit S.
Numerade Educator

Problem 132

Vanadium forms four different oxides in which the percent by mass of vanadium is, respectively, (a) 76%, (b) 68%, (c) 61%, and (d) 56%. Determine the formula and the name of each one of these oxides.

Aadit S.
Numerade Educator

Problem 133

The chloride of an unknown metal is believed to have the formula MCl3. A 2.395-g sample of the compound contains 3.606 * 10-2 mol Cl. Find the atomic mass of M.

Charotte M.
Numerade Educator

Problem 134

Write the structural formulas of two different compounds that each has the molecular formula C4H10.

Jessica L.
Florida International University

Problem 135

A chromium-containing compound has the formula FexCryO4 and is 28.59% oxygen by mass. Find x and y.

Charotte M.
Numerade Educator

Problem 136

A phosphorus compound that contains 34.00% phosphorus by mass has the formula X3P2. Identify the element X.

Aadit S.
Numerade Educator

Problem 137

A particular brand of beef jerky contains 0.0552% sodium nitrite by mass and is sold in an 8.00-oz bag. What mass of sodium does the sodium nitrite contribute to the sodium content of the bag of beef jerky?

Aadit S.
Numerade Educator

Problem 138

Phosphorus is obtained primarily from ores containing calcium phosphate. If a particular ore contains 57.8% calcium phosphate, what minimum mass of the ore must be processed to obtain 1.00 kg of phosphorus?

Aadit S.
Numerade Educator

Problem 139

A mixture of NaCl and NaBr has a mass of 2.00 g and contains 0.75 g of Na. What is the mass of NaBr in the mixture?

Aadit S.
Numerade Educator

Problem 140

Three pure compounds form when 1.00-g samples of element X combine with, respectively, 0.472 g, 0.630 g, and 0.789 g of element Z. The first compound has the formula X2Z3. Find the empirical formulas of the other two compounds.

Aadit S.
Numerade Educator

Problem 141

A mixture of CaCO3 and (NH4)2CO3 is 61.9% CO3 by mass. Find the mass percent of CaCO3 in the mixture.

Charotte M.
Numerade Educator

Problem 142

A mixture of 50.0 g of S and 1.00 * 102 g of Cl2 reacts completely to form S2Cl2 and SCl2. What mass of S2Cl2 forms?

Aadit S.
Numerade Educator

Problem 143

Because of increasing evidence of damage to the ozone layer, chlorofluorocarbon (CFC) production was banned in 1996. However, there are about 100 million auto air conditioners in operation that still use CFC-12 (CF2Cl2). These air conditioners are recharged from stockpiled supplies of CFC-12. If each of the 100 million automobiles contains 1.1 kg of CFC-12 and leaks 25% of its CFC-12 into the atmosphere per year, how much chlorine, in kg, is added to the atmosphere each year due to auto air conditioners? (Assume two significant figures in your calculations.)

Aadit S.
Numerade Educator

Problem 144

A particular coal contains 2.55% sulfur by mass. When the coal is burned, it produces SO2 emissions, which combine with rainwater to produce sulfuric acid. Use the formula of sulfuric acid to calculate the mass percent of S in sulfuric acid. Then determine how much sulfuric acid (in metric tons) is produced by the combustion of 1.0 metric ton of this coal. (A metric ton is 1000 kg.)

Charotte M.
Numerade Educator

Problem 145

Lead is found in Earth's crust as several different lead ores. Suppose a certain rock is 38.0% PbS (galena), 25.0% PbCO3 (cerussite), and 17.4% PbSO4 (anglesite). The remainder of the rock is composed of substances containing no lead. How much of this rock (in kg) must be processed to obtain 5.0 metric tons of lead? (A metric ton is 1000 kg.)

David C.
Numerade Educator

Problem 146

A 2.52-g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen, and sulfur is burned in excess oxygen to yield 4.23 g of CO2 and 1.01 g of H2O. Another sample of the same compound, of mass 4.14 g, yields 2.11 g of SO3. A third sample, of mass 5.66 g, yields 2.27 g of HNO3. Calculate the
empirical formula of the compound. (Hint: Use the first set of data to determine % C and % H by mass. Use the second and third sets of data to determine % S and % N by mass. Then determine % O by mass by difference from 100%.)

David C.
Numerade Educator

Problem 147

A compound of molar mass 229 contains only carbon, hydrogen, iodine, and sulfur. Analysis shows that a sample of the compound contains 6 times as much carbon as hydrogen, by mass. Calculate the molecular formula of the compound.

Aadit S.
Numerade Educator

Problem 148

The elements X and Y form a compound that is 40% X and 60% Y by mass. The atomic mass of X is twice that of Y. What is the empirical formula of the compound?

Aadit S.
Numerade Educator

Problem 149

A compound of X and Y is 13 X by mass. The atomic mass of element X is one-third the atomic mass of element Y. Find the empirical formula of the compound.

Aadit S.
Numerade Educator

Problem 150

A mixture of carbon and sulfur has a mass of 9.0 g. Complete combustion with excess O2 gives 23.3 g of a mixture of CO2 and SO2. Find the mass of sulfur in the original mixture.

Aadit S.
Numerade Educator

Problem 151

When molecules are represented by molecular models, what does each sphere represent? How big is the nucleus of an atom in comparison to the sphere used to represent an atom in a molecular model?

Aadit S.
Numerade Educator

Problem 152

Without doing any calculations, determine which element in each of the compounds will have the highest mass percent composition.
a. CO
b. N2O
c. C6H12O6
d. NH3

Jessica L.
Florida International University

Problem 153

Explain the problem with this statement and correct it: "The chemical formula for ammonia (NH3) indicates that ammonia contains 3 grams of hydrogen to each gram of nitrogen."

Aadit S.
Numerade Educator

Problem 154

Without doing any calculations, arrange the elements in H2SO4 in order of decreasing mass percent composition.

Jessica L.
Florida International University

Problem 155

Using group members to play the roles of nuclei and electrons, demonstrate the formation of an ionic bond between Na and Cl. Demonstrate the formation of the covalent bonds in H2O.

Thomas W.
Numerade Educator

Problem 156

Create a flowchart with a series of simple questions that can be used to determine whether a chemical formula is that of an atomic element, a molecular element, a molecular compound, or an ionic compound. Use your flowchart to identify the correct category for P4, KCl, CH4, Ne, and NH4NO3.

Aadit S.
Numerade Educator

Problem 157

Have each member of your group list one similarity or difference between the naming conventions for ionic and the naming conventions of molecular compounds.

Thomas W.
Numerade Educator

Problem 158

A compound isolated from the rind of lemons is 88.14% carbon and 11.86% hydrogen by mass. How many grams of C and H are there in a 100.0-g sample of this substance? How many moles of C and H? What is the empirical formula? The molar mass is determined to be 136.26 g>mol. What is the molecular formula? Which step of the process just described does your group understand the least? Which step will be most challenging for the members of your group to remember?

Thomas W.
Numerade Educator

Problem 159

The amount of carbon dioxide in the atmosphere has been increasing over the past century as a result of the combustion of fossil fuels (coal, oil, and natural gas). Carbon dioxide is a greenhouse gas that plays a significant role in climate. The increase in carbon dioxide is correlated with changes in climate that have climate scientists concerned. The graph shown here illustrates the increase in atmospheric carbon dioxide from 1860 to the present. Study the graph and answer the questions that follow.

Atmospheric carbon dioxide concentration from 1850 to present.

a. By how much did the level of carbon dioxide (in ppmv) increase between 1880 and the present day?
b. What is the percent increase in the level of carbon dioxide between 1880 and the present day?
c. Assuming that the total volume of air in the atmosphere around Earth is 5.1 * 109 km3 and that the concentration of CO2 is uniform throught this volume, what is the present-day volume of CO2 in the atmosphere?
d. Determine the percentage average yearly increase in atmospheric CO2 from 1960 to the present day.
e. If atmospheric carbon dioxide continues to increase at the rate you determined in part d, what will its concentration (in ppmv) be in the year 2040?

Thomas W.
Numerade Educator