Chemistry

Kenneth W Whitten

Chapter 2

Chemical Formulas and Composition Stoichiometry - all with Video Answers

Educators

+ 2 more educators

Chapter Questions

Problem 1

(a) De“ne •stoichiometry.Ž (b) Distinguish between composition stoichiometry and reaction stoichiometry.

Lottie Adams

Lottie Adams

Numerade Educator

Problem 2

Give two examples of molecules that represent allotropes. Which of the compounds you selected are diatomic?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 3

For each of the following elements, give the number of protons in the nucleus, the charge of the nucleus, and the number of electrons surrounding the nucleus: (a) helium; (b) chlorine; (c) calcium; (d) zinc; (e) boron.

Crystal Wang

Numerade Educator

Problem 4

Draw the structural formulas and the ball-and-stick models of water and ethanol (CH3CH 2OH). What arrangement of atoms is alike in these two compounds?

Lottie Adams

Numerade Educator

Problem 5

Draw the space-“lling and ball-and-stick models of ethanol (CH3CH 2OH) and methanol (CH3OH). What structural features do they have in common?

Lottie Adams

Numerade Educator

Problem 6

What structural feature distinguishes organic compounds from inorganic compounds? Draw a molecular model of an organic compound and an inorganic compound.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 7

Give the names and formulas of the compounds in Table 2-1 that are organic compounds.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 8

Select a compound from Table 2-1 that contains only carbon and hydrogen and is not one of the compounds in Figure 1-5. Draw a ball-and-stick model of the selected compound.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 9

Select a compound from Table 2-1 that contains carbon, hydrogen and oxygen and is not one of the compounds in Figure 1-5. Draw a ball-and-stick model of the selected compound.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 10

Give examples of molecules that contain (a) three atoms of oxygen; (b) only two atoms of hydrogen; (c) four atoms total; (d) eight atoms total; (e) eight atoms of hydrogen.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 11

De“ne the following terms: (a) formula weight (or formula mass); (b) molecular weight (or molecular mass); (c) structural formula; (d) ion. Names and Formulas

Lottie Adams

Numerade Educator

Problem 12

Name the following compounds: (a) HNO3; (b) C5H 12; (c) NH 3; (d) CH3OH.

Lottie Adams

Numerade Educator

Problem 13

Write formulas for the following compounds: (a) butane; (b) ethyl alcohol; (c) sulfur trioxide; (d) acetone; (e) carbon tetrachloride.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 14

Write the chemical symbol for each of the following ions. Classify each as a monatomic or polyatomic ion. Classify each as a cation or an anion. (a) magnesium ion; (b) sul“te ion; (c) copper(I) ion; (d) ammonium ion; (e) oxide ion.

Lottie Adams

Numerade Educator

Problem 15

Name each of the following compounds: (a) MgCl 2; (b) Fe(NO3)2; (c) Na2SO4; (d) Ca(OH)2; (e) FeSO4.

Lottie Adams

Numerade Educator

Problem 16

Write the chemical formula and name for each of the ionic compounds that could be formed by the combination of two of the following ions: Ca2 ; Na ; Br ; and CH 3COO .

Crystal Wang

Numerade Educator

Problem 17

Write the chemical formula for the ionic compound formed between each of the following pairs of ions. Name each compound. (a) Naand OH ; (b) Al3 and CO3 2 ; (c) Na and PO4 3 ; (d) Mg2 and NO2 ; (e) Fe2 and CO3 2.

Lottie Adams

Numerade Educator

Problem 18

Write the chemical formula for the ionic compound formed between each of the following pairs of ions. Name each compound. (a) Cu2 and CO3 2 ; (b) Sr2 and Br ; (c) NH 4 and CO3 2 ; (d) Zn2 and O2 ; (e) Fe3 and SO4 2 .

Lottie Adams

Numerade Educator

Problem 19

A student was asked to write the chemical formulas for the following compounds. If the formulas are correct, say so. Explain why any that are incorrect are in error, and correct them. (a) potassium iodide, PI; (b) copper(I) nitrate, CuNO 3; (c) silver carbonate, AgCO4.

Lottie Adams

Numerade Educator

Problem 20

Convert each of the following into a correct formula represented with correct notation: (a) NaCO3; (b) Mg2Cl; (c) Zn(OH) 3; (d) (NH 4)3S; (e) Na2(I)2.

Lottie Adams

Numerade Educator

Problem 21

Convert each of the following into a correct formula represented with correct notation. (a) AlO3H 3; (b) Mg3CO3; (c) Zn(CO3)2; (d) (NH 4)3SO4; (e) Zn2(SO4)2.

Lottie Adams

Numerade Educator

Problem 22

Write the formula of the compound produced by the combination of each of the following pairs of elements. Name each compound. (a) sodium and chlorine; (b) magnesium and bromine; (c) sulfur and oxygen; (d) calcium and oxygen; (e) potassium and sulfur; (f ) aluminum and oxygen; (e) potassium and sulfur; (f ) aluminum and bromine.

Lottie Adams

Numerade Educator

Problem 23

Write the chemical formula of each of the following: (a) calcium carbonate„major component of coral, seashells, and limestone„found in antacid preparations; (b) magnesium hydroxide„found in milk of magnesia; (c) acetic acid„the acid in vinegar; (d) sodium hydroxide„common name is lye; (e) zinc oxide„used to protect from sunlight•s UV rays when blended in an ointment. Zinc oxide used as a sunscreen Atomic and Formula Weights.

Lottie Adams

Numerade Educator

Problem 24

What is the mass ratio (four signi“cant “gures) of one atom of Rb to one atom of Br?

Lottie Adams

Numerade Educator

Problem 25

An atom of an element has a mass ever so slightly greater than twice the mass of a C atom. Identify the element.

Lottie Adams

Numerade Educator

Problem 26

(a) What is the atomic weight of an element? (b) Why can atomic weights be referred to as relative numbers?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 27

(a) What is the atomic mass unit (amu)? (b) The atomic weight of vanadium is 50.942 amu, and the atomic weight of ruthenium is 101.07 amu. What can we say about the relative masses of V and Ru atoms?

Lottie Adams

Numerade Educator

Problem 28

Determine the formula weight (molecular mass) of each of the following substances: (a) bromine, Br 2; (b) hydrogen peroxide, H2O2; (c) saccharin, C7H 5NSO3; (d) potassium chromate, K2CrO4.

Lottie Adams

Numerade Educator

Problem 29

Determine the formula weight (molecular mass) of each of the following substances: (a) calcium sulfate, CaSO4; (b) propane, C3H 8; (c) the sulfa drug sulfanilamide, C6H 4SO2(NH 2)2; (d) uranyl phosphate, (UO2)3(PO4)2.

Lottie Adams

Numerade Educator

Problem 30

Determine the formula weight (molecular mass) of each of the following common acids: (a) hydrogen sul“de (b) phosphorus trichloride (c) hypochlorous acid (d) hydrogen iodide

Lottie Adams

Numerade Educator

Problem 31

A sample of 6.68 g of calcium combines exactly with 6.33 g of ”uorine, forming calcium ”uoride, CaF 2. Find the relative masses of the atoms of calcium and ”uorine. Check your answer using a table of atomic weights. If the formula were not known, could you still do this calculation?

Lottie Adams

Numerade Educator

Problem 32

Calculate the mass in grams and kilograms of 1.922.

Emily Himsel

Numerade Educator

Problem 33

What mass, in grams, should be weighed for an experiment that requires 1.56 mol of H¬ O¬ O¬ H?

Crystal Wang

Numerade Educator

Problem 34

How many hydrogen atoms are contained in 135 grams of propane?

Crystal Wang

Numerade Educator

Problem 35

(a) How many formula units are contained in 149.3 g of K2CrO4? (b) How many potassium ions? (c) How many CrO4

Crystal Wang

Numerade Educator

Problem 36

How many moles of N.

Emily Himsel

Numerade Educator

Problem 37

A large neon sign is to be “lled with a mixture of gases, including 6.688 g neon. What number of moles is this?

Lijeesh Krishnan

Lijeesh Krishnan

Numerade Educator

Problem 38

How many molecules are in 15.5 g of each of the following substances? (a) CO2; (b) N2; (c) P4; (d) P2. (e) Do parts (c) and (d) contain the same number of atoms of phosphorus?

Crystal Wang

Numerade Educator

Problem 39

Sulfur molecules exist under various conditions as S8, S6, S4, S2, and S. (a) Is the mass of one mole of each of these molecules the same? (b) Is the number of molecules in one mole of each of these molecules the same? (c) Is the mass of sulfur in one mole of each of these molecules the same? (d) Is the number of atoms of sulfur in one mole of each of these molecules the same?

Lottie Adams

Numerade Educator

Problem 40

Complete the following table. Refer to a table of atomic
weights.
Mass of One Mole
Element Atomic Weight of Atoms
(a) Sn ______________ _________________
(b) ________ 79.904 _________________
(c) Mg ______________ _________________
(d) ________ ______________ 51.9961 g

Lottie Adams

Numerade Educator

Problem 41

Complete the following table. Refer to a table of atomic
weights.
Mass of One Mole
Element Formula of Molecules
(a) Br Br2 _________________
(b) ________ O2 _________________
(c) ________ P4 _________________
(d) ________ ________ 20.1797 g
(e) S ________ 256.528 g
(f ) O ________ _________________

Lottie Adams

Numerade Educator

Problem 42

Complete the following table. Moles of Moles of Moles of Compound Cations Anions
1 mol NaClO4 _______________ _______________
2 mol K2SO4 _______________ _______________
0.2 mol calcium sulfate _______________ _______________
_______________ 0.50 mol NH 4 0.25 mol SO4 2

Lottie Adams

Numerade Educator

Problem 43

Calculate the number of Cu atoms in 1.0 trillionth of a gram of copper.

Crystal Wang

Numerade Educator

Problem 44

What is the mass of 8.00 million methane, CH4, molecules?

Crystal Wang

Numerade Educator

Problem 45

A sample of propane, C3H 8, has the same mass as 8.00 million molecules of methane, CH4. How many C3H 8 molecules does the sample contain?

Chareen Guzman

Numerade Educator

Problem 46

Referring to the compounds in Exercise 30, which will contain the largest number of moles of atoms per 100.0 grams of compound?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 47

What percent by mass of iron(II) phosphate is iron?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 48

Calculate the percent by mass of silver found in a particular mineral that is determined to be silver carbonate.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 49

An alcohol is 60.00% C, 13.33% H, and 26.67% O by mass. Another experiment shows that its molecular weight (mass) is approximately 60 amu. What is the molecular formula of the alcohol?

Lottie Adams

Numerade Educator

Problem 50

Skatole is found in coal tar and in human feces. It contains three elements: C, H, and N. It is 82.40% C and 6.92% H by mass. Its simplest formula is its molecular formula. What are (a) the formula and (b) the molecular weight of skatole?

Crystal Wang

Numerade Educator

Problem 51

Testosterone, the male sex hormone, contains only C, H, and O. It is 79.12% C and 9.79% H by mass. Each molecule contains two O atoms. What are (a) the molecular weight and (b) the molecular formula for testosterone?

Crystal Wang

Numerade Educator

Problem 52

The beta-blocker drug, timolol, is expected to reduce the need for heart bypass surgery. Its composition by mass is 49.4% C, 7.64% H, 17.7% N, 15.2% O, and 10.1% S. The mass of 0.0100 mol of timolol is 3.16 g. (a) What is the simplest formula of timolol? (b) What is the molecular formula of timolol?

Lottie Adams

Numerade Educator

Problem 53

Determine the simplest formula for each of the following compounds: (a) copper(II) tartrate: 30.03% Cu, 22.70% C, 1.91% H, 45.37% O; (b) nitrosyl ”uoroborate: 11.99% N, 13.70% O, 9.25% B, 65.06% F.

Crystal Wang

Numerade Educator

Problem 54

The hormone norepinephrine is released in the human body during stress and increases the body•s metabolic rate. Like many biochemical compounds, norepinephrine is composed of carbon, hydrogen, oxygen, and nitrogen. The percent composition of this hormone is 56.8% C, 6.56% H, 28.4% O, and 8.28% N. What is the simplest formula of norepinephrine?

Lottie Adams

Numerade Educator

Problem 55

(a) A sample of a compound is found to contain 5.60 g N, 14.2 g Cl, and 0.800 g H. What is the simplest formula of this compound? (b) A sample of another compound containing the same elements is found to be 26.2% N, 66.4% Cl, and 7.5% H. What is the simplest formula of this compound?

Crystal Wang

Numerade Educator

Problem 56

A common product found in nearly every kitchen contains 27.37% sodium, 1.20% hydrogen, 14.30% carbon, and 57.14% oxygen. The simplest formula is the same as the formula of the compound. Find the formula of this compound.

Crystal Wang

Numerade Educator

Problem 57

Bupropion is present in a medication that is an antidepressant and is also used to aid in quitting smoking. The composition of bupropion is 65.13% carbon, 7.57% hydrogen, 14.79% chlorine, 5.84% nitrogen, and 6.67% oxygen. The simplest formula is the same as the molecular formula.

Crystal Wang

Numerade Educator

Problem 58

Lysine is an essential amino acid. One experiment showed that each molecule of lysine contains two nitrogen atoms. Another experiment showed that lysine contains 19.2% N,
9.64% H, 49.3% C, and 21.9% O by mass. What is the molecular formula for lysine?

Crystal Wang

Numerade Educator

Problem 59

Cocaine has the following percent composition by mass: 67.30% C, 6.930% H, 21.15% O, and 4.62% N. What is the simplest formula of cocaine?

Lottie Adams

Numerade Educator

Problem 60

A compound with the molecular weight of 56.0 g was found as a component of photochemical smog. The compound is composed of carbon and oxygen, 42.9% and 57.1%, respectively. What is the formula of this compound?

Lottie Adams

Numerade Educator

Problem 61

Calculate the percent composition of each of the following compounds: (a) aspartame, C14H 18N 2O5; (b) carborundum, SiC; (c) aspirin, C9H 8O4.

Lottie Adams

Numerade Educator

Problem 62

Calculate the percent composition of each of the following compounds: (a) dopa, C9H 11NO 4; (b) vitamin E, C29H 50O2; (c) vanillin, C8H 8O3.

Lottie Adams

Numerade Educator

Problem 63

Write the chemical formula and the simplest formula of each of the following compounds: (a) hydrogen peroxide, (b) water, (c) ethylene glycol.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 64

Copper is obtained from ores containing the following minerals: azurite, Cu3(CO3)2(OH) 2; chalcocite, Cu2S; chalcopyrite, CuFeS2; covelite, CuS; cuprite, Cu2O; and malachite, Cu2CO3(OH) 2. Which mineral has the lowest copper content as a percent by mass?

Lottie Adams

Numerade Educator

Problem 65

A 1.20-g sample of a compound gave 2.92 g of CO2 and 1.22 g of H2O on combustion in oxygen. The compound is known to contain only C, H, and O. What is its simplest formula?

Lottie Adams

Numerade Educator

Problem 66

A 0.1153-gram sample of a pure hydrocarbon was burned in a C¬ H combustion train to produce 0.3986 gram of CO2 and 0.0578 gram of H2O. Determine the masses of C and H in the sample and the percentages of these elements in this hydrocarbon.

Lottie Adams

Numerade Educator

Problem 67

Naphthalene is a hydrocarbon that is used for mothballs. A 0.3204-gram sample of naphthalene was burned in a C¬ H combustion train to produce 1.100 grams of carbon dioxide and 0.1802 grams of water. What masses and percentages of C and H are present in naphthalene?

Manik Pulyani

Numerade Educator

Problem 68

What is the maximum mass of carbon dioxide that can be produced by the combustion of 0.377 g of

Emily Himsel

Numerade Educator

Problem 69

Complicated chemical reactions occur at hot springs on the ocean ”oor. One compound obtained from such a hot spring consists of Mg, Si, H, and O. From a 0.301-g sample, the Mg is recovered as 0.104 g of MgO; H is recovered as 23.1 mg of H2O; and Si is recovered as 0.155 g of SiO2. What is the simplest formula of this compound?

Crystal Wang

Numerade Educator

Problem 70

A 1.000-gram sample of an alcohol was burned in oxygen to produce 1.913 g of CO2 and 1.174 g of H2O. The alcohol contained only C, H, and O. What is the simplest formula of the alcohol?

Lottie Adams

Numerade Educator

Problem 71

Show that the compounds water, H2O, and hydrogen peroxide, H2O2, obey the Law of Multiple Proportions.

Lottie Adams

Numerade Educator

Problem 72

Nitric oxide, NO, is produced in internal combustion engines. When NO comes in contact with air, it is quickly converted into nitrogen dioxide, NO2, a very poisonous, corrosive gas. What mass of O is combined with 3.00 g of N in (a) NO and (b) NO 2? Show that NO and NO2 obey the Law of Multiple Proportions.

Lottie Adams

Numerade Educator

Problem 73

Sulfur forms two chlorides. A 45.00-gram sample of one chloride decomposes to give 8.30 g of S and 36.71 g of Cl. A 45.00-gram sample of the other chloride decomposes to give 5.90 g of S and 39.11 g of Cl. Show that these compounds obey the Law of Multiple Proportions.

Crystal Wang

Numerade Educator

Problem 74

What mass of oxygen is combined with 9.04 g of sulfur in (a) sulfur dioxide, SO2, and (b) sulfur trioxide, SO3? Interpretation of Chemical Formulas

Lottie Adams

Numerade Educator

Problem 75

One prominent ore of copper contains chalcopyrite, CuFeS2. How many pounds of copper are contained in 6.63 pounds of pure CuFeS2?

Crystal Wang

Numerade Educator

Problem 76

Mercury occurs as a sul“de ore calledcinnabar, HgS. How many grams of mercury are contained in 725 g of pure HgS? A sample of cinnabar

Crystal Wang

Numerade Educator

Problem 77

(a) How many grams of copper are contained in 253 g of CuSO4? (b) How many grams of copper are contained in 253 g of CuSO4 #5H2O?

Crystal Wang

Numerade Educator

Problem 78

What mass of KMnO4 would contain 35.0 g of manganese?

Crystal Wang

Numerade Educator

Problem 79

What mass of azurite, Cu3(CO3)2(OH) 2, would contain 685 g of copper?

Lottie Adams

Numerade Educator

Problem 80

Two minerals that contain copper are chalcopyrite, CuFeS2, and chalcocite, Cu2S. What mass of chalcocite would contain the same mass of copper as is contained in 235 pounds of chalcopyrite?

Crystal Wang

Numerade Educator

Problem 81

Tungsten is a very dense metal (19.3 g/cm3 ) with extremely high melting and boiling points (3370C and 5900C). When a small amount of it is included in steel, the resulting alloy is far harder and stronger than ordinary steel. Two important ores of tungsten are FeWO4 and CaWO4. How many grams of CaWO4 would contain the same mass of tungsten that is present in 625 g of FeWO4?

Crystal Wang

Numerade Educator

Problem 82

When a mole of CuSO4 #5H2O is heated to 110C, it loses four moles of H2O to form CuSO4 $H 2O.$ When it is heated to temperatures above 150C, the other mole of H 2O is lost. (a) How many grams of CuSO4 #H 2O could be obtained by heating 675 g of CuSO4 #5H2O to 110 C? (b) How many grams of anhydrous CuSO4 could be obtained by heating 584 g of CuSO4 #5H2O to 180 C?

Crystal Wang

Numerade Educator

Problem 83

A particular ore of lead, galena, is 10.0% lead sul“de, PbS, and 90.0% impurities by weight. What mass of lead is contained in 110.5 grams of this ore?

Lottie Adams

Numerade Educator

Problem 84

What mass of chromium is present in 345. grams of an ore of chromium that is 55.0% iron(II) dichromate, FeCr2O7, and 45.0% impurities by mass? If 90.0% of the chromium can be recovered from 500.0 grams of the ore, what mass of = pure chromium is obtained?

Crystal Wang

Numerade Educator

Problem 85

What masses of (a) Sr and (b) N are contained in 267.7 g of 88.2% pure Sr(NO3)2? Assume that the impurities do not contain the elements mentioned.

Crystal Wang

Numerade Educator

Problem 86

(a) What weight of magnesium carbonate is contained in 562 pounds of an ore that is 26.7% magnesium carbonate by weight? (b) What weight of impurities is contained in the sample? (c) What weight of magnesium is contained in the sample? (Assume that no magnesium is present in the impurities.)

Crystal Wang

Numerade Educator

Problem 87

Vinegar is 5.0% acetic acid, C2H 4O2, by mass. (a) How many grams of acetic acid are contained in 143.7 g of vinegar? (b) How many pounds of acetic acid are contained in 143.7 pounds of vinegar? (c) How many grams of sodium chloride, NaCl, are contained in 34.0 g of saline solution that is 5.0% NaCl by mass?

Lottie Adams

Numerade Educator

Problem 88

What is the percent by mass of copper sulfate, CuSO4, in a sample of copper sulfate pentahydrate, CuSO4 #5H2O? (b) What is the percent by mass of CuSO4 in a sample that is 74.4% CuSO4 #5H2O by mass?

Crystal Wang

Numerade Educator

Problem 89

Ammonium nitrate, NH 4NO 3, and urea, CH4N 2O, are both commonly used as sources of nitrogen in commercial fertilizers. If ammonium nitrate sells for $$\$2.95/lb$$ and urea for $$\$3.65/lb,$$ which has the more nitrogen for the dollar?

Crystal Wang

Numerade Educator

Problem 90

(a) How many moles of ozone molecules are contained in 96.0 g of ozone, O3? (b) How many moles of oxygen atoms are contained in 96.0 g of ozone? (c) What mass of O2 would contain the same number of oxygen atoms as 96.0 g of ozone? (d) What mass of oxygen gas, O2, would contain the same number of molecules as 96.0 g of ozone?

Lottie Adams

Numerade Educator

Problem 91

The recommended daily dietary allowance of calcium is 1200 mg. Calcium carbonate is an inexpensive source of calcium and useful as a dietary supplement as long as it is taken along with vitamin D which is essential to calcium absorption. How many grams of calcium carbonate must an individual take per day to provide for his/her recommended daily allowance of calcium?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 92

Vitamin E is an antioxidant that plays an especially important role protecting cellular structures in the lungs. Combustion of a 0.497-g sample of vitamin E produced 1.47 g of carbon dioxide and 0.518 g of water. Determine the empirical formula of vitamin E.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 93

A metal, M, forms an oxide having the simplest formula M2O3. This oxide contains 52.9% of the metal by mass. (a) Calculate the atomic weight of the metal. (b) Identify the metal.

Lottie Adams

Numerade Educator

Problem 94

Three samples of magnesium oxide were analyzed to determine the mass ratios O/Mg, giving the following results: Which law of chemical combination is illustrated by these data?

Lottie Adams

Numerade Educator

Problem 95

The molecular weight of hemoglobin is about 65,000 g/ mol. Hemoglobin contains 0.35% Fe by mass. How many iron atoms are in a hemoglobin molecule?

David Collins

Numerade Educator

Problem 96

More than 1 billion pounds of adipic acid (MW 146.1 g/ mol) is manufactured in the United States each year. Most of it is used to make synthetic fabrics. Adipic acid contains only C, H, and O. Combustion of a 1.6380-g sample of adipic acid gives 2.960 g of CO2 and 1.010 g of H2O. (a) What is the simplest formula for adipic acid? (b) What is its molecular formula?

Crystal Wang

Numerade Educator

Problem 97

Crystals of hydroxyapatite, Ca10(PO4)6(OH) 2, provide the hardness associated with bones. In hydroxyapatite crystals, what is (a) the percent calcium and (b) the percent phosphorus?

Lottie Adams

Numerade Educator

Problem 98

If a 2.5-mole sample of each of the following compounds is completely burned, which one would produce the most moles of water? Which would produce the fewest? (a) CH3CH 2OH; (b) CH 3OH; (c) CH 3OCH 3.

Crystal Wang

Numerade Educator

Problem 99

When a sample is burned in a combustion train, the percent oxygen in the sample cannot be determined directly from the mass of water and carbon dioxide formed. Why?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 100

What mass of NaCl would contain the same totalnumber of ions as 365 g of MgCl2?

Crystal Wang

Numerade Educator

Problem 101

Two deposits of minerals containing silver are found. One of the deposits contains silver oxide, and the other contains silver sul“de. The deposits can be mined at the same price per ton of the original silver-containing compound, but only one deposit can be mined by your company. Which of the deposits would you recommend and why?

Crystal Wang

Numerade Educator

Problem 102

A decision is to be made as to the least expensive source of zinc. One source of zinc is zinc sulfate, ZnSO4, and another is zinc acetate dihydrate, Zn(CH3COO) 2 #2H2O. These two sources of zinc can be purchased at the same price per kilogram of compound. Which is the most economical source of zinc and by how much?

Crystal Wang

Numerade Educator

Problem 103

Assume that a penny is 1/16 in. thick and that the moon is 222,000 mi at its closest approach to the earth (perigee). Show by calculation whether or not a picomole of pennies stacked on their faces would reach from the earth to the moon.

Ronald Prasad

Numerade Educator

Problem 104

Find the number of moles of Ag needed to form each ofthe following: (a) 0.8520 mol Ag2S; (b) 0.8520 mol Ag2O; (c) 0.8520 g Ag2S; (d) 8.52 1022 formula units of Ag2S. Building Your Knowledge NOTE: Beginning with this chapter, exercises under the •Building Your KnowledgeŽ heading will often require that you use skills, concepts, or information that you should have mastered in earlier chapters. This provides you an excellent opportunity to •tie things togetherŽ as you study.

Crystal Wang

Numerade Educator

Problem 105

Vegetarians sometimes suffer from the lack of vitamin B12. Each molecule of vitamin B12 contains a single atom of cobalt and is 4.35% cobalt by mass. What is the molecular weight of vitamin B12?

Crystal Wang

Numerade Educator

Problem 106

A student wants to determine the empirical and moleculax formulas of a compound containing only carbon, hydrogen, and oxygen. To do so, he combusted a 0.625 g sample of the compound and formed 1.114 g of CO2 and 0.455 g of water. An independent analysis indicated that the molar mass of the compound is 74.1 g/mol. What are the empirical and molecular formulas of this compound?

Crystal Wang

Numerade Educator

Problem 107

Elemental lead is needed in the construction of storage batteries. The lead is obtained by “rst roasting galena (PbS) in limited air to produce sulfur dioxide and lead oxide. The lead oxide formed is 92.83% lead. The lead is then obtained from the lead oxide in a process that is nearly 100% ef“cient. What is the simplest formula of the lead oxide formed?

Lottie Adams

Numerade Educator

Problem 108

Near room temperature, the density of water is 1.00 g/mL, and the density of ethanol (grain alcohol) is 0.789 g/mL. What volume of ethanol contains the same number of molecules as are present in 225 mL of H2O?

Crystal Wang

Numerade Educator

Problem 109

Use the densities given in Table 1-9 to calculate the molar volume (the volume in L occupied by one mole) for each of the following substances: (a) hydrogen (gas); (b) water; (c) silver.

Crystal Wang

Numerade Educator

Problem 110

Use the molecular volume provided with each compound to calculate its density in grams per mL: (a) NaHCO3, sodium bicarbonate or sodium hydrogen carbonate (also called baking soda), 0.0389 L/mol; (b) I2, iodine, 0.05148 L/mol; (c) Hg, liquid mercury, 0.01476 L/mol; (d) NaCl, common table salt, 0.02699 L/mol. Beyond the Textbook NOTE: Whenever the answer to an exercise depends on information obtained from a source other than this textbook, the source must be included as an essential part of the answer .

Crystal Wang

Numerade Educator

Problem 111

Use an Internet search engine (such as http://www.google .com) to locate the history and properties of the element zinc. When was it “rst isolated? What are three common uses of zinc? Describe the reported effects of a zinc de“-ciency in one•s diet.

Lottie Adams

Numerade Educator

Problem 112

Use an Internet search engine (such as http://www.google .com) to locate the history and properties of the element iodine. When was it “rst isolated? What are three common uses of iodine? Describe three health effects associated with iodine or iodine-containing compounds.

Lottie Adams

Numerade Educator

Problem 113

Use an Internet search engine (such as http://www.google .com) to locate a source of chemistry jokes or puns. Quote a joke or pun that involves the name of an element. Quote a joke or pun that involves a low formula weight compound.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 114

Use an Internet search engine (such as http://www.google .com) to locate the history of Louis Joseph Gay-Lussac. Which element did he discover and isolated.

Lottie Adams

Numerade Educator