General Chemistry: Principles and Modern Applications

Ralph H. Petrucci, F. Geoffrey Herring, Jeffry D. Madura

Chapter 3

Chemical Compounds - all with Video Answers

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Chapter Questions

Problem 1

Refer to the color scheme given in Figure $3-3,$ and give the molecular formulas for the molecules whose balland-stick models are given here.

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Problem 2

Give the molecular formulas for the molecules whose ball-and-stick models are given here. Refer to the color scheme in Figure $3-3$

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Problem 3

Give the structural formulas of the molecules shown in Exercise $1(b),(d),$ and $(e)$

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Problem 4

Give the structural formulas of the molecules shown in Exercise $2(b),(d),$ and $(e)$

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Problem 5

Calculate the total number of (a) atoms in one molecule of trinitrotoluene (TNT), $\mathrm{CH}_{3} \mathrm{C}_{6} \mathrm{H}_{2}\left(\mathrm{NO}_{2}\right)_{3}$ (b) atoms in $0.00102 \mathrm{mol} \mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{2} \mathrm{OH}$ (c) $\mathrm{F}$ atoms in $1215 \mathrm{mol} \mathrm{C}_{2} \mathrm{HBr} \mathrm{ClF}_{3}$

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Problem 6

Determine the mass, in grams, of
(a) $7.34 \mathrm{mol} \mathrm{N}_{2} \mathrm{O}_{4}$
(b) $3.16 \times 10^{24} \mathrm{O}_{2}$ molecules;
(c) $18.6 \mathrm{mol} \mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$
(d) $4.18 \times 10^{24}$ molecules of $\mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{OH})_{2}$

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Problem 7

The amino acid methionine, which is essential in human diets, has the molecular formula $\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{NO}_{2} \mathrm{S}$ Determine (a) its molecular mass; (b) the number of moles of $\mathrm{H}$ atoms per mole of methionine; (c) the number of grams of $C$ per mole of methionine;
(d) the number of $C$ atoms in 9.07 mol methionine.

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Problem 8

Determine the number of moles of $\mathrm{Br}_{2}$ in a sample consisting of
(a) $8.08 \times 10^{22} \mathrm{Br}_{2}$ molecules;
(b) $2.17 \times 10^{24}$ Br atoms;
(c) 11.3 kg bromine;
(d) $2.65 \mathrm{L}$ liquid bromine $(d=3.10 \mathrm{g} / \mathrm{mL})$

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Problem 9

Without doing detailed calculations, explain which of the following has the greatest number of $\mathrm{N}$ atoms (a) $50.0 \mathrm{g}$ $\mathrm{N}_{2} \mathrm{O} ;$ (b) $17.0 \mathrm{g} \mathrm{NH}_{3} ;$ (c) $150 \mathrm{mL}$ of liquid pyridine, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}(d=0.983 \mathrm{g} / \mathrm{mL}) ;$ (d) $1.0 \mathrm{mol} \mathrm{N}_{2}$

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Problem 10

Without doing detailed calculations, determine which of the following has the greatest number of $S$ atoms (a) 0.12 mol of solid sulfur, $S_{8} ;$ (b) 0.50 mol of gaseous $\mathrm{S}_{2} \mathrm{O} ;(\mathrm{c}) 65 \mathrm{g}$ of gaseous $\mathrm{SO}_{2} ;(\mathrm{d}) 75 \mathrm{mL}$ of liquid thiophene, $\mathrm{C}_{4} \mathrm{H}_{4} \mathrm{S}(d=1.064 \mathrm{g} / \mathrm{mL})$

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Problem 11

Determine the number of moles of
(a) $\mathrm{N}_{2} \mathrm{O}_{4}$ in a $115 \mathrm{g}$ sample
(b) $\mathrm{N}$ atoms in $43.5 \mathrm{g}$ of $\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$
(c) $\mathrm{N}$ atoms in a sample of $\mathrm{C}_{7} \mathrm{H}_{5}\left(\mathrm{NO}_{2}\right)_{3}$ that has the same number of $\mathrm{O}$ atoms as $12.4 \mathrm{g} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$

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Problem 12

Determine the mass, in grams, of
(a) $6.25 \times 10^{-2} \mathrm{mol} \mathrm{P}_{4}$
(b) $4.03 \times 10^{24}$ molecules of stearic acid, $\mathrm{C}_{18} \mathrm{H}_{36} \mathrm{O}_{2}$
(c) a quantity of the amino acid lysine, $\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{N}_{2} \mathrm{O}_{2}$ containing 3.03 mol $\mathrm{N}$ atoms

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Problem 13

The hemoglobin content of blood is about $15.5 \mathrm{g} / 100 \mathrm{mL}$ blood. The molar mass of hemoglobin is about $64,500 \mathrm{g} / \mathrm{mol},$ and there are four iron (Fe) atoms in a hemoglobin molecule. Approximately how many Fe atoms are present in the 6 Lof blood in a typical adult?

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Problem 14

In white phosphorus, $P$ atoms are joined into $P_{4}$ molecules (see Figure $3-5$ ). White phosphorus is commonly supplied in chalk-like cylindrical form. Its density is $1.823 \mathrm{g} / \mathrm{cm}^{3}$. For a cylinder of white phosphorus $6.50 \mathrm{cm}$ long and $1.22 \mathrm{cm}$ in diameter, determine
(a) the number of moles of $\mathrm{P}_{4}$ present; (b) the total number of $\mathrm{P}$ atoms.

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Problem 15

Explain which of the following statement(s) is (are) correct concerning glucose (blood sugar), $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$
(a) The percentages, by mass, of $\mathrm{C}$ and $\mathrm{O}$ are the same as in CO.
(b) The ratio of $\mathrm{C}: \mathrm{H}: \mathrm{O}$ atoms is the same as in dihydroxyacetone, $\left(\mathrm{CH}_{2} \mathrm{OH}\right)_{2} \mathrm{CO}$
(c) The proportions, by mass, of $C$ and $O$ are equal.
(d) The highest percentage, by mass, is that of H.

Susan Hallstrom

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Problem 16

Explain which of the following statement(s) is (are) correct for sorbic acid, $\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{2},$ an inhibitor of mold and yeast.
(a) It has a $\mathrm{C}: \mathrm{H}:$ O mass ratio of 3: 4: 1
(b) It has the same mass percent composition as the aquatic herbicide, acrolein, $\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{O}$
(c) It has the same empirical formula as aspidinol, $\mathrm{C}_{12} \mathrm{H}_{16} \mathrm{O}_{4},$ a drug used to kill parasitic worms.
(d) It has four times as many $\mathrm{H}$ atoms as $\mathrm{O}$ atoms, but four times as much O as H by mass.

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Problem 17

For the mineral torbernite, $\mathrm{Cu}\left(\mathrm{UO}_{2}\right)_{2}\left(\mathrm{PO}_{4}\right)_{2} \cdot 8 \mathrm{H}_{2} \mathrm{O}$ determine
(a) the total number of atoms in one formula unit
(b) the ratio, by number, of $\mathrm{H}$ atoms to $\mathrm{O}$ atoms
(c) the ratio, by mass, of $\mathrm{Cu}$ to $\mathrm{P}$
(d) the element present in the greatest mass percent
(e) the mass required to contain $1.00 \mathrm{g} \mathrm{P}$

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Problem 18

For the compound $\operatorname{Ge}\left[\mathrm{S}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{3}\right]_{4},$ determine
(a) the total number of atoms in one formula unit
(b) the ratio, by number, of C atoms to H atoms
(c) the ratio, by mass, of Ge to $S$
(d) the number of $g$ S in 1 mol of the compound
(e) the number of $C$ atoms in 33.10 g of the compound

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Problem 19

Determine the mass percent $\mathrm{H}$ in the hydrocarbon decane, $\mathrm{C}_{10} \mathrm{H}_{22}$

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Problem 20

Determine the mass percent $O$ in the mineral malachite, $\mathrm{Cu}_{2}(\mathrm{OH})_{2} \mathrm{CO}_{3}$

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Problem 21

Determine the mass percent $H$ in the hydrocarbon isooctane, $\mathrm{C}\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}$

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Problem 22

Determine the mass percent $\mathrm{H}_{2} \mathrm{O}$ in the hydrate $\mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3} \cdot 9 \mathrm{H}_{2} \mathrm{O}$

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Problem 23

Determine the mass percent of each of the elements in the antimalarial drug quinine, $\mathrm{C}_{20} \mathrm{H}_{24} \mathrm{N}_{2} \mathrm{O}_{2}$

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Problem 24

Determine the mass percent of each of the elements in the fungicide copper(II) oleate, $\mathrm{Cu}\left(\mathrm{C}_{18} \mathrm{H}_{33} \mathrm{O}_{2}\right)_{2}$

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Problem 25

Determine the percent, by mass, of the indicated element:
(a) $\mathrm{Pb}$ in tetraethyl lead, $\mathrm{Pb}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{4},$ once extensively used as an additive to gasoline to prevent engine knocking
(b) Fe in Prussian blue, $\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3},$ a pigment used in paints and printing inks
(c) $\mathrm{Mg}$ in chlorophyll, $\mathrm{C}_{55} \mathrm{H}_{72} \mathrm{MgN}_{4} \mathrm{O}_{5},$ the green
pigment in plant cells

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Problem 26

All of the following minerals are semiprecious or precious stones. Determine the mass percent of the indicated element.
(a) $\mathrm{Zr}$ in zircon, $\mathrm{ZrSiO}_{4}$
(b) Be in beryl (emerald), $\mathrm{Be}_{3} \mathrm{Al}_{2} \mathrm{Si}_{6} \mathrm{O}_{18}$
(c) Fe in almandine (garnet), $\mathrm{Fe}_{3} \mathrm{Al}_{2} \mathrm{Si}_{3} \mathrm{O}_{12}$
(d) S in lazurite (lapis lazuli), $\mathrm{Na}_{4} \mathrm{SSi}_{3} \mathrm{Al}_{3} \mathrm{O}_{12}$

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Problem 27

Without doing detailed calculations, arrange the following in order of increasing $\% \mathrm{Cr},$ by mass, and explain your reasoning: $\mathrm{CrO}, \mathrm{Cr}_{2} \mathrm{O}_{3}, \mathrm{CrO}_{2}, \mathrm{CrO}_{3}$

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Problem 28

Without doing detailed calculations, explain which of the following has the greatest mass percent of sulfur. $\mathrm{SO}_{2}, \mathrm{S}_{2} \mathrm{Cl}_{2}, \mathrm{Na}_{2} \mathrm{S}, \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}, \mathrm{or} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{SH}$

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Problem 29

Two oxides of sulfur have nearly identical molecular masses. One oxide consists of $40.05 \%$ S. What are the simplest possible formulas for the two oxides?

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Problem 30

An oxide of chromium used in chrome plating has a formula mass of $100.0 \mathrm{u}$ and contains bur atoms per formula unit. Establish the formula of this compound with a minimum ofcalculation.

Dr. Satish Ingale

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Problem 31

Diethylene glycol, used to deice aircraft, is a carbonhydrogen-oxygen compound with $45.27 \%$ C and $9.50 \%$ H by mass. What is its empirical formula?

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Problem 32

The food flavor enhancer monosodium glutamate (MSG) has the composition $13.6 \%$ Na, $35.5 \%$ C. $4.8 \% \mathrm{H}, 8.3 \% \mathrm{N}, 37.8 \% \mathrm{O},$ by mass. What is the empirical formula of MSG?

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Problem 33

Determine the empirical formula of (a) the rodenticide (rat killer) warfarin, which consists of $74.01 \% \mathrm{C}$ $5.23 \% \mathrm{H},$ and $20.76 \%$ O, by mass; (b) the antibacterial agent sulfamethizole, which consists of $39.98 \%$ C. $3.73 \% \mathrm{H}, 20.73 \% \mathrm{N}, 11.84 \% \mathrm{O},$ and $23.72 \% \mathrm{S},$ by mass.

Dr. Satish Ingale

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Problem 34

Determine the empirical formula of (a) benzo-[a]pyrene, a suspected carcinogen found in cigarette smoke, consisting of $95.21 \%$ C and $4.79 \%$ H, by mass; (b) hexachlorophene, used in germicidal soaps, which consists of $38.37 \%$ C $, 1.49 \%$ H, $52.28 \%$ Cl, and $7.86 \%$ O by mass.

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Problem 35

A compound of carbon and hydrogen consists of $94.34 \% \mathrm{C}$ and $5.66 \% \mathrm{H},$ by mass. The molecular mass of the compound is found to be 178 u. What is its molecular formula?

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Problem 36

Selenium, an element used in the manufacture of photoelectric cells and solar energy devices, forms two oxides. One has $28.8 \%$ O, by mass, and the other, 37.8\% O. What are the formulas of these oxides? Propose acceptable names for them.

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Problem 37

Indigo, the dye for blue jeans, has a percent composition, by mass, of $73.27 \%$ C $, 3.84 \%$ H, $10.68 \%$ N, and the remainder is oxygen. The molecular mass of indigo is 262.3 u. What is the molecular formula of indigo?

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Problem 38

Adenine, a component of nucleic acids, has the mass percent composition: $44.45 \%$ C $, 3.73 \%$ H, $51.82 \%$ N. Its molecular mass is 135.14 u. What is its molecular formula?

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Problem 39

The element $X$ forms the chloride $X C l_{4}$ containing $75.0 \% \mathrm{Cl},$ by mass. What is element $\mathrm{X} ?$

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Problem 40

The element $X$ forms the compound $X O C l_{2}$ containing 59.6\% Cl. What is element X?

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Problem 41

Chlorophyll contains $2.72 \%$ Mg by mass. Assuming one Mg atom per chlorophyll molecule, what is the molecular mass of chlorophyll?

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Problem 42

Two compounds of $\mathrm{Cl}$ and $\mathrm{X}$ are found to have molecular masses and \% Cl, by mass, as follows: 137 u, $77.5 \% \mathrm{Cl} ; 208 \mathrm{u}, 85.1 \%$ Cl. What is element $\mathrm{X} ?$ What is the formula for each compound?

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Problem 43

A $0.1888 \mathrm{g}$ sample of a hydrocarbon produces $0.6260 \mathrm{g}$ $\mathrm{CO}_{2}$ and $0.1602 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$ in combustion analysis. Its molecular mass is found to be 106 u. For this hydrocarbon, determine its (a) mass percent composition; (b) empirical formula; (c) molecular formula.

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Problem 44

Para-cresol ( $p$ -cresol) is used as a disinfectant and in the manufacture of herbicides. A 0.4039 g sample of this carbon-hydrogen-oxygen compound yields $1.1518 \mathrm{g} \mathrm{CO}_{2}$ and $0.2694 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$ in combustion analysis. Its molecular mass is 108.1 u. For $p$ -cresol, determine its (a) mass percent composition; (b) empirical formula; (c) molecular formula.

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Problem 45

Dimethylhydrazine is a carbon-hydrogen-nitrogen compound used in rocket fuels. When burned in an excess of oxygen, a $0.312 \mathrm{g}$ sample yields $0.458 \mathrm{g} \mathrm{CO}_{2}$ and $0.374 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$. The nitrogen content of a $0.486 \mathrm{g}$ sample is converted to $0.226 \mathrm{g} \mathrm{N}_{2} .$ What is the empirical formula of dimethylhydrazine?

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Problem 46

The organic solvent thiophene is a carbon-hydrogensulfur compound that yields $\mathrm{CO}_{2}, \mathrm{H}_{2} \mathrm{O},$ and $\mathrm{SO}_{2}$ when burned in an excess of oxygen. When subjected to combustion analysis, a $1.3020 \mathrm{g}$ sample of thiophene produces $2.7224 \mathrm{g} \mathrm{CO}_{2}, 0.5575 \mathrm{g} \mathrm{H}_{2} \mathrm{O},$ and $0.9915 \mathrm{g} \mathrm{SO}_{2} .$ What is the empirical formula of thiophene?

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Problem 47

Without doing detailed calculations, explain which of these compounds produces the greatest mass of $\mathrm{CO}_{2}$ when $1.00 \mathrm{mol}$ of the compound is burned in an excess of $\mathrm{H}_{4}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, \mathrm{C}_{10} \mathrm{H}_{8}, \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}$

Natalie Almond

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Problem 48

Without doing detailed calculations, explain which of these compounds produces the greatest mass of $\mathrm{H}_{2} \mathrm{O}$ when $1.00 \mathrm{g}$ of the compound is burned in an excess of oxygen: $\mathrm{CH}_{4}, \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}, \mathrm{C}_{10} \mathrm{H}_{8}, \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}$

Katherine Mccandless

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Problem 49

A $1.562 \mathrm{g}$ sample of the alcohol $\mathrm{CH}_{3} \mathrm{CHOHCH}_{2} \mathrm{CH}_{3}$ is burned in an excess of oxygen. What masses of $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ should be obtained?

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Problem 50

Liquid ethyl mercaptan, $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{S},$ has a density of $0.84 \mathrm{g} / \mathrm{mL} .$ Assuming that the combustion of this compound produces only $\mathrm{CO}_{2}, \mathrm{H}_{2} \mathrm{O},$ and $\mathrm{SO}_{2},$ what masses of each of these three products would be produced in the combustion of $3.15 \mathrm{mL}$ of ethyl mercaptan?

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Problem 51

Indicate the oxidation state of the underlined element in (a) $\mathrm{CH}_{4} ;$ (b) $\mathrm{SF}_{4}$ (c) $\mathrm{Na}_{2} \mathrm{O}_{2}$ (d) $\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}^{-}$ (e) $\mathrm{FeO}_{4}^{2-}$

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Problem 52

Indicate the oxidation state of $S$ in $\left(\text { a) } \mathrm{SO}_{3}^{2-}\right.$ (b) $\mathrm{S}_{2} \mathrm{O}_{3}^{2-} ;$ (c) $\mathrm{S}_{2} \mathrm{O}_{8}^{2-} ;$ (d) $\mathrm{HSO}_{4}^{-} ;$ (e) $\mathrm{S}_{4} \mathrm{O}_{6}^{2-}$

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Problem 53

Chromium forms three principal oxides. Write appropriate formulas for these compounds in which the oxidation states of Cr are $+3,+4,$ and $+6,$ respectively.

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Problem 54

Nitrogen forms five oxides in which its oxidation states are $+1,+2,+3,+4,$ and $+5,$ respectively. Write appropriate formulas for these compounds.

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Problem 55

In many of its compounds, oxygen has an oxidation state of $-2 .$ However, there are exceptions. What is the oxidation state of oxygen in each of the following compounds? (a) $\mathrm{OF}_{2} ;$ (b) $\mathrm{O}_{2} \mathrm{F}_{2} ;$ (c) $\mathrm{CsO}_{2}$; (d) $\mathrm{BaO}_{2}$

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Problem 56

Hydrogen and oxygen usually have oxidation states of +1 and $-2,$ respectively, in their compounds. The following cases serve to remind us that there are exceptions. What are the oxidation states of the atoms in each of the following compounds? (a) $\mathrm{MgH}_{2}$ (b) $\mathrm{CsO}_{3} ;$ (c) HOF; (d) $\mathrm{NaAlH}_{4}$

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Problem 57

Name these compounds: (a) $\operatorname{SrO} ;$ (b) $\mathrm{ZnS} ;$ (c) $\mathrm{K}_{2} \mathrm{CrO}_{4}$ (d) $\mathrm{Cs}_{2} \mathrm{SO}_{4} ;(\mathrm{e}) \mathrm{Cr}_{2} \mathrm{O}_{3} ;(\mathrm{f}) \mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3} ;(\mathrm{g}) \mathrm{Mg}\left(\mathrm{HCO}_{3}\right)_{2}$ (h) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4} ; \quad$ (i) $\quad \mathrm{Ca}\left(\mathrm{HSO}_{3}\right)_{2} ; \quad(\mathrm{j}) \quad \mathrm{Cu}(\mathrm{OH})_{2}$ (k) $\mathrm{HNO}_{3} ;$ (1) $\mathrm{KClO}_{4} ;$ (m) $\mathrm{HBrO}_{3} ;$ (n) $\mathrm{H}_{3} \mathrm{PO}_{3}$.

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Problem 58

Name these compounds: (a) $\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2} ;$ (b) $\mathrm{HNO}_{2}$; (c) $\operatorname{Cr} \mathrm{O}_{2} ;$ (d) $\mathrm{KIO}_{3} ;$ (e) $\mathrm{LiCN} ;$ (f) $\mathrm{KIO} ;$ (g) $\mathrm{Fe}(\mathrm{OH})_{2}$
(h) $\mathrm{Ca}\left(\mathrm{H}_{2} \mathrm{PO}_{4}\right)_{2} ;$ (i) $\mathrm{H}_{3} \mathrm{PO}_{4} ;$ (j) $\mathrm{NaHSO}_{4} ;$ (k) $\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$; (l) $\mathrm{NH}_{4} \mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2} ;(\mathrm{m}) \mathrm{MgC}_{2} \mathrm{O}_{4} ;$ (n) $\mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$

Natalie Almond

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Problem 59

Assign suitable names to the compounds (a) $\mathrm{CS}_{2}$ (b) $\operatorname{SiF}_{4} ;$ (c) $\operatorname{ClF}_{5} ;$ (d) $\mathrm{N}_{2} \mathrm{O}_{5} ;$ (e) $\mathrm{SF}_{6} ;$ (f) $\mathrm{I}_{2} \mathrm{Cl}_{6}$.

Natalie Almond

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Problem 60

Assign suitable names to the compounds (a) ICl; (b) $\mathrm{ClF}_{3} ;$ (c) $\mathrm{SF}_{4} ;$ (d) $\mathrm{Br} \mathrm{F}_{5} ;$ (e) $\mathrm{N}_{2} \mathrm{O}_{4} ;$ (f) $\mathrm{S}_{4} \mathrm{N}_{4}$.

Vasu Makani

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Problem 61

Write formulas for the compounds: (a) aluminum sulfate; (b) ammonium dichromate; (c) silicon tetrafluoride;
(d) iron(III) oxide; (e) tricarbon disulfide; (f) cobalt(II) nitrate; (g) strontium nitrite; (h) hydrobromic acid;
(i) iodic acid; (j) phosphorus dichloride trifluoride.

Natalie Almond

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Problem 62

Write formulas for the compounds: (a) magnesium perchlorate; (b) lead(II) acetate; (c) tin(IV) oxide;
(d) hydroiodic acid; (e) chlorous acid; (f) sodium hydrogen sulfite; (g) calcium dihydrogen phosphate;
(h) aluminum phosphate; (i) dinitrogen tetroxide;
(j) disulfur dichloride.

Natalie Almond

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Problem 63

Write a formula for (a) the chloride of titanium having Ti in the O.S. $+4 ;$ (b) the sulfate of iron having Fe in the O.S. $+3 ;(c)$ an oxide of chlorine with Cl in the O.S. $+7 ;$ (d) an oxoanion of sulfur in which the apparent O.S. of $S$ is +7 and the ionic charge is $2-$.

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Problem 64

Write a formula for (a) an oxide of nitrogen with $\mathrm{N}$ in the O.S. $+5 ;$ (b) an oxoacid of nitrogen with $\mathrm{N}$ in the O.S. $+3 ;$ (c) an oxide of carbon in which the apparent O.S. of $C$ is $+4 / 3 ;$ (d) a sulfur-containing oxoanion in which the apparent O.S. of $S$ is +2.5 and the ionic charge is $2-$.

Katherine Mccandless

Katherine Mccandless

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Problem 65

Name the acids: (a) $\mathrm{HClO}_{2} ;$ (b) $\mathrm{H}_{2} \mathrm{SO}_{3} ;$ (c) $\mathrm{H}_{2} \mathrm{Se}$ (d) HNO $_{2}$.

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Problem 66

Supply the formula for the acids: (a) hydrofluoric acid; (b) nitric acid; (c) phosphorous acid; (d) sulfuric acid.

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Problem 67

Name the following compounds and specify which ones are best described as ionic: (a) $\mathrm{OF}_{2} ;$ (b) $\mathrm{XeF}_{2}$ (c) $\operatorname{CuSO}_{3} ;$ (d) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}$

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Problem 68

Name the following compounds and specify which ones are best described as ionic: (a) $\mathrm{KNO}_{2} ;$ (b) $\mathrm{Br} \mathrm{F}_{3}$ (c) $\mathrm{S}_{2} \mathrm{Cl}_{2} ;$ (d) $\mathrm{Mg}(\mathrm{ClO})_{2} ;$ (e) $\mathrm{Cl}_{2} \mathrm{O}$

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Problem 69

Without per frming detailed calculations, indicate which of the following hydrates has the greatest \% $\mathrm{H}_{2} \mathrm{O}$ by mass: $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}, \quad \mathrm{Cr}_{2}\left(\mathrm{SO}_{4}\right)_{3} \cdot 18 \mathrm{H}_{2} \mathrm{O}, \quad \mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ and $\mathrm{LiC}_{2} \mathrm{H}_{3} \mathrm{O}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$

Dr. Satish Ingale

Dr. Satish Ingale

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Problem 70

Without per forming detailed calculations, determine the hydrate of $\mathrm{Na}_{2} \mathrm{SO}_{3}$ that contains almost exactly $50 \%$ $\mathrm{H}_{2} \mathrm{O},$ by mass.

Vasu Makani

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Problem 71

Anhydrous $\mathrm{CuSO}_{4}$ can be used to dry liquids in which it is insoluble. The CuSO $_{4}$ is converted to $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ which can be filtered off from the liquid. What is the minimum mass of anhydrous $\mathrm{CuSO}_{4}$ needed to remove $12.6 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$ from a tankful of gasoline?

Natalie Almond

Numerade Educator

Problem 72

Anhydrous sodium sulfate, $\mathrm{Na}_{2} \mathrm{SO}_{4},$ absorbs water vapor and is converted to the decahydrate, $\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot 10 \mathrm{H}_{2} \mathrm{O} .$ How much would the mass of $24.05 \mathrm{g}$ of anhydrous $\mathrm{Na}_{2} \mathrm{SO}_{4}$ increase if converted completely to the decahydrate?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 73

A certain hydrate is found to have the composition $20.3 \%$ Cu, $8.95 \%$ Si, $36.3 \%$ F, and $34.5 \% \mathrm{H}_{2} \mathrm{O}$ by mass. What is the empirical formula of this hydrate?

Natalie Almond

Numerade Educator

Problem 74

An 8.129 g sample of $\mathrm{MgSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}$ is heated until all the water of hydration is driven off. The resulting anhydrous compound, $\mathrm{MgSO}_{4},$ weighs $3.967 \mathrm{g} .$ What is the formula of the hydrate?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 75

Which of the following names is most appropriate for the molecule with the structure shown below? (a) butyl alcohol; (b) 2-butanol; (c) 1-butanol; (d) isopentyl alcohol.

Vasu Makani

Numerade Educator

Problem 76

Which of the following names is most appropriate for the molecule $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{2} \mathrm{COOH} ?$ (a) dimethyleneacetic acid; (b) propanoic acid; (c) butanoic acid; (d) oxobutylalcohol.

Natalie Almond

Numerade Educator

Problem 77

Which of the following structures are isomers?

Alkendra Singh

Numerade Educator

Problem 78

Which of the following structures are isomers?

Alkendra Singh

Numerade Educator

Problem 79

Write the condensed structural formulas for the organic compounds:
(a) heptane
(b) propanoic acid
(c) 2-methyl-1-pentanol
(d) fluoroethane

Vasu Makani

Numerade Educator

Problem 80

Write the condensed structural formulas for the organic compounds:
(a) octane
(b) heptanoic acid
(c) 3-hexanol
(d) 2 -chlorobutane

Vasu Makani

Numerade Educator

Problem 81

Give the name, condensed structural formula, and molecular mass of the molecule whose ball-and-stick model is shown. Refer to the color scheme in Figure $3-3$

Andrew Jensen

Numerade Educator

Problem 82

Give the name, condensed structural formula, and molecular mass of the molecule whose ball-and-stick model is shown. Refer to the color scheme in Figure $3-3$

Andrew Jensen

Numerade Educator

Problem 83

The mineral spodumene has the empirical formula $\mathrm{LiAlSi}_{2} \mathrm{O}_{6} .$ Given that the percentage of lithium- 6 atoms in naturally occuring lithium is $7.40 \%,$ how many lithium- 6 atoms are present in a 518 g sample of spodumene?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 84

A particular type of brass contains $\mathrm{Cu}, \mathrm{Sn}, \mathrm{Pb},$ and Zn. A $1.1713 \mathrm{g}$ sample is treated in such a way as to convert the Sn to $0.245 \mathrm{g} \mathrm{SnO}_{2}$, the $\mathrm{Pb}$ to $0.115 \mathrm{g}$ $\mathrm{PbSO}_{4},$ and the $\mathrm{Zn}$ to $0.246 \mathrm{g} \mathrm{Zn}_{2} \mathrm{P}_{2} \mathrm{O}_{7} .$ What is the mass percent of each element in the sample?

Natalie Almond

Numerade Educator

Problem 85

A brand of lunchmeat contains $0.10 \%$ by mass of sodium benzoate, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COONa} .$ How many $\mathrm{mg}$ of Na does a person ingest by eating 2.52 oz of this meat?

Pam Owens

Numerade Educator

Problem 86

The important natural sources of boron compounds are the minerals kernite, $\mathrm{Na}_{2} \mathrm{B}_{4} \mathrm{O}_{7} \cdot 4 \mathrm{H}_{2} \mathrm{O}$ and borax, $\mathrm{Na}_{2} \mathrm{B}_{4} \mathrm{O}_{7} \cdot 10 \mathrm{H}_{2} \mathrm{O} .$ How much additional mass of mineral must be processed per kilogram of boron obtained if the mineral is borax rather than kernite?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 87

To deposit exactly one mole of $\mathrm{Ag}$ from an aqueous solution containing $\mathrm{Ag}^{+}$ requires a quantity of electricity known as one faraday (F). The electrodeposition requires that each $\mathrm{Ag}^{+}$ ion gain one electron to become an Ag atom. Use appropriate physical constants listed on the inside back cover to obtain a precise value of the Avogadro constant, $N_{A}$.

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 88

By analysis, a compound was found to contain $26.58 \% \mathrm{K}$ and $35.45 \% \mathrm{Cr}$ by mass; the remainder was oxygen. What is the oxidation state of chromium in this compound? What is the name of the compound?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 89

Is it possible to have a sample of $S_{8}$ that weighs $1.00 \times 10^{-23} \mathrm{g} ?$ What is the smallest possible mass that a sample of $S_{8}$ can have? Express your answer to the second question in appropriate SI units so that your answer has a numerical value greater than 1 (See Table 1.2 for a list of SI prefixes.)

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 90

What is the molecular formula of a hydrocarbon containing $n$ carbon atoms and only one double bond? Can such a hydrocarbon yield a greater mass of $\mathrm{H}_{2} \mathrm{O}$ than $\mathrm{CO}_{2}$ when burned in an excess of oxygen?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 91

A hydrocarbon mixture consists of $60.0 \%$ by mass of $\mathrm{C}_{3} \mathrm{H}_{8}$ and $40.0 \%$ of $\mathrm{C}_{x} \mathrm{H}_{y} .$ When $10.0 \mathrm{g}$ of this mixture is burned, $29.0 \mathrm{g} \mathrm{CO}_{2}$ and $18.8 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$ are the only products. What is the formula of the unknown hydrocarbon?

Natalie Almond

Numerade Educator

Problem 92

A 0.732 g mixture of methane, $\mathrm{CH}_{4}$, and ethane, $\mathrm{C}_{2} \mathrm{H}_{6},$ is burned, yielding $2.064 \mathrm{g} \mathrm{CO}_{2} .$ What is the percent composition of this mixture (a) by mass; (b) on a mole basis?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 93

The density of a mixture of $\mathrm{H}_{2} \mathrm{SO}_{4}$ and water is 1.78 g/mL. The percent composition of the mixture is to be determined by converting $\mathrm{H}_{2} \mathrm{SO}_{4}$ to $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ If $32.0 \mathrm{mL}$ of the mixture gives $65.2 \mathrm{g}\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ then what is the percent composition of the mixture?

David Collins

Numerade Educator

Problem 94

All the silver in a $26.39 \mathrm{g}$ sample of impure silver is converted to silver chloride. If 31.56 g of silver chloride are obtained, then what is the mass percent of silver in the sample?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 95

In the year 2000 , the Guinness Book of World Records called ethyl mercaptan, $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{S}$, the smelliest substance known. The average person can detect its presence in air at levels as low as $9 \times 10^{-4} \mu \mathrm{mol} / \mathrm{m}^{3} .$ Express the limit of detectability of ethyl mercaptan in parts per billion (ppb). (Note: 1 ppb $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{S}$ means there is $1 \mathrm{g}$ $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{S}$ per billion grams of air.) The density of air is approximately $1.2 \mathrm{g} / \mathrm{L}$ at room temperature.

David Collins

Numerade Educator

Problem 96

Dry air is essentially a mixture of the following entities: $\mathrm{N}_{2}, \mathrm{O}_{2}, \mathrm{Ar},$ and $\mathrm{CO}_{2} .$ The composition of dry air, in mole percent, is $78.08 \% \mathrm{N}_{2}, 20.95 \% \mathrm{O}_{2}, 0.93 \% \mathrm{Ar}$ and $0.04 \% \mathrm{CO}_{2}$. (a) What is the mass, in grams, of a sample of air that contains exactly one mole of the entities? (b) Dry air also contains other entities in much smaller amounts. For example, the mole percent of krypton (Kr) is about $1.14 \times 10^{-4} \% .$ Given that the density of dry air is about $1.2 \mathrm{g} / \mathrm{L}$ at room temperature, what mass of krypton could be obtained from exactly one cubic meter of dry air?

David Collins

Numerade Educator

Problem 97

A public water supply was found to contain 1 part per billion (ppb) by mass of chloroform, $\mathrm{CHCl}_{3}$ (a) How many $\mathrm{CHCl}_{3}$ molecules would be present in a $225 \mathrm{mL}$ glass of this water? (b) If the $\mathrm{CHCl}_{3}$ in part (a) could be isolated, would this quantity be detectable on an ordinary analytical balance that measures mass with a precision of ±0.0001 g?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 98

A sample of the compound MSO $_{4}$ weighing $0.1131 \mathrm{g}$ reacts with barium chloride and yields $0.2193 \mathrm{g} \mathrm{BaSO}_{4}$ What must be the atomic mass of the metal M? [Hint: All the $\mathrm{SO}_{4}^{2-}$ from the MSO $_{4}$ appears in the $\mathrm{BaSO}_{4}$ ]

David Collins

Numerade Educator

Problem 99

The metal M forms the sulfate $\mathrm{M}_{2}\left(\mathrm{SO}_{4}\right)_{3} .$ A $0.738 \mathrm{g}$ sample of this sulfate is converted to $1.511 \mathrm{g} \mathrm{BaSO}_{4}$ What is the atomic mass of M? [Hint: Refer to Exercise 98.]

David Collins

Numerade Educator

Problem 100

A 0.622 g sample of a metal oxide with the formula $\mathrm{M}_{2} \mathrm{O}_{3}$ is converted to $0.685 \mathrm{g}$ of the sulfide, MS. What is the atomic mass of the metal M?

Natalie Almond

Numerade Educator

Problem 101

$\mathrm{MgCl}_{2}$ often occurs in table salt $(\mathrm{NaCl})$ and is responsible for caking of the salt. A 0.5200 g sample of table salt is found to contain $61.10 \%$ Cl, by mass. What is the $\% \mathrm{MgCl}_{2}$ in the sample? Why is the precision of this calculation so poor?

David Collins

Numerade Educator

Problem 102

When $2.750 \mathrm{g}$ of the oxide of lead $\mathrm{Pb}_{3} \mathrm{O}_{4}$ is strongly heated, it decomposes and produces $0.0640 \mathrm{g}$ of oxygen gas and $2.686 \mathrm{g}$ of a second oxide of lead. What is the empirical formula of this second oxide?

Anand Jangid

Numerade Educator

Problem 103

A $1.013 \mathrm{g}$ sample of $\mathrm{ZnSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}$ is dissolved in water and the sulfate ion precipitated as $\mathrm{BaSO}_{4}$. The mass of pure, dry $\mathrm{BaSO}_{4}$ obtained is $0.8223 \mathrm{g}$. What is the formula of the zinc sulfate hydrate?

Anna D.

Numerade Educator

Problem 104

The iodide ion in a $1.552 \mathrm{g}$ sample of the ionic compound MI is removed through precipitation. The precipitate is found to contain $1.186 \mathrm{g}$ I. What is the element M?

Ronald Prasad

Numerade Educator

Problem 105

An oxoacid with the formula $\mathrm{H}_{x} \mathrm{E}_{y} \mathrm{O}_{z}$ has a formula mass of 178 u, has 13 atoms in its formula unit, contains $34.80 \%$ by mass, and $15.38 \%$ by number of atoms, of the element E. What is the element $\mathrm{E}$, and what is the formula of this oxoacid?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 106

The insecticide dieldrin contains carbon, hydrogen, oxygen, and chlorine. When burned in an excess of oxygen, a 1.510 g sample yields $2.094 \mathrm{g} \mathrm{CO}_{2}$ and $0.286 \mathrm{g} \mathrm{H}_{2} \mathrm{O} .$ The compound has a molecular mass of 381 u and has half as many chlorine atoms as carbon atoms. What is the molecular formula of dieldrin?

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 107

A thoroughly dried 1.271 g sample of $\mathrm{Na}_{2} \mathrm{SO}_{4}$ is exposed to the atmosphere and found to gain $0.387 \mathrm{g}$ in mass. What is the percent, by mass, of $\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot 10 \mathrm{H}_{2} \mathrm{O}$ in the resulting mixture of anhydrous $\mathrm{Na}_{2} \mathrm{SO}_{4}$ and the decahydrate?

David Collins

Numerade Educator

Problem 108

The atomic mass of $\mathrm{Bi}$ is to be determined by converting the compound $\mathrm{Bi}\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{3}$ to $\mathrm{Bi}_{2} \mathrm{O}_{3} .$ If $5.610 \mathrm{g}$ of $\mathrm{Bi}\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{3}$ yields $2.969 \mathrm{g} \mathrm{Bi}_{2} \mathrm{O}_{3},$ what is the atomic mass of Bi?

David Collins

Numerade Educator

Problem 109

A piece of gold (Au) foil measuring $0.25 \mathrm{mm} \times$ $15 \mathrm{mm} \times 15 \mathrm{mm}$ is treated with fluorine gas. The treatment converts all the gold in the foil to $1.400 \mathrm{g}$ of a gold fluoride. What is the formula and name of the fluoride? The density of gold is $19.3 \mathrm{g} / \mathrm{cm}^{3}$

David Collins

Numerade Educator

Problem 110

In an experiment, $244 \mathrm{mL}$ of chlorine gas $\left(\mathrm{Cl}_{2}, d=2.898 \mathrm{g} / \mathrm{L}\right)$ combines with iodine to give $1.553 \mathrm{g}$ of a binary compound. In a separate experiment, the molar mass of the compound is found to be about $467 \mathrm{g} / \mathrm{mol} .$ What is the molecular formula of this compound?

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 111

All-purpose fertilizers contain the essential elements nitrogen, phosphorus, and potassium. A typical fertilizer carries numbers on its label, such as "5-10-5". These numbers represent the \% $\mathrm{N}, \% \mathrm{P}_{2} \mathrm{O}_{5},$ and $\% \mathrm{K}_{2} \mathrm{O},$ respectively. The $\mathrm{N}$ is contained in the form of a nitrogen compound, such as $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}, \mathrm{NH}_{4} \mathrm{NO}_{3}$
or $\mathrm{CO}\left(\mathrm{NH}_{2}\right)_{2}$ (urea). The $\mathrm{P}$ is generally present as a phosphate, and the $K$ as $K C$. The expressions $\% \mathrm{P}_{2} \mathrm{O}_{5}$ and $\% \mathrm{K}_{2} \mathrm{O}$ were devised in the nineteenth century, before the nature of chemical compounds was fully understood. To convert from \% $\mathrm{P}_{2} \mathrm{O}_{5}$ to \% $\mathrm{P}$ and from \% $\mathrm{K}_{2} \mathrm{O}$ to \% $\mathrm{K}$, the factors $2 \mathrm{mol} \mathrm{P} / \mathrm{mol}$
$\mathrm{P}_{2} \mathrm{O}_{5}$ and $2 \mathrm{mol} \mathrm{K} / \mathrm{mol} \mathrm{K}_{2} \mathrm{O}$ must be used, together
with molar masses.
(a) Assuming three-significant-figure precision, what is the percent composition of the "5-10-5" fertilizer in \% $\mathrm{N}, \% \mathrm{P},$ and $\% \mathrm{K} ?$
(b) What is the $\% \mathrm{P}_{2} \mathrm{O}_{5}$ in the following compounds (both common fertilizers)? (i) $\mathrm{Ca}\left(\mathrm{H}_{2} \mathrm{PO}_{4}\right)_{2}$ (ii) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}$
(c) In a similar manner to the "5-10-5" fertilizer described in this exercise, how would you describe a fertilizer in which the mass ratio of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}$ to KCl is 5.00:1.00?
(d) Can a "5-10-5" fertilizer be prepared in which $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}$ and $\mathrm{KCl}$ are the sole fertilizer components, with or without inert nonfertilizer additives? If so, what should be the proportions of the constituents of the fertilizer mixture? If this "5-10-5" fertilizer cannot be prepared, why not?

Tracy Tourville

Tracy Tourville

Numerade Educator

Problem 112

A hydrate of copper(II) sulfate, when heated, goes through the succession of changes suggested by the photograph. In this photograph, (a) is the original fully hydrated copper(II) sulfate; (b) is the product obtained by heating the original hydrate to $140^{\circ} \mathrm{C}$
(c) is the product obtained by further heating to $400^{\circ} \mathrm{C}$ and (d) is the product obtained at $1000^{\circ} \mathrm{C}$
A $2.574 \mathrm{g}$ sample of $\mathrm{CuSO}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}$ was heated to $140^{\circ} \mathrm{C},$ cooled, and reweighed. The resulting solid was reheated to $400^{\circ} \mathrm{C},$ cooled, and reweighed. Finally, this solid was heated to $1000^{\circ} \mathrm{C},$ cooled, and reweighed for the last time.
$$ \text {Original sample } \quad \quad\quad\quad\quad \text {$2.574 \mathrm{g}$ } $$
$$ \text {After heating to $140^{\circ} \mathrm{C}$ } \quad \quad\quad\quad\quad \text {$1.833 \mathrm{g}$ } $$
$$ \text {After reheating to $400^{\circ} \mathrm{C}$} \quad \quad\quad\quad\quad \text {$1.647 \mathrm{g}$ } $$
$$ \text {After reheating to $1000^{\circ} \mathrm{C}$} \quad \quad\quad\quad\quad \text {$0.812 \mathrm{g}$} $$
(a) Assuming that all the water of hydration is driven off at $400^{\circ} \mathrm{C},$ what is the formula of the original hydrate?
(b) What is the formula of the hydrate obtained when the original hydrate is heated to only $140^{\circ} \mathrm{C} ?$
(c) The black residue obtained at $1000^{\circ} \mathrm{C}$ is an oxide of copper. What is its percent composition and empirical formula?

David Collins

Numerade Educator

Problem 113

Some substances that are only very slightly soluble in water will spread over the surface of water to produce a film that is called a monolayer because it is only one molecule thick. A practical use of this phenomenon is to cover ponds to reduce the loss of water by evaporation. Stearic acid forms a monolayer on water. The molecules are arranged upright and in contact with one another, rather like pencils tightly packed and standing upright in a coffee mug. The model below represents an individual stearic acid molecule in the monolayer.
(a) How many square meters of water surface would be covered by a monolayer made from $10.0 \mathrm{g}$ of stearic acid?
[Hint: What is the formula of stearic acid?]
(b) If stearic acid has a density of $0.85 \mathrm{g} / \mathrm{cm}^{3}$, estimate the length (in nanometers) of a stearic acid molecule. [Hint: What is the thickness of the monolayer described in part a?]
(c) A very dilute solution of oleic acid in liquid pentane is prepared in the following way:
$$\begin{aligned}
&1.00 \mathrm{mL} \text { oleic acid }+9.00 \mathrm{mL} \text { pentane } \rightarrow \text { solution }(1)\\
&1.00 \mathrm{mL} \text { solution }(1)+9.00 \mathrm{mL} \text { pentane } \rightarrow \text { solution }(2)\\
&1.00 \mathrm{mL} \text { solution }(2)+9.00 \mathrm{mL} \text { pentane } \rightarrow \text { solution }(3)\\
&1.00 \mathrm{mL} \text { solution }(3)+9.00 \mathrm{mL} \text { pentane } \rightarrow \text { solution }(4)
\end{aligned}$$
A 0.10 mL sample of solution (4) is spread in a monolayer on water. The area covered by the monolayer is $85 \mathrm{cm}^{2} .$ Assume that oleic acid molecules are arranged in the same way as described for stearic acid, and that the cross-sectional area of the molecule is $4.6 \times 10^{-15} \mathrm{cm}^{2}$. The density of oleic acid is $0.895 \mathrm{g} / \mathrm{mL} .$ Use these data to obtain an approximate value of Avogadro's number.

Niamat Khuda

Numerade Educator

Problem 114

In your own words, define or explain the following terms or symbols: (a) formula unit; (b) $\mathrm{P}_{4} ;$ (c) molecular compound; (d) binary compound; (e) hydrate.

Numerade Educator

Numerade Educator

Numerade Educator

Problem 115

Briefly describe each of the following ideas or methods: (a) mole of a compound; (b) structural formula; (c) oxidation state; (d) carbon-hydrogen-oxygen determination by combustion analysis.

David Collins

Numerade Educator

Problem 116

Explain the important distinctions between each pair of terms: (a) molecular mass and molar mass; (b) empirical and molecular formulas; (c) systematic and trivial, or common, name; (d) hydroxyl and carboxyl functional group.

David Collins

Numerade Educator

Problem 117

Explain each term as it applies to the element nitrogen. (a) atomic mass; (b) molecular mass; (c) molar mass.

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 118

Which answer is correct? One mole of liquid bromine, $\mathrm{Br}_{2},$ (a) has a mass of $79.9 \mathrm{g} ;$ (b) contains $6.022 \times 10^{23}$ Br atoms; (c) contains the same number of atoms as in $12.01 \mathrm{g} \mathrm{H}_{2} \mathrm{O} ;$ (d) has twice the mass of 0.500 mole of gaseous $\mathrm{Cl}_{2}$

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 119

Three of the following formulas might be either an empirical or a molecular formula. The formula that must be a molecular formula is (a) $\mathrm{N}_{2} \mathrm{O} ;$ (b) $\mathrm{N}_{2} \mathrm{H}_{4}$
(c) $\mathrm{NaCl} ;$ (d) $\mathrm{NH}_{3}$

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 120

The compound $\mathrm{C}_{7} \mathrm{H}_{7} \mathrm{NO}_{2}$ contains (a) 17 atoms per mole; (b) equal percents by mass of $\mathrm{C}$ and $\mathrm{H} ;$ (c) about twice the percent by mass of $\mathrm{O}$ as of $\mathrm{N} ;$ (d) about twice the percent by mass of $\mathrm{N}$ as of $\mathrm{H}$.

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 121

The greatest number of $\mathrm{N}$ atoms is found in (a) $50.0 \mathrm{g}$ $\mathrm{N}_{2} \mathrm{O} ;$ (b) $17.0 \mathrm{g} \mathrm{NH}_{3} ;$ (c) $150 \mathrm{mL}$ of liquid pyridine, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}(d=0.983 \mathrm{g} / \mathrm{mL}) ;$ (d) $1.0 \mathrm{mol} \mathrm{N}_{2}$

David Collins

Numerade Educator

Problem 122

$\mathrm{XF}_{3}$ consists of $65 \%$ F by mass. The atomic mass of the element X must be (a) 8 u; (b) 11 u; (c) 31 u; (d) 35 u.

David Collins

Numerade Educator

Problem 123

The oxidation state of I in the ion $\mathrm{H}_{4} \mathrm{IO}_{6}^{-}$ is (a) -1 (b) $+1 ;(c)+7 ;(d)+8$

Katherine Mccandless

Katherine Mccandless

Numerade Educator

Problem 124

The formula for calcium chlorite is (a) $\mathrm{CaClO}_{2}$ (b) $\mathrm{Ca}\left(\mathrm{ClO}_{2}\right)_{2} ;(\mathrm{c}) \mathrm{CaClO}_{3} ;(\mathrm{d}) \mathrm{Ca}\left(\mathrm{ClO}_{4}\right)_{2}$

Natalie Almond

Numerade Educator

Problem 125

A formula unit of the compound $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right] \mathrm{SO}_{4}$ has nearly equal masses of (a) $\mathrm{S}$ and $\mathrm{O} ;$ (b) $\mathrm{N}$ and $\mathrm{O}$ (c) $\mathrm{H}$ and $\mathrm{N} ;$ (d) $\mathrm{Cu}$ and $\mathrm{O}$

David Collins

Numerade Educator

Problem 126

An isomer of the compound $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHOHCH}_{3}$ is
(a) $\mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O} ;$ (b) $\mathrm{CH}_{3} \mathrm{CHOHCH}_{2} \mathrm{CH}_{3}$ (c) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{2} \mathrm{OH} ;$ (d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{3}$

Natalie Almond

Numerade Educator

Problem 127

A hydrate of $\mathrm{Na}_{2} \mathrm{SO}_{3}$ contains almost exactly $50 \% \mathrm{H}_{2} \mathrm{O}$ by mass. What is the formula of this hydrate?

David Collins

Numerade Educator

Problem 128

Malachite is a common copper-containing mineral with the formula $\mathrm{CuCO}_{3} \cdot \mathrm{Cu}(\mathrm{OH})_{2} .$ (a) What is the mass percent copper in malachite? (b) When malachite is strongly heated, carbon dioxide and water are driven off, yielding copper(II) oxide as the sole product. What mass of copper(II) oxide is produced per kg of malachite?

David Collins

Numerade Educator

Problem 129

Acetaminophen, an analgesic and antipyretic drug, has a molecular mass of 151.2 u and a mass percent composition of $63.56 \%$ C $, 6.00 \%$ H, $9.27 \%$ N, and $21.17 \%$ O. What is the molecular formula of acetaminophen?

David Collins

Numerade Educator

Problem 130

Ibuprofen is a compound used in painkillers. When a $2.174 \mathrm{g}$ sample is burned in an excess of oxygen, it yields $6.029 \mathrm{g} \mathrm{CO}_{2}$ and $1.709 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$ as the sole products. (a) What is the percent composition, by mass, of ibuprofen? (b) What is the empirical formula of ibuprofen?

David Collins

Numerade Educator

Problem 131

Appendix E describes a useful study aid known as concept mapping. Using the method presented in Appendix $\mathrm{E},$ construct a concept map illustrating the different concepts in Sections $3-2$ and $3-3$.

David Collins

Numerade Educator