Introductory Chemistry

Problem 10

Write the conversion factors between moles of each constituent element and moles of the compound for $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$

Jorge V.

Numerade Educator

04:46

Problem 11

You can use mass percent composition as a conversion factor between grams of a constituent element and grams of the compound. Write the conversion factor (including units) inherent in each mass percent composition.
(a) Water is $11.19 \%$ hydrogen by mass.
(b) Fructose, also known as fruit sugar, is $53.29 \%$ oxygen by mass.
(c) Octane, a component of gasoline, is $84.12 \%$ carbon by mass.
(d) Ethanol, the alcohol in alcoholic beverages, is $52.14 \%$ carbon by mass.

Jorge V.

Numerade Educator

01:09

Problem 12

What is the mathematical formula for calculating mass percent composition from a chemical formula?

Jorge V.

Numerade Educator

00:47

Problem 13

How are the empirical formula and the molecular formula of a compound related?

Jorge V.

Numerade Educator

01:03

Problem 14

Why is it important to be able to calculate an empirical formula from experimental data?

Jorge V.

Numerade Educator

00:53

Problem 15

What is the empirical formula mass of a compound?

Jorge V.

Numerade Educator

00:51

Problem 16

How are the molar mass and empirical formula mass for a compound related?

Jorge V.

Numerade Educator

01:02

Problem 17

How many mercury atoms are in 5.8 mol of mercury?

Jorge V.

Numerade Educator

01:03

Problem 18

How many moles of gold atoms do $3.45 \times 10^{24}$ gold atoms constitute?

Jorge V.

Numerade Educator

04:27

Problem 19

How many atoms are in each elemental sample?
(a) $3.4 \mathrm{mol} \mathrm{Cu}$
(b) $9.7 \times 10^{-3}$ mol $C$
(c) $22.9 \mathrm{mol} \mathrm{Hg}$
(d) 0.215 mol Na

Jorge V.

Numerade Educator

04:18

Problem 20

How many moles of atoms are in each elemental sample?
(a) $4.6 \times 10^{24} \mathrm{Pb}$ atoms
(b) $2.87 \times 10^{22}$ He atoms
(c) $7.91 \times 10^{23} \mathrm{K}$ atoms
(d) $4.41 \times 10^{21} \mathrm{Ca}$ atoms

Jorge V.

Numerade Educator

04:30

Problem 21

Complete the table.
$$\begin{array}{lll}\hline \text { Element } & \text { Moles } & \text { Number of Atoms } \\\hline \mathrm{Ne} & 0.552 & \\\mathrm{Ar} & & 3.25 \times 10^{24} \\\mathrm{Xe} & 1.78 & \\\mathrm{He} & & 1.08 \times 10^{20} \\\hline\end{array}$$

Jorge V.

Numerade Educator

03:18

Problem 22

Complete the table.
$$\begin{array}{lll}\hline \text { Element } & \text { Moles } & \text { Number of Atoms } \\\hline \mathrm{Cr} & & 9.61 \times 10^{23} \\\mathrm{Fe} & 1.52 \times 10^{-5} & \\\mathrm{Ti} & 0.0365 & \\\mathrm{Hg} & & 1.09 \times10^{23} \\\hline\end{array}$$

Jorge V.

Numerade Educator

01:59

Problem 23

Consider these definitions. $1 \mathrm{doz}=12 \quad 1$ gross $=144$
1 ream $=500 \quad 1 \mathrm{mol}=6.022 \times 10^{23}$
Suppose you have 872 sheets of paper. How many ________ of paper sheets do you have?
(a) dozens
(b) gross
(c) reams
(d) moles

Jorge V.

Numerade Educator

02:40

Problem 24

A pure copper penny contains approximately $3.0 \times 10^{22} \mathrm{cop}-$ per atoms. Use the definitions in the previous problem to determine how many _______ of copper atoms are in a penny.
(a) dozens
(b) gross
(c) reams
(d) moles

Jorge V.

Numerade Educator

01:01

Problem 25

How many moles of tin atoms are in a pure tin cup with a mass of $38.1 \mathrm{g} ?$

Jorge V.

Numerade Educator

00:45

Problem 26

A lead fishing weight contains 0.12 mol of lead atoms. What is its mass?

Jorge V.

Numerade Educator

01:02

Problem 27

A pure gold coin contains 0.145 mol of gold. What is its mass?

Jorge V.

Numerade Educator

00:55

Problem 28

A helium balloon contains $0.46 \mathrm{g}$ of helium. How many moles of helium does it contain?

Jorge V.

Numerade Educator

02:42

Problem 29

How many moles of atoms are in each elemental sample?
(a) $1.34 \mathrm{g} \mathrm{Zn}$
(b) $24.9 \mathrm{g} \mathrm{Ar}$
(c) $72.5 \mathrm{g} \mathrm{Ta}$
(d) $0.0223 \mathrm{g} \mathrm{Li}$

Jorge V.

Numerade Educator

02:43

Problem 30

What is the mass in grams of each elemental sample?
(b) 0.581 mol Ba
(a) $6.64 \mathrm{mol} \mathrm{W}$
(d) 1.57 mol $S$
(c) $68.1 \mathrm{mol} \mathrm{Xe}$

Jorge V.

Numerade Educator

02:37

Problem 31

Complete the table.

Jorge V.

Numerade Educator

03:30

Problem 32

Complete the table.

Jorge V.

Numerade Educator

Problem 33

A pure silver ring contains 0.0134 mmol (millimol) Ag. How many silver atoms does it contain?

Jorge V.

Numerade Educator

Problem 34

A pure gold ring contains 0.0102 mmol (millimol) Au. How many gold atoms does it contain?

Jorge V.

Numerade Educator

Problem 35

How many aluminum atoms are in $3.78 \mathrm{g}$ of aluminum?

Jorge V.

Numerade Educator

Problem 36

What is the mass of $4.91 \times 10^{21}$ platinum atoms?

Eugene S.

University of Minnesota - Twin Cities

03:20

Problem 37

How many atoms are in each elemental sample?
(a) $16.9 \mathrm{g} \mathrm{Sr}$
(b) $26.1 \mathrm{g} \mathrm{Fe}$
(c) $8.55 \mathrm{g} \mathrm{Bi}$
(d) $38.2 \mathrm{g} \mathrm{P}$

Jorge V.

Numerade Educator

04:10

Problem 38

Calculate the mass in grams of each elemental sample.
(a) $1.32 \times 10^{20}$ uranium atoms
(b) $2.55 \times 10^{22}$ zinc atoms
(c) $4.11 \times 10^{23}$ lead atoms
(d) $6.59 \times 10^{24}$ silicon atoms

Jorge V.

Numerade Educator

01:02

Problem 39

How many carbon atoms are in a diamond (pure carbon) with a mass of $38 \mathrm{mg} ?$

Jorge V.

Numerade Educator

01:11

Problem 40

How many helium atoms are in a helium blimp containing $495 \mathrm{kg}$ of helium?

Jorge V.

Numerade Educator

01:08

Problem 41

How many titanium atoms are in a pure titanium bicycle frame with a mass of $1.28 \mathrm{kg} ?$

Jorge V.

Numerade Educator

01:09

Problem 42

How many copper atoms are in a pure copper statue with a mass of 133 kg?

Jorge V.

Numerade Educator

05:43

Problem 43

Complete the table.

Jorge V.

Numerade Educator

06:29

Problem 44

Complete the table.

Jorge V.

Numerade Educator

02:18

Problem 45

Which sample contains the greatest number of atoms?
(a) $27.2 \mathrm{g} \mathrm{Cr}$
(b) $55.1 \mathrm{g} \mathrm{Ti}$
(c) $205 \mathrm{g} \mathrm{Pb}$

Jorge V.

Numerade Educator

02:59

Problem 46

Which sample contains the greatest number of atoms?
(a) $10.0 \mathrm{g} \mathrm{He}$
(b) $25.0 \mathrm{g} \mathrm{Ne}$
(c) $115 \mathrm{g} \mathrm{Xe}$

Jorge V.

Numerade Educator

02:42

Problem 47

Determine the number of moles of molecules (or formula units) in each sample.
(a) $38.2 \mathrm{g}$ sodium chloride
(b) $36.5 \mathrm{g}$ nitrogen monoxide
(c) 4.25 kg carbon dioxide
(d) $2.71 \mathrm{mg}$ carbon tetrachloride

Jorge V.

Numerade Educator

02:44

Problem 48

Determine the mass of each sample.
(a) 1.32 mol carbon tetrafluoride
(b) 0.555 mol magnesium fluoride
(c) 1.29 mmol carbon disulfide
(d) $1.89 \mathrm{kmol}$ sulfur trioxide

Jorge V.

Numerade Educator

06:18

Problem 49

Complete the table.

Jorge V.

Numerade Educator

06:08

Problem 50

Complete the table.

Jorge V.

Numerade Educator

Problem 51

A mothball, composed of naphthalene $\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)$, has a mass of 1.32 g. How many naphthalene molecules does it contain?

Jorge V.

Numerade Educator

00:30

Problem 52

Calculate the mass in grams of a single water molecule.

Jorge V.

Numerade Educator

03:31

Problem 53

How many molecules are in each sample?
(a) $3.5 \mathrm{g} \mathrm{H}_{2} \mathrm{O}$
(b) $56.1 \mathrm{g} \mathrm{N}_{2}$
(c) $89 \mathrm{g} \mathrm{CCl}_{4}$
(d) $19 \mathrm{g} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$

Jorge V.

Numerade Educator

03:39

Problem 54

Calculate the mass in grams of each sample.
(a) $5.94 \times 10^{20} \mathrm{H}_{2} \mathrm{O}_{2}$ molecules
(b) $2.8 \times 10^{22} \mathrm{SO}_{2}$ molecules
(c) $4.5 \times 10^{25} \mathrm{O}_{3}$ molecules
(d) $9.85 \times 10^{19}$
$\mathrm{CH}_{4}$ molecules

Jorge V.

Numerade Educator

01:18

Problem 55

A sugar crystal contains approximately $1.8 \times 10^{17}$ sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ molecules. What is its mass in milligrams?

Jorge V.

Numerade Educator

04:57

Problem 56

A salt crystal has a mass of $0.12 \mathrm{mg}$. How many $\mathrm{NaCl}$ formula units does it contain?

Jessica L.

Florida International University

02:05

Problem 57

How much money, in dollars, does one mole of pennies represent? If this amount of money were evenly distributed to the entire world's population (about 7.1 billion people), how much would each person get? Would each person be a millionaire? Billionaire? Trillionaire?

Jorge V.

Numerade Educator

01:59

Problem 58

A typical dust particle has a diameter of about $10.0 \mu \mathrm{m}$. If 1.0 mol of dust particles were laid end to end along the equator, how many times would they encircle the planet? The circumference of the Earth at the equator is $40,076 \mathrm{km}$

Jorge V.

Numerade Educator

00:45

Problem 59

Determine the number of moles of $\mathrm{Cl}$ in $2.7 \mathrm{mol} \mathrm{CaCl}_{2}$

Jorge V.

Numerade Educator

00:51

Problem 60

$$\text { How many moles of O are in } 12.4 \mathrm{mol} \mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3} ?$$

Jorge V.

Numerade Educator

01:49

Problem 61

Which sample contains the greatest number of moles of O?
(a) $2.3 \mathrm{mol} \mathrm{H}_{2} \mathrm{O}$
(b) $1.2 \mathrm{mol} \mathrm{H}_{2} \mathrm{O}_{2}$
(c) $0.9 \mathrm{mol} \mathrm{NaNO}_{3}$
(d) $0.5 \mathrm{mol} \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$

Jorge V.

Numerade Educator

02:26

Problem 62

Which sample contains the greatest number of moles of $\mathrm{Cl}$ ?
(a) 3.8 mol HCl
(b) $1.7 \mathrm{mol} \mathrm{CH}_{2} \mathrm{Cl}_{2}$
(c) $4.2 \mathrm{mol} \mathrm{NaClO}_{3}$
(d) $2.2 \mathrm{mol} \mathrm{Mg}\left(\mathrm{ClO}_{4}\right)_{2}$

Jorge V.

Numerade Educator

03:21

Problem 63

Determine the number of moles of $\mathrm{C}$ in each sample.
(a) $2.5 \mathrm{mol} \mathrm{CH}_{4}$
(b) $0.115 \mathrm{mol} \mathrm{C}_{2} \mathrm{H}_{6}$
(c) $5.67 \mathrm{mol} \mathrm{C}_{4} \mathrm{H}_{10}$
(d) $25.1 \mathrm{mol} \mathrm{C}_{8} \mathrm{H}_{18}$

Jennifer H.

Numerade Educator

01:45

Problem 64

Determine the number of moles of $\mathrm{H}$ in each sample.
(a) $4.67 \mathrm{mol} \mathrm{H}_{2} \mathrm{O}$
(b) $8.39 \mathrm{mol} \mathrm{NH}_{3}$
(c) $0.117 \mathrm{mol} \mathrm{N}_{2} \mathrm{H}_{4}$
(d) $35.8 \mathrm{mol} \mathrm{C}_{10} \mathrm{H}_{22}$

Jorge V.

Numerade Educator

04:28

Problem 65

For each set of molecular models, write a relationship between moles of hydrogen and moles of molecules. Then determine the total number of hydrogen atoms present. $(\mathrm{H}-\text { white; } \mathrm{O}-\text { red } ; \mathrm{C}-\text { black; } \mathrm{N}-\text { blue })$

Jorge V.

Numerade Educator

03:08

Problem 66

For each set of molecular models, write a relationship between moles of oxygen and moles of molecules. Then determine the total number of oxygen atoms present. (H? white; O-red; C-black; S-yellow)

Jorge V.

Numerade Educator

04:39

Problem 67

How many grams of $\mathrm{Cl}$ are in $38.0 \mathrm{g}$ of each sample of chlorofluorocarbons (CFCs)?
(a) $\mathrm{CF}_{2} \mathrm{Cl}_{2}$
(b) $\mathrm{CFCl}_{3}$
(c) $\mathrm{C}_{2} \mathrm{F}_{3} \mathrm{Cl}_{3}$
(d) $\mathrm{CF}_{3} \mathrm{Cl}$

Jorge V.

Numerade Educator

04:11

Problem 68

Calculate the number of grams of sodium in $1.00 \mathrm{g}$ of each sodium-containing food additive.
(a) NaCl (table salt)
(b) $\mathrm{Na}_{3} \mathrm{PO}_{4}$ (sodium phosphate)
(c) $\mathrm{NaC}_{7} \mathrm{H}_{5} \mathrm{O}_{2}$ (sodium benzoate)
(d) $\mathrm{Na}_{2} \mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{7}$ (sodium hydrogen citrate)

Jorge V.

Numerade Educator

02:43

Problem 69

Iron is found in Earth's crust as several different iron compounds. Calculate the mass (in $\mathrm{kg}$ ) of each compound that contains $1.0 \times 10^{3} \mathrm{kg}$ of iron.
(a) $\mathrm{Fe}_{2} \mathrm{O}_{3}$ (hematite)
(b) $\mathrm{Fe}_{3} \mathrm{O}_{4}$ (magnetite)
(c) $\mathrm{FeCO}_{3}$ (siderite)

Jorge V.

Numerade Educator

02:41

Problem 70

Lead is found in Earth's crust as several lead compounds. Calculate the mass (in $\mathrm{kg}$ ) of each compound that contains $1.0 \times 10^{3} \mathrm{kg}$ of lead.
(a) PbS (galena)
(b) $\overline{\mathrm{PbCO}}_{3}$ (cerussite)
(c) $\quad \mathrm{PbSO}_{4}$ (anglesite)

Jorge V.

Numerade Educator

00:47

Problem 71

A $2.45-\mathrm{g}$ sample of strontium completely reacts with oxygen to form $2.89 \mathrm{g}$ of strontium oxide. Use this data to calculate the mass percent composition of strontium in strontium oxide.

Jorge V.

Numerade Educator

Problem 72

A 4.78-g sample of aluminum completely reacts with oxygen to form $6.67 \mathrm{g}$ of aluminum oxide. Use this data to calculate the mass percent composition of aluminum in aluminum oxide.

Jorge V.

Numerade Educator

01:18

Problem 73

A 1.912 -g sample of calcium chloride is decomposed into its constituent elements and found to contain $0.690 \mathrm{g} \mathrm{Ca}$ and 1.222 $\mathrm{g}$ Cl. Calculate the mass percent composition of $\mathrm{Ca}$ and Cl in calcium chloride.

Jorge V.

Numerade Educator

01:33

Problem 74

A $0.45-g$ sample of aspirin is decomposed into its constituent elements and found to contain $0.27 \mathrm{g} \mathrm{C}, 0.020 \mathrm{g} \mathrm{H},$ and $0.16 \mathrm{g}$ O. Calculate the mass percent composition of $\mathrm{C}, \mathrm{H}$ and O in aspirin.

Jorge V.

Numerade Educator

Problem 75

Copper(II) fluoride contains $37.42 \%$ F by mass. Use this percentage to calculate the mass of fluorine in grams contained in $28.5 \mathrm{g}$ of copper(II) fluoride.

Jorge V.

Numerade Educator

00:57

Problem 76

Silver chloride, used in silver plating, contains $75.27 \%$ Ag. Calculate the mass of silver chloride in grams required to make $4.8 \mathrm{g}$ of silver plating.

Jorge V.

Numerade Educator

01:12

Problem 77

In small amounts, the fluoride ion (often consumed as $\mathrm{NaF}$ ) prevents tooth decay. According to the American Dental Association, an adult female should consume $3.0 \mathrm{mg}$ of fluorine per day. Calculate the amount of sodium fluoride $(45.24 \% \mathrm{F})$ that a woman should consume to get the recommended amount of fluorine.

Jorge V.

Numerade Educator

Problem 78

The iodide ion, usually consumed as potassium iodide, is a dietary mineral essential to good nutrition. In countries where potassium iodide is added to salt, iodine deficiency or goiter has been almost completely eliminated. The recommended daily allowance (RDA) for iodine is $150 \mu \mathrm{g} /$ day. How much potassium iodide (76.45\% I) should you consume to meet the RDA?

Jorge V.

Numerade Educator

02:41

Problem 79

Calculate the mass percent composition of nitrogen in each compound.
(a) $\mathrm{N}_{2} \mathrm{O}$
(b) NO
(c) $\mathrm{NO}_{2}$
(d) $\mathrm{N}_{2} \mathrm{O}_{5}$

Jorge V.

Numerade Educator

02:30

Problem 80

Calculate the mass percent composition of carbon in each compound.
(a) $\mathrm{C}_{2} \mathrm{H}_{2}$
(b) $\mathrm{C}_{3} \mathrm{H}_{6}$
(c) $\mathrm{C}_{2} \mathrm{H}_{6}$
(d) $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$

Jorge V.

Numerade Educator

05:36

Problem 81

Calculate the mass percent composition of each element in each compound.
(a) $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}_{2}$
(b) $\mathrm{CH}_{2} \mathrm{O}_{2}$
(c) $\mathrm{C}_{3} \mathrm{H}_{9} \mathrm{N}$
(d) $\mathrm{C}_{4} \mathrm{H}_{12} \mathrm{N}_{2}$

Jorge V.

Numerade Educator

05:40

Problem 82

Calculate the mass percent composition of each element in each compound.
(a) $\mathrm{FeCl}_{3}$
(b) $\mathrm{TiO}_{2}$
(c) $\mathrm{H}_{3} \mathrm{PO}_{4}$
(d) $\mathrm{HNO}_{3}$

Jorge V.

Numerade Educator

02:21

Problem 83

Calculate the mass percent composition of $\mathrm{O}$ in each compound.
(a) calcium nitrate
(b) iron(II) sulfate
(c) carbon dioxide

Jorge V.

Numerade Educator

01:51

Problem 84

Calculate the mass percent composition of $\mathrm{Cl}$ in each compound.
(a) carbon tetrachloride
(b) calcium hypochlorite
(c) perchloric acid

Jorge V.

Numerade Educator

02:16

Problem 85

Various iron ores have different amounts of iron per kilogram of ore. Calculate the mass percent composition of iron for each iron ore: $\mathrm{Fe}_{2} \mathrm{O}_{3}$ (hematite), $\mathrm{Fe}_{3} \mathrm{O}_{4}$ (magnetite), $\mathrm{FeCO}_{3}$ (siderite). Which ore has the highest iron content?

Jorge V.

Numerade Educator

02:21

Problem 86

Plants need nitrogen to grow, so many fertilizers consist of nitrogen-containing compounds. Calculate the mass percent composition of nitrogen in each fertilizer: $\mathrm{NH}_{3}, \mathrm{CO}\left(\mathrm{NH}_{2}\right)_{2}, \mathrm{NH}_{4} \mathrm{NO}_{3},\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} .$ Which fertilizer has
the highest nitrogen content?

Jorge V.

Numerade Educator

01:18

Problem 87

A compound containing nitrogen and oxygen is decomposed in the laboratory and produces $1.78 \mathrm{g}$ of nitrogen and $4.05 \mathrm{g}$ of oxygen. Calculate the empirical formula of the compound.

Jorge V.

Numerade Educator

01:46

Problem 88

A compound containing selenium and fluorine is decomposed in the laboratory and produces $2.231 \mathrm{g}$ of selenium and $3.221 \mathrm{g}$ of fluorine. Calculate the empirical formula of the compound.

Jorge V.

Numerade Educator

06:40

Problem 89

Samples of several compounds are decomposed, and the masses of their constituent elements are measured. Calculate the empirical formula for each compound.
(a) $1.245 \mathrm{g} \mathrm{Ni}, 5.381 \mathrm{g} \mathrm{I}$
(b) $1.443 \mathrm{g} \mathrm{Se}, 5.841 \mathrm{g} \mathrm{Br}$
(c) $2.128 \mathrm{g}$ Be, $7.557 \mathrm{g} \mathrm{S}, 15.107 \mathrm{g} \mathrm{O}$

Jorge V.

Numerade Educator

06:06

Problem 90

Jorge V.

Numerade Educator

02:22

Problem 91

The rotten smell of a decaying animal carcass is partially due to a nitrogen-containing compound called putrescine. Elemental analysis of putrescine indicates that it consists of $54.50 \%$ C. $13.73 \%$ H, and $31.77 \%$ N. Calculate the empirical formula of putrescine.

Jorge V.

Numerade Educator

02:56

Problem 92

Citric acid, the compound responsible for the sour taste of lemons, has the elemental composition: $\mathrm{C}, 37.51 \% ; \mathrm{H}$ $4.20 \% ; \mathrm{O}, 58.29 \% .$ Calculate the empirical formula of citric acid.

Jorge V.

Numerade Educator

08:17

Problem 93

These compounds are found in many natural flavors and scents. Calculate the empirical formula for each compound.
(a) ethyl butyrate (pineapple oil): $C, 62.04 \% ; \mathrm{H}, 10.41 \% ; \mathrm{O}$
$27.55 \%$
(b) methyl butyrate (apple flavor): $\mathrm{C}, 58.80 \% ; \mathrm{H}, 9.87 \% ; \mathrm{O}$ $31.33 \%$
(c) benzyl acetate (oil of jasmine): $\mathrm{C}, 71.98 \% ; \mathrm{H}, 6.71 \% ; \mathrm{O}$ $21.31 \%$

Jorge V.

Numerade Educator

05:08

Problem 94

Calculate the empirical formula for each over-the-counter pain reliever $\mathrm{N}$
(a) acetaminophen (Tylenol): $\mathrm{C}, 63.56 \% ; \mathrm{H}, 6.00 \%$ $9.27 \% ; \mathrm{O}, 21.17 \%$
(b) naproxen (Aleve): $\mathrm{C}, 73.03 \% ; \mathrm{H}, 6.13 \% ; \mathrm{O}, 20.84 \%$

Jorge V.

Numerade Educator

Problem 95

A $1.45-g$ sample of phosphorus burns in air and forms $2.57 \mathrm{g}$ of a phosphorus oxide. Calculate the empirical formula of the oxide.

Jorge V.

Numerade Educator

01:33

Problem 96

A $2.241-g$ sample of nickel reacts with oxygen to form $2.852 \mathrm{g}$ of the metal oxide. Calculate the empirical formula of the oxide.

Jorge V.

Numerade Educator

02:04

Problem 97

A $0.77-\mathrm{mg}$ sample of nitrogen reacts with chlorine to form 6.61 mg of the chloride. What is the empirical formula of the nitrogen chloride?

Jorge V.

Numerade Educator

01:36

Problem 98

A 45.2 -mg sample of phosphorus reacts with selenium to form $131.6 \mathrm{mg}$ of the selenide. What is the empirical formula of the phosphorus selenide?

Jorge V.

Numerade Educator

01:14

Problem 99

A compound containing carbon and hydrogen has a molar mass of $56.11 \mathrm{g} / \mathrm{mol}$ and an empirical formula of $\mathrm{CH}_{2}$ Determine its molecular formula.

Jorge V.

Numerade Educator

00:42

Problem 100

A compound containing phosphorus and oxygen has a molar mass of $219.9 \mathrm{g} / \mathrm{mol}$ and an empirical formula of $\mathrm{P}_{2} \mathrm{O}_{3} .$ Determine its molecular formula.

Jorge V.

Numerade Educator

02:17

Problem 101

The molar masses and empirical formulas of several compounds containing carbon and chlorine are listed here. Find the molecular formula of each compound.
(a) $284.77 \mathrm{g} / \mathrm{mol}, \mathrm{CCl}$
(b) $131.39 \mathrm{g} / \mathrm{mol}, \mathrm{C}_{2} \mathrm{HCl}_{3}$
(c) $181.44 \mathrm{g} / \mathrm{mol}, \mathrm{C}_{2} \mathrm{HCl}$

Jorge V.

Numerade Educator

02:13

Problem 102

The molar masses and empirical formulas of several compounds containing carbon and nitrogen are listed here. Find the molecular formula of each compound.
(a) $163.26 \mathrm{g} / \mathrm{mol}, \mathrm{C}_{11} \mathrm{H}_{17} \mathrm{N}$
(b) $186.24 \mathrm{g} / \mathrm{mol}, \mathrm{C}_{6} \mathrm{H}_{7} \mathrm{N}$
(c) $312.29 \mathrm{g} / \mathrm{mol}, \mathrm{C}_{3} \mathrm{H}_{2} \mathrm{N}$

Jorge V.

Numerade Educator

01:43

Problem 103

A pure copper cube has an edge length of $1.42 \mathrm{cm} .$ How many copper atoms does it contain? (volume of a cube $=$ (edge length) $^{3}$; density of copper $=8.96 \mathrm{g} / \mathrm{cm}^{3}$ )

Jorge V.

Numerade Educator

01:36

Problem 104

A pure silver sphere has a radius of $0.886 \mathrm{cm} .$ How many silver atoms does it contain? (volume of a sphere $=\frac{4}{3} \pi \mathrm{r}^{3}$ density of silver $=10.5 \mathrm{g} / \mathrm{cm}^{3}$ )

Jorge V.

Numerade Educator

02:48

Problem 105

A drop of water has a volume of approximately $0.05 \mathrm{mL}$ How many water molecules does it contain? (density of water $=1.0 \mathrm{g} / \mathrm{cm}^{3}$ )

James I.

Numerade Educator

02:22

Problem 106

Fingernail-polish remover is primarily acetone $\left(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}\right)$ How many acetone molecules are in a bottle of acetone with a volume of $325 \mathrm{mL}$ ? (density of acetone $=0.788 \mathrm{g} / \mathrm{cm}^{3}$ )

Jorge V.

Numerade Educator

05:31

Problem 107

Complete the table.

Jorge V.

Numerade Educator

05:28

Problem 108

Complete the table.

Jorge V.

Numerade Educator

05:12

Problem 109

Determine the chemical formula of each compound and refer to the formula to calculate the mass percent composition of each constituent element.
(a) copper(II) iodide
(b) sodium nitrate
(c) lead(II) sulfate
(d) calcium fluoride

Jorge V.

Numerade Educator

04:16

Problem 110

Determine the chemical formula of each compound and refer to the formula to calculate the mass percent composition of each constituent element.
(a) nitrogen triiodide
(b) xenon tetrafluoride
(c) phosphorus trichloride
(d) carbon monoxide

Jorge V.

Numerade Educator

01:15

Problem 111

The rock in a particular iron ore deposit contains $78 \%$ $\mathrm{Fe}_{2} \mathrm{O}_{3}$ by mass. How many kilograms of the rock must a mining company process to obtain $1.0 \times 10^{3} \mathrm{kg}$ of iron?

Jorge V.

Numerade Educator

Problem 112

The rock in a lead ore deposit contains $84 \%$ PbS by mass. How many kilograms of the rock must a mining company process to obtain $1.0 \mathrm{kg}$ of $\mathrm{Pb}$ ?

Jorge V.

Numerade Educator

Problem 113

A leak in the air conditioning system of an office building releases $12 \mathrm{kg}$ of $\mathrm{CHF}_{2} \mathrm{Cl}$ per month. If the leak continues, how many kilograms of Clare emitted into the atmosphere each year?

Jorge V.

Numerade Educator

01:35

Problem 114

A leak in the air conditioning system of an older car releases $55 \mathrm{g}$ of $\mathrm{CF}_{2} \mathrm{Cl}_{2}$ per month. How much $\mathrm{Cl}$ is emitted into the atmosphere each year by this car?

Jorge V.

Numerade Educator

01:28

Problem 115

Hydrogen is a possible future fuel. However, elemental hydrogen is rare, so it must be obtained from a hydrogencontaining compound such as water. If hydrogen were obtained from water, how much hydrogen, in grams, could be obtained from $1.0 \mathrm{L}$ of water? (density of water $=1.0 \mathrm{g} / \mathrm{cm}^{3}$ )

Jorge V.

Numerade Educator

01:08

Problem 116

Hydrogen, a possible future fuel mentioned in Problem 115, can also be obtained from ethanol. Ethanol can be made from the fermentation of crops such as corn. How much hydrogen, in grams, could be obtained from $1.0 \mathrm{kg}$ of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right) ?$

Jorge V.

Numerade Educator

07:03

Problem 117

Complete the table of compounds that contain only carbon and hydrogen.

Jorge V.

Numerade Educator

05:33

Problem 118

Complete the table of compounds that contain only carbon and hydrogen.

Jorge V.

Numerade Educator

01:46

Problem 119

Butanedione, a component of butter and body odor, has a cheesy smell. Elemental analysis of butanedione gave the mass percent composition: $\mathrm{C}, 55.80 \% ; \mathrm{H}, 7.03 \% ; \mathrm{O}$ 37.17\%. The molar mass of butanedione is $86.09 \mathrm{g} / \mathrm{mol}$ Determine the molecular formula of butanedione.

Jorge V.

Numerade Educator

03:17

Problem 120

Caffeine, a stimulant found in coffee and soda, has the mass percent composition: $\mathrm{C}, 49.48 \% ; \mathrm{H}, 5.19 \% ; \mathrm{N}$ $28.85 \% ; \mathrm{O}, 16.48 \% .$ The molar mass of caffeine is 194.19 $\mathrm{g} / \mathrm{mol} .$ Find the molecular formula of caffeine.

Jorge V.

Numerade Educator

02:13

Problem 121

Nicotine, a stimulant found in tobacco, has the mass percent composition: $\mathrm{C}, 74.03 \% ; \mathrm{H}, 8.70 \% ; \mathrm{N}, 17.27 \% .$ The molar mass of nicotine is $162.26 \mathrm{g} / \mathrm{mol}$. Find the molecular formula of nicotine.

Jorge V.

Numerade Educator

01:59

Problem 122

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

Jorge V.

Numerade Educator

Problem 123

A sample contains both KBr and KI in unknown quantities. If the sample has a total mass of $5.00 \mathrm{g}$ and contains 1.51 g K, what are the percentages of KBr and KI in the sample by mass?

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Problem 124

A sample contains both $\mathrm{CO}_{2}$ and Ne in unknown quantities. If the sample contains a combined total of $1.75 \mathrm{mol}$ and has a total mass of $65.3 \mathrm{g}$, what are the percentages of $\mathrm{CO}_{2}$ and $\mathrm{Ne}$ in the sample by mole?

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Problem 125

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Problem 126

Methanethiol (CH_S) has a disagreeable odor and is often a component of bad breath. When methanethiol is burned, the sulfur reacts with oxygen to form $\mathrm{SO}_{2}$. What mass of $\mathrm{SO}_{2}$ forms upon the complete combustion of $1.89 \mathrm{g}$ of methanethiol?

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01:30

Problem 127

An iron ore contains $38 \% \mathrm{Fe}_{2} \mathrm{O}_{3}$ by mass. What is the maximum mass of iron that can be recovered from 10.0 kg of this ore?

Jorge V.

Numerade Educator

02:56

Problem 128

Seawater contains approximately $3.5 \%$ NaCl by mass and has a density of $1.02 \mathrm{g} / \mathrm{mL}$. What volume of seawater contains $1.0 \mathrm{g}$ of sodium?

Jorge V.

Numerade Educator