Deck 3: Stoichiometry: Mass, Formulas, and Reactions

Question 1

A particular manufacturer sells phosphoric acid capsules as a homeopathic remedy with a concentration specified as 23X. (23X means that when averaged over many capsules, the average mass of phosphoric acid in one capsule is 10^-23 times the mass of the capsule. The rest is a carbohydrate filler.) If each capsule has a mass of 35 mg, approximately how many capsules would you have to take to expect to ingest at least one molecule of H₃PO₄ (98.0 g/mol)?

A)1
B)5
C)50
D)500
E)5000

Answer 1

500

Question 2

In one analysis, 3.01 10¹³ molecules of ozone were found in 1.00 mL of an air sample. How many moles of ozone is this?

A)5.00 10^-11 mol
B)1.81 10³⁷ mol
C)1.81 10^-11 mol
D)5.00 10³⁷ mol
E)6.02 10^-23 mol

Answer 2

5.00 10^-11 mol

Question 3

Which one of the following samples contains the largest number of molecules?

A)55 g of H₂O
B)3 moles of H₂O
C)3 moles of HF
D)62 g of H₂O
E)62 g of HF

Answer 3

62 g of H₂O

Question 4

How many hydrogen atoms are there in a 346 g sample of pure ammonia (NH₃)?

A)3.67 10²⁵ atoms
B)1.22 10²⁵ atoms
C)60.9 atoms
D)20.3 atoms
E)4.89 10²⁵ atoms

Question 5

One mole is defined as ________

A)the number of particles equal to the number of atoms in exactly 12 g of carbon-12.
B)the number of particles equal to the number of atoms in exactly 16 g of oxygen-16.
C)exactly 6.02 10²² particles.
D)the number of particles equal to the number of atoms in exactly 1 g of hydrogen-1.
E)the number of particles equal to the number of atoms in exactly 1 kg of carbon in a vault at the National Bureau of Standards.

Question 6

A gallon of water has a mass of 3.79 kg. How many moles of water (18.02 g/mol) is this?

A)0.210 mol
B)210 mol
C)68.3 mol
D)68,300 mol
E)386 mol

Question 7

How many moles of ammonia are there in a 346 g sample of pure NH₃ (17.03 g/mol)?

A)0.0496 mol
B)20.3 mol
C)24.7 mol
D)5,930 mol
E)3.46 mol

Question 8

Which statement about the following chemical reaction is not correct? 2H₂

O₂

2H₂

O₂

A)For every oxygen molecule consumed, two water molecules are produced.
B)For every two hydrogen molecules consumed, two water molecules are produced.
C)Two hydrogen molecules react with one oxygen molecule.
D)Four hydrogen molecules react with oxygen to produce two water molecules.
E)Four hydrogen atoms combine with two oxygen atoms to produce two water molecules.

Question 9

In one analysis, the density of ozone in an air sample was found to be 5.00 10^-8 mol/L. What is the density in molecules per liter?

A)8.30 10^-32
B)3.01 10¹⁶
C)1.81 10^-11
D)3.01 10¹¹
E)6.02 10²³

Question 10

For a standard airbag, 131 g of sodium azide (65.00 g/mol) is required to generate enough gas to adequately fill the airbag. How many formula units of sodium azide are needed?

A)3.35 10^-24 formula units
B)1.21 10²⁴ formula units
C)7.89 10²⁵ formula units
D)1.41 10^-20 formula units
E)5.13 10²⁷ formula units

Question 11

A sample of water (H₂O) contains 1.81 10²⁴ molecules. How many total moles of atoms are there in this sample?

A)1.00
B)2.00
C)3.00
D)6.00
E)9.00

Question 12

Which of the following contains the largest number of atoms?

A)1 mol water
B)1 mol phosphorus trichloride
C)1 mol dinitrogen pentoxide
D)1 mol carbon dioxide
E)All of these contain the same number of atoms.

Question 13

How many chlorine atoms are there in 16.0 g of carbon tetrachloride (CCl₄)?

A)6.91 10²⁵
B)1.04 10^-1
C)6.26 10²²
D)2.51 10²³
E)4.23 10¹⁷

Question 14

Which statement about the combustion of propane (C₃H₈) is not correct? C₃H₈

5O₂

3CO₂

4H₂O

A)For every propane molecule consumed, three molecules of carbon dioxide are produced.
B)For every two molecules of propane consumed, eight molecules of water are produced.
C)For every five molecules of oxygen consumed, four molecules of water are produced.
D)For every three molecules of carbon dioxide produced, five molecules of oxygen are consumed.
E)For every carbon dioxide molecule produced, four molecules of water are also produced.

Question 15

How many atoms of chlorine are there in 25.0 g of calcium chloride (CaCl₂)?

A)1.36 10²³ atoms
B)2.67 10²⁴ atoms
C)2.71 10²³ atoms
D)1.95 10²³ atoms

Question 16

Which statement A-D regarding the terms mole and molar mass is not correct?

A)A mole is defined as the number of particles in exactly 12 g of carbon-12.
B)A mole of oxygen gas contains 6.022 10²³ molecules.
C)Two moles of oxygen atoms can be obtained by decomposing one mole of carbon dioxide.
D)To obtain the molar mass in grams (g/mol) from the atomic mass in atomic mass units(u), multiply by 6.022 10²³/mol and divide by 6.022 10²³ u/g.
E)Statements A-D all are correct.

Question 17

Which substance listed below contains the most oxygen atoms?

A)1 mol of Al₂O₃
B)1 mol of Fe₂O₃
C)2 mol of N₂O₄
D)2 mol of CO₂
E)2 mol of HNO₃

Question 18

In one analysis, 1.34 10¹⁷ molecules of ozone (O₃) were found in 2.00 mL of an air sample. How many moles of oxygen atoms is this?

A)2.23 10^-7 mol
B)8.07 10⁴⁰ mol
C)6.68 10^-7 mol
D)2.42 10⁴¹ mol
E)6.02 10^-23 mol

Question 19

How many gold atoms are there in a 1.00 kg bar of gold?

A)3.06 10²⁴
B)197 mol
C)3.06 10²¹
D)5.08 10^-3 mol
E)5.08 10¹⁸

Question 20

A tiny speck (8.3 10^-7 mol) of radioactive americium-241 is used in smoke detectors. How many atoms of americium-241 are there in one of these smoke detectors?

A)5.0 10¹⁷
B)1.2 10²⁰
C)2.9 10²²
D)6.0 10²³
E)8.3 10⁷

Question 21

How many mL of hexadecane (C₁₆H₃₄) are needed to react with 0.050 mol O₂, assuming complete combustion occurs? The density of C₁₆H₃₄ is 0.80 g/mL.

A)0.99 mL
B)0.37 mL
C)0.58 mL
D)0.46 mL
E)0.89 mL

Question 22

Which statement about the following chemical reaction is not correct? 2NH₃ + 2O₂ $\to$ N₂O + 3H₂O

A)It requires 2 mol of dioxygen to produce 1 mol of N₂O.
B)It requires 2 mol of ammonia to produce 3 mol of water.
C)Two moles of ammonia react with two moles of dioxygen.
D)Two moles of N₂O would be produced when four moles of dioxygen are consumed.
E)Nine moles of water are produced when four moles of ammonia are consumed.

Question 23

Hydrogen peroxide decomposes to produce water and oxygen. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2H₂O₂ $\to$ 2H₂O + O₂

A)2 molecules 2 molecules +1 molecules
B)34.0 g 18.0 g 16.0 g
C)68.0 g 36.0 g 32.0 g
D)2x mol 2x mol x mol
E)y(34.0 g) y(18.0 g) y(32 g)

Question 24

Fuming sulfuric acid is obtained by the addition of SO₃ to concentrated H₂SO₄. The fumes result from the reaction of SO₃ gas with water vapor. What is the product when one molecule of SO₃ reacts with one molecule of water?

A)two molecules of sulfurous acid
B)one sulfate ion
C)two sulfite ions
D)one molecule of sulfuric acid
E)two molecules of sulfuric acid

Question 25

Air bags in cars inflate when an electrical spark activates sodium azide (NaN₃) so that it decomposes to sodium metal, Na, and nitrogen gas, N₂. In the balanced reaction equation, how many moles of nitrogen gas are formed for each mole of sodium azide?

A)1
B)1.5
C)2
D)3
E)2.5

Question 26

Sulfur dioxide from coal-fired power plants combines with water in the atmosphere to produce acid rain. What is the product when one molecule of SO₂ reacts with one molecule of water?

A)two molecules of sulfurous acid
B)one sulfate ion
C)two sulfite ions
D)one molecule of sulfuric acid
E)one molecule of sulfurous acid

Question 27

Fe₂O₃(s) and powdered aluminum can react with great output of heat to form molten iron and Al₂O₃. When this reaction equation is balanced, what are the stoichiometric coefficients in the following order: Fe₂O₃, Al, Fe, Al₂O₃?

A)1, 1, 1, 1
B)2, 2, 2, 2
C)1, 2, 2, 1
D)2, 1, 1, 2
E)1, 1, 2, 2

Question 28

Nitrogen monoxide undergoes combustion to produce nitrogen dioxide. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2NO O₂ 2NO₂

A)2x g x g 2x g
B)2 molecules +1 molecule 2 molecules
C)60.0 g 32.0 g 92.0 g
D)(2y)(30.0 g) y (32.0 g) (2y)(46.0 g)
E)15.0 g 8.0 g 23.0 g

Question 29

How many nitrogen atoms are there in 51.0 g of (NH₄)₂SO₄ (ammonium sulfate)?

A)2.32 10²³ atoms
B)3.07 10²⁵ atoms
C)4.65 10²³ atoms
D)6.14 10²⁵ atoms
E)5.39 10²³ atoms

Question 30

What is the molar mass of sulfuric acid (H₂SO₄)?

A)49.0 g/mol
B)24.5 g/mol
C)101 g/mol
D)98.1 g/mol
E)97.0 g/mol

Question 31

Which of the following cartoons depict a balanced reaction?

A)
B)
C)
D)
E)

Question 32

The acid-base reaction between phosphoric acid, H₃PO₄, and calcium hydroxide, Ca(OH)₂, yields water and calcium phosphate. For each mole of calcium phosphate produced by this reaction, how many moles of water are produced?

A)1
B)2
C)3
D)4
E)6

Question 33

Which statement about the following chemical reaction is not correct? 3H₂
N₂

2NH₃

A)For every mole of nitrogen consumed, two moles of ammonia are produced.
B)For every two moles of nitrogen consumed, three moles of ammonia are produced.
C)For every three moles of hydrogen consumed, two moles of ammonia are produced.
D)For every two moles of ammonia produced, three moles of hydrogen are consumed.
E)Three moles of hydrogen will react with one mole of nitrogen to produce ammonia.

Question 34

As a purchasing agent for a pharmaceutical company, how much chlorine, Cl₂, do you need to order to react completely with 500 kg of platinum, Pt, to make cisplatin, PtCl₂(NH₃)₂?

A)182 kg
B)500 kg
C)2,564 kg
D)364 kg
E)91 kg

Question 35

Which statement about a balanced chemical reaction equation is always correct?

A)The total number of moles of the products equals the total number of moles of the reactants.
B)The number of atoms of each kind is the same for the products as for the reactants.
C)The sum of the stoichiometric coefficients for the products equals the sum of the stoichiometric coefficients for the reactants.
D)The sum of the masses of gaseous reactants equals the sum of the masses of gaseous products.
E)The sum of the masses of solid products equals the sum of the masses of solid reactants.

Question 36

What is the molar mass of phosphorus pentachloride (PCl₅)?

A)177.25 g/mol
B)190.30 g/mol
C)208.22 g/mol
D)172.75 g/mol
E)202.82 g/mol

Question 37

What is the formula mass of (NH₄)₃PO₄ (ammonium phosphate)?

A)62.0 g/mol
B)113 g/mol
C)131 g/mol
D)149 g/mol
E)303 g/mol

Question 38

Which of the following cartoons depict a balanced reaction?

A)
B)
C)
D)
E)

Question 39

How many oxygen atoms are there in 27.0 g of sodium sulfate (Na₂SO₄)?

A)1.15 10²³ atoms
B)4.58 10²³ atoms
C)5.73 10²³ atoms
D)2.41 10²⁴ atoms
E)6.88 10²³ atoms

Question 40

Identify the list below that has these chloride compounds arranged in order of increasing molar mass.

A)CCl₄ PCl₃
SCl₂ BCl₃
B)SCl₂ BCl₃ PCl₃ CCl₄
C)BCl₃ CCl₄ PCl₃ SCl₂
D)SCl₂ BCl₃ CCl₄ PCl₃
E)BCl₃ SCl₂ PCl₃ CCl₄

Question 41

The combustion of ethanol (CH₃CH₂OH, 46.1 g/mol) results in the formation of water and carbon dioxide. How many grams of carbon dioxide are produced when 46.1 g of ethanol burns?

A)88.0 g
B)44.0 g
C)176.0 g
D)22.0 g
E)11.0 g

Question 42

In a demonstration of the complete combustion of propane (C₃H₈) with oxygen (O₂), several balloons were prepared with various proportions by volume of propane and oxygen. The loudest explosion occurred for the balloon with the correct stoichiometric proportions of the gases. Which balloon had the loudest explosion? Note that the number of molecules of a gas is proportional to the volume of the gas at a given pressure and temperature.

A)1 portion propane to 1 portion oxygen
B)1 portion propane to 3 portions oxygen
C)1 portion propane to 4 portions oxygen
D)1 portion propane to 5 portions oxygen
E)2 portions propane to 3 portions oxygen

Question 43

The average adult exhales about 1.0 kg of carbon dioxide each day. How much oxygen is needed in metabolizing glucose (C₆H₁₂O₆, 180 g/mol) to make that much carbon dioxide?

A)180 g
B)1,800 g
C)360 g
D)730 g
E)1,500 g

Question 44

Phosphorus trichloride reacts with water to form phosphorous acid, H₃PO₃, and hydrochloric acid in the following unbalanced reaction. For each mole of phosphorous acid produced by this reaction, how many moles of HCl are produced?__ PCl₃ __H₂O __H₃PO₃ + __ HCl

A)1
B)2
C)3
D)4
E)5

Question 45

Respiration is to photosynthesis as ________

A)a lake is to an ocean.
B)a plane is to a car.
C)Canada is to North America.
D)summer is to winter.
E)a cake is to a pie.

Question 46

Which statement A-D regarding photosynthesis is not correct? In the process of photosynthesis ________

A)light energy is converted into carbon-based fuels.
B)oxygen is produced.
C)atmospheric carbon dioxide is consumed.
D)the sugar glucose is produced.
E)A-D are all correct.

Question 47

Balance the following combustion reaction and report the sum of the stoichiometric coefficients.__ C₄H₈S₂ __O₂ __CO₂ __H₂O __SO₃

A)16
B)17
C)18
D)19
E)20

Question 48

What are the stoichiometric coefficients for oxygen and water, respectively, in the balanced chemical reaction equation representing the combustion of butane (C₄H₁₀)?

A)4, 5
B)9, 5
C)13, 10
D) , 10
E)13, 5

Question 49

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C₁₆H₃₄. Write the balanced reaction equation for the combustion of C₁₆H₃₄, and report the sum of the stoichiometric coefficients.

A)4
B)120
C)76
D)83
E)117

Question 50

The combustion of heptane (C₇H₁₆) forms carbon dioxide and water. What is the stoichiometric coefficient for water in the balanced equation when 1 mol of heptane undergoes combustion?

A)6
B)
C)7
D)8
E)9

Question 51

If the combustion of fossil fuels adds about 5 $\times$ 10¹² kg of carbon to the atmosphere as CO₂ each year, how much oxygen is required to produce this amount of carbon dioxide?

A)about 1.3 10¹² kg
B)about 1.3 10¹³ kg
C)about 2.6 10¹² kg
D)about 2.6 10¹³ kg
E)about 6.7 10¹² kg

Question 52

Ozone (O₃) reacts with iodide (I^-) and water to form iodine (I₂), hydroxide (OH^-), and oxygen (O₂). Balance the following reaction equation and report the sum of the stoichiometric coefficients. O₃ I^- H₂O I₂ OH^- O₂

A)10
B)6
C)8
D)12
E)14

Question 53

Which statement A-D regarding the carbon cycle is not correct?

A)Petroleum, coal, and other carbon sediments are produced.
B)Respiration produces atmospheric carbon dioxide.
C)Water is a reactant in photosynthesis.
D)Forest fires are part of the carbon cycle.
E)A-D are all correct.

Question 54

One form of elemental sulfur is a ring of eight sulfur atoms. How many moles of molecular oxygen are consumed when one mole of this allotrope burns to make sulfur trioxide?

A)3
B)6
C)12
D)18
E)24

Question 55

The combustion of fossil fuels is the main anthropogenic source of carbon dioxide in the atmosphere. During the combustion of gasoline in automobile engines, oxygen reacts with hydrocarbons to produce carbon dioxide and water. Assume gasoline is octane (C₈H₁₈). Write the balanced reaction equation, and report the sum of the stoichiometric coefficients written as integers.

A)55
B)29
C)31
D)30
E)61

Question 56

Identify the set of stoichiometric coefficients that balances the reaction equation for the combustion of octane. C₈H₁₈ O₂ CO₂ H₂O

A)1, 25, 8, 9
B)1, 17, 8, 9
C)2, 34, 16, 18
D)2, 25, 16, 18
E)None of the above coefficients balance the reaction equation.

Question 57

Ammonia undergoes combustion to produce nitrogen monoxide and water, both as gases. Write the balanced equation for this reaction and report the sum of the stoichiometric coefficients, written as integers.

A)17
B)13
C)23
D)21
E)19

Question 58

Glucose (C₆H₁₂O₆) is oxidized by molecular oxygen to carbon dioxide and water. How many O₂ molecules are needed for each molecule of glucose that is oxidized?

A)1
B)2
C)6
D)12
E)18

Question 59

A fuel cell works on the same principle as a battery but is continually fed with fuel. In one fuel cell, methanol (CH₃OH) enters on one side of the unit and air enters on the other side. Both circulate past electrodes, and a chemical reaction occurs that produces electricity, plus carbon dioxide and water as byproducts. Which balanced chemical reaction equation best represents the reaction that occurs in this fuel cell?

A)CH₃OH CO₂ H₂O
B)CH₃OH CH₃ OH
C)CH₃OH CH₂ H₂O
D)CH₃OH O₂ CO₂ H₂O
E)2CH₃OH 3O₂ 2CO₂ 4H₂O

Question 60

Burning coal that contains sulfur releases sulfur dioxide gas into the atmosphere, where it combines with water to form sulfurous and sulfuric acid, thereby producing acid rain. Assume sulfur in coal is in the form of pyrite (FeS₂(s)), which reacts with molecular oxygen to produce Fe₂O₃(s) and SO₂(g). Write the balanced equation for this reaction and report the sum of the stoichiometric coefficients, written as integers.

A)16
B)14
C)23
D)25
E)18

Question 61

An iron ore, magnetite, contains only iron and oxygen. In refining 100.0 g of the ore, 72.35 g of iron are obtained. What is the empirical formula of the ore?

A)Fe₂O₃
B)FeO₂
C)Fe₂O₅
D)Fe₃O₄
E)FeO

Question 62

Metallic sodium was originally produced by the Deville process, where sodium carbonate and carbon black are heated to 1100 ^$\circ$ C to produce sodium (as a liquid at that temperature) and carbon monoxide gas, according to the following balanced equation. Na₂CO₃(s) 2C(s) 2Na(l) 3CO(g)
If 2.3 kg of sodium carbonate is heated, what is the maximum amount of sodium that can be produced?

A)0.50 kg
B)1.0 kg
C)1.5 kg
D)11 kg
E)21 kg

Question 63

Copper was the first metal to be produced from its ore because it is the easiest to smelt, that is, to refine by heating in the presence of carbon (hence the early occurrence of the Bronze Age). The ore was likely malachite (Cu₂(OH)₂CO₃). What is the mass percent of copper in malachite?

A)28.7%
B)45.2%
C)57.5%
D)40.3%
E)74.6%

Question 64

Baking ammonia or ammonium bicarbonate (NH₄HCO₃, 79.1 g/mol) is a leavening agent used in some older recipes. As it is heated, it breaks down into three gases: ammonia, water, and carbon dioxide. For each 20 g of baking ammonia heated (about 4 tsp), how many grams of carbon dioxide are produced?

A)15 g
B)7.5 g
C)11 g
D)22 g
E)20 g

Question 65

One form of asbestos called chrysotile is considered to be a human carcinogen. Mass analysis shows that the composition of chrysotile is 26.3% Mg, 20.2% Si, 1.45% H, and the remainder of the mass is oxygen. Determine the empirical formula of chrysotile.

A)MgSiHO₃
B)Mg₂Si₂H₂O₅
C)Mg₃Si₂H₄O₆
D)Mg₃Si₂H₄O₉
E)Mg₄Si₃H₅O₉

Question 66

Copper sulfate is a blue solid that is used to control algae growth. Solutions of copper sulfate that come in contact with the surface of galvanized (zinc-plated) steel pails undergo the following reaction that forms copper metal on the zinc surface. How many grams of zinc would react with 454 g (1 lb) of copper sulfate (160 g/mol)? CuSO₄(aq) Zn(s) Cu(s) ZnSO₄(aq)

A)467 g
B)186 g
C)93 g
D)234 g
E)454 g

Question 67

A compound known to contain platinum, nitrogen, and hydrogen was analyzed and found to contain 74.1% Pt and 21.3% N; the remainder was hydrogen. What is the empirical formula for the compound?

A)Pt(NH₃)₄
B)Pt(NH₃)₃
C)Pt₂(NH₃)₂
D)Pt(NH₄)₂
E)Pt(NH₃)₆

Question 68

Arizona was the site of a 400,000-acre wildfire in June 2002. How much carbon dioxide was produced by this fire? Assume that the density of carbon on the acreage was 10 kg/m² and that 50% of the biomass burned. (10,000 m² = 2.47 acre)

A)3 10¹⁰ kg
B)3 10⁶ kg
C)3 10³⁰ kg
D)3 10⁹ kg
E)3 10¹³ kg

Question 69

A range of organic molecules can undergo combustion. If pyridine (C₅H₅N) undergoes combustion through the following balanced chemical reaction, how much carbon dioxide can be produced when 3.2 g of pyridine reacts? 4C₅H₅N 27O₂
H₂O 20CO₂ 4NO

A)0.36 g
B)1.2 g
C)1.8 g
D)5.8 g
E)8.9 g

Question 70

Water can be separated into its elements according to the following equation by electrolysis. If 20.0 g of water is decomposed by this method, how much oxygen gas is produced? 2H₂O(l) 2H₂(g) O₂(g)

A)17.8 g
B)8.9 g
C)35.6 g
D)16.0 g
E)10.0 g

Question 71

Even though lead is toxic, lead compounds were used in ancient times as white pigments in cosmetics. What is the percentage of lead by mass in lead(IV) carbonate, Pb(CO₃)₂?

A)32.7%
B)20.7%
C)63.3%
D)77.5%
E)81.4%

Question 72

What mass of phosphoric acid (H₃PO₄, 98.0 g/mol) is produced from the reaction of 10.0 g of P₄O₁₀ (284 g/mol) with excess water?

A)10.9 g
B)40.0 g
C)10.0 g
D)13.8 g
E)2.50 g

Question 73

Baking soda (NaHCO₃, 84.0 g/mol) requires acids from other ingredients to generate the carbon dioxide needed to make bread rise. The following equation describes this reaction, where HB is some unspecified acid. If 20.4 g of baking soda are used in a recipe and enough acid is present for a complete reaction, how many moles of carbon dioxide are generated? HB NaHCO₃ H₂O CO₂ NaB

A)0.464 mol
B)0.334 mol
C)0.243 mol
D)0.204 mol
E)0.232 mol

Question 74

The average car emits 8.0 kg of carbon dioxide per gallon of combusted gas. What mass of gasoline (C₈H₁₈, 114.23 g/mol) was required to make that much carbon dioxide?

A)5.0 $\times$ 10^-3 kg
B)1.3 kg
C)2.6 kg
D)21 kg
E)170 kg

Question 75

The most abundant metal in Earth's crust is aluminum, found mostly in the form of clays. There are no economical routes for extracting aluminum from clay. However, bauxite ore, impure hydrated aluminum oxide, is found in hot, humid regions, such as Australia, Guinea, and Brazil, and it can be purified and refined to make the metal. After the first purification step, hydrated aluminum oxide (Al₂O₃ . xH₂O) is obtained. When 100.0 g of this solid were heated, and the water driven off, 65.36 g of Al₂O₃ remained. How many water molecules (x in the molecular formula) were there in the hydrate?

A)1
B)2
C)3
D)4
E)5

Question 76

Fool's Gold is the mineral pyrite (FeS₂). What is the mass percent of sulfur in pyrite?

A)36.44%
B)46.59%
C)49.09%
D)53.41%
E)63.56%

Question 77

Elemental analysis of the soot produced by a candle flame shows that it is 14.3% H and 85.7% C by mass. What is the empirical formula of this hydrocarbon?

A)CH
B)CH₂
C)C₂H
D)CH₃
E)C₂H₃

Question 78

Elemental analysis of the organic compound meta-xylene shows that it is 9.49% H and 90.51% C by mass. What is the empirical formula of this hydrocarbon?

A)CH
B)C₂H₃
C)C₃H₄
D)C₄H₅
E)C₅H₆

Question 79

A compound was analyzed and found to contain 25.24% S and 74.76% F. What is the empirical formula for the molecular compound?

A)SF
B)SF₂
C)SF₃
D)SF₅
E)S₂F₄

Question 80

Acetaminophen is a common medication used to treat pain and relieve fever. Mass analysis shows that the composition of acetaminophen is 63.56% C, 6.00% H, 9.27% N, and the remainder of the mass is oxygen. Determine the empirical formula of acetaminophen.

A)CHNO
B)C₈H₉NO₂
C)C₂H₂NO
D)C₃H₄N₂O₃
E)C₇H₇N₂O₂