Deck 7: Stoichiometry Mass Relationships and Chemical Reactions

Question 1

Hydrogen peroxide decomposes to produce water and oxygen.Which of the following statements is NOT correct?
2H₂O₂ (l) $\rightarrow$ 2H₂O(l) + O₂ (g)

A)The products of the reaction are liquids.
B)Water and oxygen are the products of the reaction.
C)The chemical formula of hydrogen peroxide is H₂O₂.
D)The reaction is balanced.
E)Two molecules of H₂O and one molecule of O₂ are produced when two molecules of H₂O₂ react.

Answer 1

The products of the reaction are liquids.

Question 2

The combustion of butane (C₄H₁₀) forms carbon dioxide and water.What is the stoichiometric coefficient for oxygen in the balanced equation when 1 mol of butane undergoes combustion?

A)9

B)13

C) $\frac{13} {2}$

D) $\frac{9} {2}$

E)5

Answer 2

$\frac{13} {2}$

Question 3

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 all gaseous products equals the sum of the masses of the gaseous reactants.
E)The sum of the masses of solid products equals the sum of the masses of solid reactants.

Answer 3

The number of atoms of each kind is the same for the products as for the reactants.

Question 4

Air bags in cars inflate when an electrical spark activates sodium azide NaN ₃) so that it decomposes to sodium metal and nitrogen gas.In the balanced reaction equation, how many moles of N₂ gas are formed for each mole of NaN₃?

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

Question 5

Which statement about the following chemical reaction is NOT correct?
3 H₂ (g) + N₂ (g) $\rightarrow$ 2 NH₃ (g)

A)For every nitrogen molecule consumed, two molecules of ammonia are produced.
B)For every 6.06 g of H₂ consumed, two moles of NH₃ are produced.
C)If 34.0 g of NH₃ are produced, 28.0 g of N₂ were consumed.
D)In order for 56 g of N₂ to completely react, 18 g of H₂ would be required.
E)Three moles of nitrogen react with nine moles of hydrogen.

Question 6

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 7

Which relationship regarding the quantities of reactants and products associated with the following reaction is NOT correct?
6H₂ O(l) + P₄ O₁₀ (s) $\rightarrow$ 4 H₃ PO₄ (aq)

A)6 molecules + 1 molecule $\rightarrow$ 4 molecules
B)18 mol + 6 mol $\rightarrow$ 12 mol
C)324 g + 852 g $\rightarrow$ 1176 g
D)6x mol + x mol $\rightarrow$ 4x mol
E)y27 (g) + y71 (g) $\rightarrow$ y98 (g)

Question 8

Which statement regarding photosynthesis is FALSE?
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)Water is produced.

Question 9

Which statement regarding the carbon cycle is FALSE?

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)Combustion produces atmospheric oxygen.

Question 10

What are the stoichiometric coefficients for oxygen and water, respectively, in the balanced chemical reaction equation representing the combustion of butane (C ₄H₁₀)?

A)13, 10
B)9, 5
C)4, 5
D) $\frac{9}{2}$ , 10
E)13, 5

Question 11

Which statement about the following chemical reaction is NOT correct?
3 H₂ (g) + N₂ (g) $\rightarrow$ 2 NH₃ (g)

A)For every two moles of nitrogen consumed, three moles of ammonia are produced.
B)For every mole of nitrogen consumed, two 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 12

The acid-base reaction between phosphoric acid, H ₃PO₄, and calcium hydroxide, CaOH)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 13

Hydrogen peroxide decomposes to produce water and oxygen.Which relationship regarding the quantities of reactants and products associated with this reaction is NOT correct?
2H₂ O₂ (l) $\rightarrow$ 2H₂ O(l) + O₂ (g)

A)68.0 g $\rightarrow$ 36.0 g + 32.0 g
B)34.0 g $\rightarrow$ 18.0 g + 16.0 g
C)90.5 g (\rightarrow\) 47.9 g + 42.6g
D)2 x g $\rightarrow$ 2 x g + x g
E)y(34.0g) $\rightarrow$ y(18.0g) +(y / 2)(32g)

Question 14

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 (l) $\rightarrow$ 2 H₂O(l) +O₂(g)

A)2 molecules $\rightarrow$ 2 molecules + 1 molecule
B)2 mol $\rightarrow$ 2 mol+ 1 mol
C)68.0 g $\rightarrow$ 36.0 g + 32.0 g
D)2x mol $\rightarrow$ 2x mol + x mol
E)2 g $\rightarrow$ 2 g+ 1 g

Question 15

In an aqueous solution under basic conditions, ozone (O₃) reacts with iodide (I^-) and water to form iodine (I₂), hydroxide (OH^-), and oxygen (O₂).What is the sum of the stoichiometric coefficients in the balanced reaction equation? O₃(g) + I^-(aq) + H₂O(l) $\rightarrow$ I₂ (aq) + OH^-(aq) + O₂(g)

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

Question 16

Identify the set of stoichiometric coefficients that balance the reaction equation for the combustion of octane.
C₈ H₁₈ (l) +O₂ (g) $\rightarrow$ CO₂ (g) + H₂ O(l)

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 17

Which statement about the following chemical reaction is NOT correct? The molar masses of S₈, O₂, and SO₃ are 256, 32.0, and 80.1 g/mol, respectively.
S₈ (s)+ 12 O₂ (g) $\rightarrow$ 8 SO₃ (g)

A)1 mol S₈ produces 8 mol SO₃.
B)256 g S₈ requires 12 mol O₂ in order to completely react.
C)In order to produce 8 mol SO₃, 256 g S₈ and 192 g O₂ must react.
D)For every 6 mol O₂ consumed, 4 mol SO₃ are produced.
E)If 641 g SO₃ are produced, a total mass of 641 g of S₈ and O₂ must react.

Question 18

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 19

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 20

Fe₂O₃s) and powdered aluminum can react with great output of heat to form molten iron and Al ₂O₃.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 21

Suppose the combustion of fossil fuels adds about 8.0 * 10¹² kg of carbon to the atmosphere per year in the form of CO₂.How much oxygen gas is required to produce this amount of carbon dioxide?

A)about 2.1*10¹³ kg
B)about 5.8 * 10¹² kg
C)about 4.3 *10¹² kg
D)about 1.1 * 10¹³ kg
E)about 4.8 * 10¹³ kg

Question 22

Sulfuric acid reacts with a vanadium oxide compound according to the following unbalanced reaction.What are the coefficients in the balanced chemical equation in the order in which it is written?
H₂SO₄ (aq) + V₂O₃(s) $\rightarrow$ (V₂ SO₄ )₃)(s) + H₂O(l)

A)3, 1, 1, 3
B)3, 2, 3, 3
C)3, 1, 1, 6
D)3, 2, 2, 6
E)6, 3, 3, 12

Question 23

Potassium perchlorate (KClO₃) oxidizes sucrose (C₁₂H₂₂O₁₁) according to the following unbalanced reaction.What are the coefficients in the balanced chemical equation in the order in which it is written?
KClO₃ (s) + C₁₂ H₂₂ O₁₁(s) $\rightarrow$ KCl(s) + CO₂ (g) + H₂O (l)

A)4, 1, 4, 12, 11
B)4, 1, 4, 12, 22
C)2, 1, 2, 12, 11
D)8, 1, 8, 12, 11
E)8, 2, 8, 12, 11

Question 24

Extracting copper from sulfide ores can be performed by roasting the ore in oxygen, with a subsequent reaction of copper(I) oxide with carbon.Simplified chemical equations for these steps are shown below.Mathematically combine the two reactions to create an overall balanced equation that contains CU(s) as the only form of copper as a product.Eliminate like terms from your final equation and use the lowest whole-number coefficients possible.Select the statement regarding the overall balanced reaction that is FALSE.
2 Cu₂ S(s) +3O₂ (g) $\rightarrow$ 2 Cu₂ O(s) + 2 SO₂ (g)
Cu₂ O(s) + C(s) $\rightarrow$ 2 Cu(s) + CO(g)

A)The balanced reaction requires three moles of oxygen gas.
B)Two moles of copper result when two moles of carbon react.
C)Cu₂O does not appear in the final balanced equation.
D)Two moles of CO gas are produced in the overall balanced equation.
E)There are three reactants and three products in the overall balanced equation.

Question 25

What is the molar mass of phosphorus pentachloride PCl₅)?

A)177.3 g/mol
B)190.3 g/mol
C)208.2 g/mol
D)172.8 g/mol
E)202.8 g/mol

Question 26

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)the number of particles equal to the number of molecules in 1kg of water.
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 at the National Bureau of Standards.

Question 27

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 28

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)5930 mol
E)3.46 mol

Question 29

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 30

During a fermentation process, sucrose C₁₂H₂₂O₁₁) can react with water to form ethanol C₂H₅OH) and carbon dioxide gas.What is the sum of the coefficients in the balanced chemical equation?

A)8
B)10
C)12
D)14
E)16

Question 31

Ammonium nitrate NH₄NO₃) can decompose to form gaseous water, nitrogen, and oxygen.What is the sum of the coefficients in the balanced chemical equation?

A)5
B)6
C)7
D)8
E)9

Question 32

Chlorine atoms in the atmosphere can react with ozone.Mathematically combine the following two reactions to create an overall balanced equation with the lowest whole-number coefficients and select the statement that is FALSE.All chemical species in the reaction are gas-phase.
Cl + O₃ $\rightarrow$ Cl O + O₂
Cl O + O $\rightarrow$ Cl + O₂

A)Chlorine atoms do not appear in the overall balanced reaction.
B)There is a net conversion of O₃ to O₂.
C)ClO does not appear in the overall balanced reaction.
D)Two chlorine atoms can cause the production of two oxygen molecules.
E)Oxygen atoms are consumed by the overall reaction.

Question 33

Global carbon emissions in 2010 were estimated to be on the order of 9.0 * 10¹² metric tons of carbon 1 metric ton =1000 kg) in the form of CO₂.This is equivalent to _______ kg C.

A)about 2.5 * 10¹⁵
B)about 7.5 * 10¹⁴
C)about 2.0 * 10¹⁴
D)about 1.7 * 10¹³
E)about 1.2 *10¹⁵

Question 34

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?

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 35

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

A)1.00
B)2.00
C)3.01
D)6.01
E)9.02

Question 36

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)2 mol carbon monoxide
E)All of these contain the same number of atoms.

Question 37

Copper(II) sulfate (CuSO₄) can be used to control algae growth.Aqueous CuSO₄ solutions that come in contact with the surface of galvanized (zinc-plated) steel pails undergo the following reaction:
CuSO₄ (aq) +Zn(s) $\rightarrow$ Cu(s) +ZnSO₄ (aq)
How many grams of zinc would react with 454 g (1 lb) of CuSO₄ (159.61 g/mol)?

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

Question 38

A gallon of water has a mass of 3.79 kg.How many moles of water is this?

A)2.10 *10² mol
B)0.210 mol
C)68.3 mol
D)6.83 * 10⁴ mol
E)386 mol

Question 39

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C ₁₆H₃₄.Write the balanced reaction equation for the combustion of C ₁₆H₃₄ and report the sum of the stoichiometric coefficients.

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

Question 40

In one type of fuel cell, methanol CH₃OH) enters on one side of the unit and air enters on the other side.Both circulate past electrodes and chemically react to produce carbon dioxide and water along with electricity.Which chemical equation best represents the reaction that occurs?

A)CH₃ OH(l) $\rightarrow$ CO₂ (g) + 2 H₂ O(l)
B)2 CH₃ OH(l) + 3 O₂ (g) $\rightarrow$ 2 CO₂ (g) + 4 H₂ O(l)
C)CH₃ OH(l) $\rightarrow$ CH₂ (g) + H₂ O(l)
D)CH₃ OH(l) +N₂(g) $\rightarrow$ CH₃(g) + NO(g)
E)CH₃ OH(l) +O₂(g) $\rightarrow$ CO₂(g) + H₂O(l)

Question 41

The average adult exhales about 1.0 kg of carbon dioxide each day.How much oxygen is needed in metabolizing glucose C₆H₁₂O₆, 180.16 g/mol) to make that much carbon dioxide?

A)180 g
B)1800 g
C)360 g
D)730 g
E)1500 g

Question 42

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C ₁₆H₃₄.How many mL of C₁₆H₃₄ are needed to react with 1.00 mol O₂? The density of C₁₆H₃₄ is 0.773 g/mL and its molar mass is 226.43 g/mol.

A)9.23 mL
B)12.0 mL
C)0.561 mL
D)4.61 mL
E)0.140 mL

Question 43

The most abundant metal in Earth's crust is aluminum, found mostly in the form of clays.Bauxite ore, impure hydrated aluminum oxide, 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 was 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 44

The average adult exhales about 1.0 kg of carbon dioxide each day.How much glucose C₆H₁₂O₆, 180.16 g/mol) is consumed to make that much carbon dioxide?

A)3.8 kg
B)4.1 kg
C)0.43 kg
D)0.68 kg
E)0.18 kg

Question 45

As ammonium hydrogen carbonate NH₄HCO₃, 79.6 g/mol) is heated, it breaks down into three gases: ammonia, water, and carbon dioxide.For each 20.0 g of ammonium hydrogen carbonate heated about 4 tsp), how many grams of carbon dioxide are produced?

A)15.9 g
B)6.67 g
C)5.06 g
D)11.1 g
E)20.0 g

Question 46

How much CO₂ is produced by a car driven 20 * 10⁴ mi in one year? Assume the following:
• A car gets 20.0 mi/4.0 L of gasoline.
• Gasoline has the chemical formula of octane: C₈H₁₈.
• One liter of gasoline has a mass of 0.80 kg.
• Gasoline is completely burned to carbon dioxide and water.

A)1.5 * 10³ kg
B)9.9 * 10³ kg
C)1.5 * 10⁴ kg
D)2.0 * 10⁴ kg
E)4.9 * 10³ kg

Question 47

Metallic chromium can be obtained from the mineral chromite (FeCr₂O₄).What is the mass percent of chromium in chromite?

A)46.46%
B)61.90%
C)23.23%
D)30.26%
E)41.99%

Question 48

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.The ore was likely malachite [Cu2OH)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 49

Han purple, a synthetic inorganic pigment developed in China in ancient times, has the chemical formula BaCuSi₂O₆.What is its percent by mass silicon?

A)18.0%
B)15.9%
C)27.2%
D)38.9%
E)7.96%

Question 50

Assuming complete combustion, how many grams of butane C₄H₁₀) would be required to consume 32.0 g O₂?

A)1.82 g
B)16.6 g
C)8.30 g
D)4.47 g
E)8.94 g

Question 51

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C ₁₆H₃₄.How many grams of O₂ are needed to react with 0.500 mol C₁₆H₃₄?

A)458 g
B)392 g
C)784 g
D)295 g
E)196 g

Question 52

If 20.0 kg CO₂ are produced from the combustion of butane C₄H₁₀), calculate the mass of oxygen gas that was consumed.

A)23.6 kg
B)18.2 kg
C)11.8 kg
D)739 g
E)454 g

Question 53

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 54

Aluminum can form clusters that behave similarly to certain atoms.The "superatom," Al₁₃, is thought to mimic chlorine.Suppose you create a process that generates KAl ₁₃ 389.86 g/mol) and oxygen gas from aluminum oxide 101.96 g/mol) and potassium metal.How many grams of KAl₁₃ could be produced by the reaction of 102 g of Al₂O₃? You will need to write a balanced chemical reaction.

A)390.g
B)97.5 g
C)60.0 g
D)15.00 g
E)141 g

Question 55

The space shuttle uses liquid hydrogen and liquid oxygen to produce thrust for liftoff in the following reaction: 2H₂ (l) +O₂ (l) $\rightarrow$ 2H₂ O(g)
If the liquid oxygen supply is set to provide 420 kg/s during a launch, what does the rate of liquid hydrogen supply need to be in kilograms per second?

A)840 kg/s
B)210 kg/s
C)106 kg/s
D)53.1kg/s
E)63.4 kg/s

Question 56

Which of the following samples contains the fewest number of molecules? H is used as the symbol for hydrogen-1, and D is used as the symbol for hydrogen-2.

A)42 g of D₂O
B)two moles of H₂O
C)two moles of D₂O
D)36 g of H₂O
E)39 g of D₂O

Question 57

Hydrogen peroxide (H₂O₂) decomposes catalytically in the presence of metal ions and enzymes called peroxidases.If a 250 mL bottle of hydrogen peroxide solution containing 3.0% H ₂O₂ (by mass) decomposes completely, how many liters of oxygen gas will it generate? Assume that 1 mol of gas occupies a volume of 22.4 L and that the density of the solution is 1.0 g/mL.The reaction is
2H₂ O₂ (aq) $\rightarrow$ 2H₂ O(l) +O₂ (g)

A)2.5 L
B)4.9 L
C)9.9 L
D)7.4 L
E)0.22 L

Question 58

The combustion of ethanol CH₃CH₂OH, 46.7 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)88.1 g
B)44.0 g
C)176 g
D)22.0 g
E)11.0 g

Question 59

How many grams of CO₂ would result from the complete combustion of 4.00 mol butane C₄H₁₀)?

A)24.2 g
B)176 g
C)704 g
D)96.9 g
E)1410 g

Question 60

How many moles of chlorine are in 25.0 g of calcium chloride CaCl₂)?

A)0.705 mol
B)0.451 mol
C)0.331 mol
D)0.225 mol
E)0.676 mol

Question 61

Which of the following statements regarding mass spectrometry is NOT true?

A)Mass spectrometers ionize molecules.
B)Mass spectrometry can be used to determine empirical and molecular formulas.
C)The height intensity) of the signal observed is proportional to the number of ions at that mass-to-charge ratio.
D)The signal detected at the highest mass-to-charge ratio is often the smallest fragment of the molecule.
E)Distinctive fragmentation patterns can be used to identify molecules.

Question 62

A uranium oxide compound is found to be 84.80% U by mass.What is the empirical formula for the compound?

A)U₂O₅
B)UO₃
C)U₃O₈
D)UO₂
E)UO₄

Question 63

Analysis of two uranium fluoride compounds yields the following data: Compound I is 75.80% U by mass; compound II has an F-to-U mass ratio that is 1.5 times that of compound I.What is the empirical formula for compound II?

A)UF₄
B)UF₆
C)U₂F₃
D)UF₃
E)UF₂

Question 64

Phthalocyanine is a large molecule used in printing inks and dyes.Elemental analysis showed that it consists of 74.69% C, 3.525% H, and 21.77 % N and has a molar mass of 514.54 g/mol.What is its molecular formula?

A)C₁₆H₉N₄
B)C₃0H₈N10
C)C₃2H18N8
D)C₃₂H₄N₉
E)C16H18N4

Question 65

Ibuprofen is 75.69% C, 8.80% H, and 15.51% O by mass.What is its empirical formula?

A)C₆H₉O
B)C₉H₉O₂
C)C₇H₁₈O₂
D)C₇H₉O₂
E)C₁₃H₁₈O₂

Question 66

A gas that is produced when fruit ripens contains 85.62% C and 14.38% H by mass.The molecular mass was found to be twice the empirical formula unit molecular mass.What is the molecular formula of this gas?

A)CH₂
B)C₂H₂
C)C₂H₄
D)C₂H₆
E)C₄H₄

Question 67

A compound containing bromine and fluorine used in the production of UF₆ is 58.37% Br by mass.What is the empirical formula for the compound?

A)BrF
B)Br₂F₃
C)BrF₃
D)BrF₅
E)Br₃F₂

Question 68

Which of the following does NOT share the same empirical formula as the others?

A)formaldehyde, CH₂O
B)acetic acid, CH₃COOH
C)lactic acid, CH₃CHOH)COOH
D)butyric acid, CH₃CH₂CH₂COOH
E)glucose, C₆H₁₂O₆

Question 69

The empirical formula for buckminsterfullerene is C₁, and its molar mass is 720.6 g/mol.What is its molecular formula?

A)C₆₀
B)C₇₂
C)C₁₂
D)C₁
E)C₇₂₀

Question 70

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)PtNH₃)₄
B)PtNH₃)₃
C)Pt₂NH₃)₂
D)PtNH₄)₂
E)PtNH₃)₆

Question 71

A hydrocarbon is found to be 85.63% C by mass.What is its empirical formula?

A)CH
B)CH₂
C)CH₃
D)C₂H
E)CH₄

Question 72

When are an empirical formula and a molecular formula the same?

A)always
B)when the mass of the empirical formula unit is equal to the molecular mass
C)when the mass percentages of all of the elements in the two formulas are the same
D)never
E)when the molecular mass is an integer multiple of formula unit mass

Question 73

Licopene, a red pigment found in tomatoes, has the empirical formula C₅H₇, and its molecular mass is found to be approximately 537 amu.How many empirical units are in the actual molecular formula?

A)1
B)2
C)4
D)8
E)10

Question 74

Paris green is a highly toxic emerald green compound with the formula Cu(C₂H₃O₂ )2 . 3Cu(AsO₂ )₂ .What is its percent by mass arsenic?

A)31.99%
B)14.78%
C)22.17%
D)7.389%
E)44.34%

Question 75

A 2.00 g sample of methamphetamine was found to contain 1.61 g C, 0.203 g H, and 0.188 g N.What is its empirical formula?

A)C₁₀H₁₅N
B)C₄H₆N
C)C₄H₉N
D)C₁₃H₂₀N
E)C₈H₁₀N

Question 76

Hydroxylamine contains 42.41% N and 9.15% H by mass, with the remainder being oxygen.Determine its empirical formula.

A)N₁₄H₃O₁₆
B)N_4.6HO_5.3
C)N₅HO₅
D)N₃H₉O
E)NH₃O

Question 77

Alkanes share a general chemical formula of Cn H₂n+2 .What is n of an alkane with a molar mass in the range of 140-145 g/mol?

A)10
B)9
C)8
D)11
E)12

Question 78

A hydrocarbon molecule contains twice as many hydrogen atoms as carbon atoms.Its molar mass is 84.15 g/mol.What is the molecular formula for the hydrocarbon?

A)C₇H₁₄
B)C₆H₁₂
C)C₅H₁₀
D)C₈H₁₆
E)CH₂

Question 79

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 80

Caffeine has an elemental analysis of 49.48% C, 5.190% H, 16.47% O, and 28.85% N.It has a molar mass of 194.19 g/mol.What is the molecular formula of caffeine?

A)C₄H₅N₂O
B)C₈H₁₀N₄O₂
C)C₁₀H14N₂O₂
D)C₆H₆NO₂
E)C₅H₇NO