Question 1

Calculate the mass in grams of 8.35 × 1022 molecules of CBr4.

Accepted Answer

A)  0.0217 g 
B)  0.139 g 
C)  7.21 g 
D)  12.7 g 
E)  46.0 g 
A)  0.0217 g 
B)  0.139 g 
C)  7.21 g 
D)  12.7 g 
E)  46.0 g E

Question 2

A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO2 absorber and a 0.0951 g increase in the mass of the H2O absorber. What is the empirical formula of the compound?

Accepted Answer

C₂₂H₃₅O₂

Question 3

How many protons are there in a molecule of adrenaline (C9H13NO3), a neurotransmitter and hormone?

Accepted Answer

A)  22 
B)  26 
C)  43 
D)  98 
E)  183 
A)  22 
B)  26 
C)  43 
D)  98 
E)  183 D

Question 4

Calculate the molar mass of (NH4)3AsO4.

Accepted Answer

A)  417.80 g/mol 
B)  193.03 g/mol 
C)  165.02 g/mol 
D)  156.96 g/mol 
E)  108.96 g/mol 
A)  417.80 g/mol 
B)  193.03 g/mol 
C)  165.02 g/mol 
D)  156.96 g/mol 
E)  108.96 g/mol

Question 5

Sulfur dioxide reacts with chlorine to produce thionyl chloride (used as a drying agent for inorganic halides) and dichlorine oxide (used as a bleach for wood, pulp, and textiles). SO2(g) + 2Cl2(g) F1F1F1S1F1F1F10 SOCl2(g) + Cl2O(g)
If 0.400 mol of Cl2 reacts with excess SO2, how many moles of Cl2O are formed?

Accepted Answer

A)  0.800 mol 
B)  0.400 mol 
C)  0.200 mol 
D)  0.100 mol 
E)  0.0500 mol 
A)  0.800 mol 
B)  0.400 mol 
C)  0.200 mol 
D)  0.100 mol 
E)  0.0500 mol

Question 6

Which of the following samples contains the greatest total number atoms?

Accepted Answer

A)  50.0 g of Li2O 
B)  75.0 g of CaO 
C)  200.0 g of Fe2O3 
D)  50.0 g of CO2 
E)  100.0 g of SO3 
A)  50.0 g of Li2O 
B)  75.0 g of CaO 
C)  200.0 g of Fe2O3 
D)  50.0 g of CO2 
E)  100.0 g of SO3

Question 7

The iodine "clock reaction" involves the following sequence of reactions occurring in a reaction mixture in a single beaker.
1) IO3-(aq) + 5I-(aq) + 6H+(aq) F1F1F1S1F1F1F10 3I2(aq) + 3H2O(l)
2) I2(aq) + 2S2O32-(aq) F1F1F1S1F1F1F10 2I-(aq) + S4O62-(aq)
The molecular iodine (I2) formed in reaction 1 is immediately used up in reaction 2, so that no iodine accumulates. What is the overall reaction occurring in this experiment?

Accepted Answer

A) IO3-(aq) + 3I-(aq) + 2S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 2I2(aq) + S4O62-(aq) + 3H2O(l) 
B) IO3-(aq) + 4S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 I-(aq) + 2S4O62-(aq) + 3H2O(l) 
C) IO3-(aq) + 6S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 I-(aq) + 3S4O62-(aq) + 3H2O(l) 
D) IO3-(aq) + I2(aq) + 8S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 3I-(aq) + 4S4O62-(aq) + 3H2O(l) 
E) IO3-(aq) + 2I2(aq) + 6S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 5I-(aq) + 3S4O62-(aq) + 3H2O(l) 
A) IO3-(aq) + 3I-(aq) + 2S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 2I2(aq) + S4O62-(aq) + 3H2O(l) 
B) IO3-(aq) + 4S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 I-(aq) + 2S4O62-(aq) + 3H2O(l) 
C) IO3-(aq) + 6S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 I-(aq) + 3S4O62-(aq) + 3H2O(l) 
D) IO3-(aq) + I2(aq) + 8S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 3I-(aq) + 4S4O62-(aq) + 3H2O(l) 
E) IO3-(aq) + 2I2(aq) + 6S2O32-(aq) + 6H+(aq) F1F1F1S1F1F1F10 5I-(aq) + 3S4O62-(aq) + 3H2O(l)

Question 8

Sodium bromate is used in a mixture which dissolves gold from its ores. Calculate the mass in grams of 4.68 mol of sodium bromate.

Accepted Answer

A)  706 g 
B)  482 g 
C)  383 g 
D)  32.2 g 
E)  0.0310 g 
A)  706 g 
B)  482 g 
C)  383 g 
D)  32.2 g 
E)  0.0310 g

Question 9

How many molecules of molecular oxygen react with four molecules of NH3 to form four molecules of nitrogen monoxide and six molecules of water?

Accepted Answer

A)  2 
B)  10 
C)  3 
D)  4 
E)  5 
A)  2 
B)  10 
C)  3 
D)  4 
E)  5

Question 10

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H, and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Accepted Answer

A)  C4H8O6 
B)  C5H10O5 
C)  C5H12O5 
D)  C6H12O4 
E)  none of the above 
A)  C4H8O6 
B)  C5H10O5 
C)  C5H12O5 
D)  C6H12O4 
E)  none of the above

Question 11

Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride.

Accepted Answer

A)  Potassium is the limiting reactant; 2.47 g of chlorine remain. 
B)  Potassium is the limiting reactant; 7.23 g of chlorine remain. 
C)  Chlorine is the limiting reactant; 4.64 g of potassium remain. 
D)  Chlorine is the limiting reactant; 2.70 g of potassium remain. 
E)  No limiting reagent: the reactants are present in the correct stoichiometric ratio. 
A)  Potassium is the limiting reactant; 2.47 g of chlorine remain. 
B)  Potassium is the limiting reactant; 7.23 g of chlorine remain. 
C)  Chlorine is the limiting reactant; 4.64 g of potassium remain. 
D)  Chlorine is the limiting reactant; 2.70 g of potassium remain. 
E)  No limiting reagent: the reactants are present in the correct stoichiometric ratio.

Question 12

Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH3(g) + O2(g) F1F1F1S1F1F1F10 P4O10(s) + H2O(g) [unbalanced]
Calculate the mass of P4O10(s) formed when 225 g of PH3 reacts with excess oxygen.

Accepted Answer

A)  1880 g 
B)  940. g 
C)  900. g 
D)  470 g 
E)  56.3 g 
A)  1880 g 
B)  940. g 
C)  900. g 
D)  470 g 
E)  56.3 g

Question 13

Methanol (CH4O) is converted to bromomethane (CH3Br) as follows:
 CH4O + HBr F1F1F1S1F1F1F10 CH3Br + H2O
If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Accepted Answer

A)  40.9% 
B)  82.6% 
C)  100.% 
D)  121% 
E)  245% 
A)  40.9% 
B)  82.6% 
C)  100.% 
D)  121% 
E)  245%

Question 14

In a blast furnace, elemental iron is produced from a mixture of coke (C), iron ore (Fe3O4), and other reactants. An important reaction sequence is 
2C(s) + O2(g) F1F1F1S1F1F1F10 2CO(g)
Fe3O4(s) + 4CO(g) F1F1F1S1F1F1F10 3Fe(l) + 4CO2(g)
How many moles of iron can be formed in this sequence when 1.00 mol of carbon, as coke, is consumed?

Accepted Answer

A)  6.00 mol Fe 
B)  3.00 mol Fe 
C)  1.33 mol Fe 
D)  1.25 mol Fe 
E)  0.750 mol Fe 
A)  6.00 mol Fe 
B)  3.00 mol Fe 
C)  1.33 mol Fe 
D)  1.25 mol Fe 
E)  0.750 mol Fe

Question 15

Household sugar, sucrose, has the molecular formula C12H22O11. What is the % of carbon in sucrose, by mass?

Accepted Answer

A)  26.7% 
B)  33.3% 
C)  41.4% 
D)  42.1% 
E)  52.8% 
A)  26.7% 
B)  33.3% 
C)  41.4% 
D)  42.1% 
E)  52.8%

Question 16

Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na2SO4.

Accepted Answer

A)  1.244 × 1023 O atoms 
B)  4.976 × 1023 O atoms 
C)  2.409 × 1024 O atoms 
D)  2.915 × 1024 O atoms 
E)  1.166 × 1025 O atoms 
A)  1.244 × 1023 O atoms 
B)  4.976 × 1023 O atoms 
C)  2.409 × 1024 O atoms 
D)  2.915 × 1024 O atoms 
E)  1.166 × 1025 O atoms

Question 17

In a correctly balanced equation, the number of reactant molecules must equal the number of product molecules.

Accepted Answer

A) True 
 B)False

Question 18

Copper(II) sulfate pentahydrate, CuSO4·5H2O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO4·5H2O.

Accepted Answer

A)  249.7 g 
B)  144.0 g 
C)  96.00 g 
D)  80.00 g 
E)  64.00 g 
A)  249.7 g 
B)  144.0 g 
C)  96.00 g 
D)  80.00 g 
E)  64.00 g

Question 19

Balance the following equation: 
C8H18O3(l) + O2(g) F1F1F1S1F1F1F10 H2O(g) + CO2(g)

Accepted Answer

A)  C8H18O3(l) + 8O2(g) F1F1F1S1F1F1F10 9H2O(g) + 8CO2(g) 
B)  C8H18O3(l) + 11O2(g) F1F1F1S1F1F1F10 9H2O(g) + 8CO2(g) 
C)  2C8H18O3(l) + 22O2(g) F1F1F1S1F1F1F10 9H2O(g) + 16CO2(g) 
D)  C8H18O3(l) + 13O2(g) F1F1F1S1F1F1F10 18H2O(g) + 8CO2(g) 
E)  2C8H18O3(l) + 17O2(g) F1F1F1S1F1F1F10 18H2O(g) + 16CO2(g) 
A)  C8H18O3(l) + 8O2(g) F1F1F1S1F1F1F10 9H2O(g) + 8CO2(g) 
B)  C8H18O3(l) + 11O2(g) F1F1F1S1F1F1F10 9H2O(g) + 8CO2(g) 
C)  2C8H18O3(l) + 22O2(g) F1F1F1S1F1F1F10 9H2O(g) + 16CO2(g) 
D)  C8H18O3(l) + 13O2(g) F1F1F1S1F1F1F10 18H2O(g) + 8CO2(g) 
E)  2C8H18O3(l) + 17O2(g) F1F1F1S1F1F1F10 18H2O(g) + 16CO2(g)

Question 20

A single atom of hydrogen has a mass of 1.0 amu, while a mole of hydrogen atoms has a mass of 1.0 g. Select the correct conversion factor between atomic mass units and grams.

Accepted Answer

A)  1 amu = 1 g exactly 
B)  1 amu = 6.0 × 1023 g 
C)  1 g = 6.0 × 1023 amu 
D)  1 g = 1.7 × 10-24 amu 
E)  none of the above 
A)  1 amu = 1 g exactly 
B)  1 amu = 6.0 × 1023 g 
C)  1 g = 6.0 × 1023 amu 
D)  1 g = 1.7 × 10-24 amu 
E)  none of the above

Exam 3: Stoichiometry of Formulas and Equations

Calculate the mass in grams of 8.35 × 1022 molecules of CBr4.

A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO2 absorber and a 0.0951 g increase in the mass of the H2O absorber. What is the empirical formula of the compound?

How many protons are there in a molecule of adrenaline (C9H13NO3), a neurotransmitter and hormone?

Calculate the molar mass of (NH4)3AsO4.

Sulfur dioxide reacts with chlorine to produce thionyl chloride (used as a drying agent for inorganic halides) and dichlorine oxide (used as a bleach for wood, pulp, and textiles). SO2(g) + 2Cl2(g)  SOCl2(g) + Cl2O(g) If 0.400 mol of Cl2 reacts with excess SO2, how many moles of Cl2O are formed?

Which of the following samples contains the greatest total number atoms?

Sodium bromate is used in a mixture which dissolves gold from its ores. Calculate the mass in grams of 4.68 mol of sodium bromate.

How many molecules of molecular oxygen react with four molecules of NH3 to form four molecules of nitrogen monoxide and six molecules of water?

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H, and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride.

Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH3(g) + O2(g)  P4O10(s) + H2O(g) [unbalanced] Calculate the mass of P4O10(s) formed when 225 g of PH3 reacts with excess oxygen.

Methanol (CH4O) is converted to bromomethane (CH3Br) as follows: CH4O + HBr  CH3Br + H2O If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Household sugar, sucrose, has the molecular formula C12H22O11. What is the % of carbon in sucrose, by mass?

Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na2SO4.

In a correctly balanced equation, the number of reactant molecules must equal the number of product molecules.

Copper(II) sulfate pentahydrate, CuSO4·5H2O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO4·5H2O.

Balance the following equation: C8H18O3(l) + O2(g)  H2O(g) + CO2(g)

A single atom of hydrogen has a mass of 1.0 amu, while a mole of hydrogen atoms has a mass of 1.0 g. Select the correct conversion factor between atomic mass units and grams.

Keys to the Study of Chemistry

The Components of Matter

The Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids, Solids, and Phase Changes

The Properties of Mixtures: Solutions and Colloids

Periodic Patterns in the Main Group Elements: Bonding, Structure, and Reactivity

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Elements in Nature and Industry

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

Calculate the mass in grams of 8.35 × 10²² molecules of CBr₄.

A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO₂ absorber and a 0.0951 g increase in the mass of the H₂O absorber. What is the empirical formula of the compound?

How many protons are there in a molecule of adrenaline (C₉H₁₃NO₃), a neurotransmitter and hormone?

Calculate the molar mass of (NH₄)₃AsO₄.

How many molecules of molecular oxygen react with four molecules of NH₃ to form four molecules of nitrogen monoxide and six molecules of water?

Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH₃(g) + O₂(g)  P₄O₁₀(s) + H₂O(g) [unbalanced] Calculate the mass of P₄O₁₀(s) formed when 225 g of PH₃reacts with excess oxygen.

Methanol (CH₄O) is converted to bromomethane (CH₃Br) as follows: CH₄O + HBr  CH₃Br + H₂O If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the % of carbon in sucrose, by mass?

Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na₂SO₄.

Copper(II) sulfate pentahydrate, CuSO₄·5H₂O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO₄·5H₂O.

Balance the following equation: C₈H₁₈O₃(l) + O₂(g)  H₂O(g) + CO₂(g)