Question 1

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH)2.

Accepted Answer

A)  3.28 mol 
B)  2.32 mol 
C)  0.431 mol 
D)  0.305 mol 
E)  0.200 mol 
A)  3.28 mol 
B)  2.32 mol 
C)  0.431 mol 
D)  0.305 mol 
E)  0.200 mol

Question 2

The percent yield can be determined by dividing the actual yield by the theoretical yield and multiplying this value by 100%.

Accepted Answer

A) True 
 B)False

Question 3

Which is a representation of a balanced chemical equation for the reaction of nitrogen gas and chlorine gas to form nitrogen trichloride?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 4

The limiting reactant is the reactant with the smallest initial mass.

Accepted Answer

A) True 
 B)False

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) → 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

What is the percent carbon in CH3CH2OH?

Accepted Answer

A)  13% 
B)  26% 
C)  35% 
D)  46% 
E)  52% 
A)  13% 
B)  26% 
C)  35% 
D)  46% 
E)  52%

Question 7

What is the theoretical yield of calcium oxide, in grams, that can be produced by the reaction of 5.61 g of V2O5 with 7.44 g of calcium to produce vanadium and calcium oxide? (Show all your work)

Accepted Answer

Question 8

What is the coefficient of H2O when the following equation is properly balanced with the smallest set of whole numbers? ________ PCl3(l) + ________ H2O(l) → ________ H3PO3(aq) + ________ HCl(aq)

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  5 
E)  None of these answers is correct. 
A)  1 
B)  2 
C)  3 
D)  5 
E)  None of these answers is correct.

Question 9

A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula.

Accepted Answer

A)  CrSi3 
B)  Cr2Si3 
C)  Cr3Si 
D)  Cr3Si2 
E)  Cr4Si3 
A)  CrSi3 
B)  Cr2Si3 
C)  Cr3Si 
D)  Cr3Si2 
E)  Cr4Si3

Question 10

Magnesium (used in the manufacture of light alloys) reacts with iron(III) chloride to form magnesium chloride and iron. A mixture of 41.0 g of magnesium and 175.0 g of iron(III) chloride is allowed to react. Identify the limiting reactant and determine the mass of the excess reactant present in the vessel when the reaction is complete.

Accepted Answer

A)  Limiting reactant is Mg; 7.4 g of FeCl3 remain. 
B)  Limiting reactant is Mg; 46.5 g of FeCl3 remain. 
C)  Limiting reactant is FeCl3; 1.7 g of Mg remain. 
D)  Limiting reactant is FeCl3; 37.8 g of Mg remain. 
E)  Limiting reactant is Mg; 134.0 g of FeCl3 remain. 
A)  Limiting reactant is Mg; 7.4 g of FeCl3 remain. 
B)  Limiting reactant is Mg; 46.5 g of FeCl3 remain. 
C)  Limiting reactant is FeCl3; 1.7 g of Mg remain. 
D)  Limiting reactant is FeCl3; 37.8 g of Mg remain. 
E)  Limiting reactant is Mg; 134.0 g of FeCl3 remain.

Question 11

How many grams of Cl2 can be prepared from the reaction of 16.0 g of MnO2 and 30.0 g of HCl according to the following balanced chemical equation? MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O

Accepted Answer

A)  6.52 g 
B)  7.29 g 
C)  13.0 g 
D)  14.6 g 
E)  58.4 g 
A)  6.52 g 
B)  7.29 g 
C)  13.0 g 
D)  14.6 g 
E)  58.4 g

Question 12

Proteins found in humans are polymers that consist of different combinations of 20 amino acids. Proline, one of the 20 amino acids, has the molecular formula, C5H9NO2. If a human protein has 25 proline monomers, how many carbon atoms from proline are present in the protein?

Accepted Answer

A)  4 C atoms 
B)  25 C atoms 
C)  40 C atoms 
D)  100 C atoms 
E)  125 C atoms 
A)  4 C atoms 
B)  25 C atoms 
C)  40 C atoms 
D)  100 C atoms 
E)  125 C atoms

Question 13

The insecticide DDT was formerly in widespread use, but now it is severely restricted owing to its adverse environmental effects. It is prepared as follows:
C2HCl3O + C6H5Cl → C14H9Cl5 + H2O [unbalanced]
chloral chlorobenzene DDT
Suppose 10.00 g of chloral was put in a container with 10.00 g of chlorobenzene and allowed to react.
a. What is the maximum amount, in mol, of DDT which could be formed?
b. What is the limiting reactant?
c. What is the percent yield, if 12.15 g of DDT is produced?

Accepted Answer

a. 0.0444 mol DDT 
b

Question 14

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

Accepted Answer

A) True 
 B)False

Question 15

What is the mass of 1.63 × 1021 atoms of silicon? (NA = 6.022 × 1023 mol-1)

Accepted Answer

A)  2.71 × 10-23 g 
B)  4.58 × 1022 g 
C)  28.08 g 
D)  1.04 × 104 g 
E)  7.60 × 10-2 g 
A)  2.71 × 10-23 g 
B)  4.58 × 1022 g 
C)  28.08 g 
D)  1.04 × 104 g 
E)  7.60 × 10-2 g

Question 16

What is the mass of 1.21 × 1020 atoms of sulfur? (NA = 6.022 × 1023 mol-1)

Accepted Answer

A)  3.88 × 1021 g 
B)  2.00 mg 
C)  32.06 g 
D)  6.44 mg 
E)  2.00 × 10-4 g 
A)  3.88 × 1021 g 
B)  2.00 mg 
C)  32.06 g 
D)  6.44 mg 
E)  2.00 × 10-4 g

Question 17

Many compounds can be represented with the same empirical formula.

Accepted Answer

A) True 
 B)False

Question 18

How many moles of aspirin, C9H8O4, are in a tablet that contains 325 mg of aspirin?

Accepted Answer

A)  0.00180 moles 
B)  0.555 moles 
C)  0.467 moles 
D)  0.357 moles 
E)  2.80 moles 
A)  0.00180 moles 
B)  0.555 moles 
C)  0.467 moles 
D)  0.357 moles 
E)  2.80 moles

Question 19

Which of the following is least helpful in balancing an equation?

Accepted Answer

A)  Use a balance sheet to keep track of the number of elements. 
B)  Try different coefficients and subscripts to balance the number of atoms. 
C)  Begin with elements that appear only once on each side of the equation. 
D)  Change only the coefficients to balance the number of atoms. 
A)  Use a balance sheet to keep track of the number of elements. 
B)  Try different coefficients and subscripts to balance the number of atoms. 
C)  Begin with elements that appear only once on each side of the equation. 
D)  Change only the coefficients to balance the number of atoms.

Question 20

What mass of excess reactant remains at the end of the reaction if 90.0 g of SO2 are mixed with 100.0 g of O2? 2SO2 + O2 → 2SO3

Accepted Answer

A)  10.0 g 
B)  12.5 g 
C)  22.5 g 
D)  55.0 g 
E)  77.5 g 
A)  10.0 g 
B)  12.5 g 
C)  22.5 g 
D)  55.0 g 
E)  77.5 g

Exam 3: Stoichiometry: Ratios of Combination

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH)2.

The percent yield can be determined by dividing the actual yield by the theoretical yield and multiplying this value by 100%.

Which is a representation of a balanced chemical equation for the reaction of nitrogen gas and chlorine gas to form nitrogen trichloride?

The limiting reactant is the reactant with the smallest initial mass.

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?

What is the percent carbon in CH3CH2OH?

What is the theoretical yield of calcium oxide, in grams, that can be produced by the reaction of 5.61 g of V2O5 with 7.44 g of calcium to produce vanadium and calcium oxide? (Show all your work)

What is the coefficient of H2O when the following equation is properly balanced with the smallest set of whole numbers? ________ PCl3(l) + ________ H2O(l) → ________ H3PO3(aq) + ________ HCl(aq)

A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula.

How many grams of Cl2 can be prepared from the reaction of 16.0 g of MnO2 and 30.0 g of HCl according to the following balanced chemical equation? MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O

Proteins found in humans are polymers that consist of different combinations of 20 amino acids. Proline, one of the 20 amino acids, has the molecular formula, C5H9NO2. If a human protein has 25 proline monomers, how many carbon atoms from proline are present in the protein?

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

What is the mass of 1.63 × 1021 atoms of silicon? (NA = 6.022 × 1023 mol-1)

What is the mass of 1.21 × 1020 atoms of sulfur? (NA = 6.022 × 1023 mol-1)

Many compounds can be represented with the same empirical formula.

How many moles of aspirin, C9H8O4, are in a tablet that contains 325 mg of aspirin?

Which of the following is least helpful in balancing an equation?

What mass of excess reactant remains at the end of the reaction if 90.0 g of SO2 are mixed with 100.0 g of O2? 2SO2 + O2 → 2SO3

Chemistry: the Central Science

Atoms, Molecules, and Ions

Reactions in Aqueous Solutions

Thermochemistry

Quantum Theory and the Electronic Structure of Atoms

Electron Configuration and the Periodic Table

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Molecular Geometry and Bonding Theories

Gases

Intermolecular Forces and the Physical Properties of Liquids and Solids

Modern Materials

Physical Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Entropy, Free Energy, and Equilibrium

Electrochemistry

Nuclear Chemistry

Environmental Chemistry

Coordination Chemistry

Metallurgy and the Chemistry of Metals

Nonmetallic Elements and Their Compounds

Organic Chemistry

Filters

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH)₂.

What is the percent carbon in CH₃CH₂OH?

What is the theoretical yield of calcium oxide, in grams, that can be produced by the reaction of 5.61 g of V₂O₅ with 7.44 g of calcium to produce vanadium and calcium oxide? (Show all your work)

What is the coefficient of H₂O when the following equation is properly balanced with the smallest set of whole numbers? PCl₃(l) + H₂O(l) → H₃PO₃(aq) + HCl(aq)

How many grams of Cl₂ can be prepared from the reaction of 16.0 g of MnO₂ and 30.0 g of HCl according to the following balanced chemical equation? MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

Proteins found in humans are polymers that consist of different combinations of 20 amino acids. Proline, one of the 20 amino acids, has the molecular formula, C₅H₉NO₂. If a human protein has 25 proline monomers, how many carbon atoms from proline are present in the protein?

What is the mass of 1.63 × 10²¹ atoms of silicon? (N_A = 6.022 × 10²³ mol^-1)

What is the mass of 1.21 × 10²⁰ atoms of sulfur? (N_A = 6.022 × 10²³ mol^-1)

How many moles of aspirin, C₉H₈O₄, are in a tablet that contains 325 mg of aspirin?

What mass of excess reactant remains at the end of the reaction if 90.0 g of SO₂ are mixed with 100.0 g of O₂? 2SO₂ + O₂→ 2SO₃