Question 1

Lead(II) sulfide was once used in glazing earthenware. It will also react with hydrogen peroxide to form lead(II) sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II) sulfide?

Accepted Answer

A)  151 g 
B)  123 g 
C)  50.3 g 
D)  37.7 g 
E)  9.41 g

Question 2

Gadolinium oxide, a colorless powder which absorbs carbon dioxide from the air, contains 86.76 mass % Gd. Determine its empirical formula.

Accepted Answer

A)  Gd2O3 
B)  Gd3O2 
C)  Gd3O4 
D)  Gd4O3 
E)  GdO

Question 3

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) → 2CO(g)
Fe3O4(s) + 4CO(g) → 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

Question 4

Determine the percent composition of potassium dichromate, K2Cr2O7.

Accepted Answer

A)  17.5% K, 46.6% Cr, 35.9% O 
B)  29.8% K, 39.7% Cr, 30.5% O 
C)  36.5% K, 48.6% Cr, 14.9% O 
D)  37.2% K, 24.7% Cr, 38.1% O 
E)  None of these choices are correct.

Question 5

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

Accepted Answer

A) True 
 B)False

Question 6

Balance the following equation for the combustion of benzene: C6H6(l) + O2(g) → H2O(g) + CO2(g)

Accepted Answer

A)  C6H6(l) + 9O2(g) → 3H2O(g) + 6CO2(g) 
B)  C6H6(l) + 9O2(g) → 6H2O(g) + 6CO2(g) 
C)  2C6H6(l) + 15O2(g) → 6H2O(g) + 12CO2(g) 
D)  C6H6(l) + 15O2(g) → 3H2O(g) + 6CO2(g) 
E)  2C6H6(l) + 9O2(g) → 6H2O(g) + 12CO2(g)

Question 7

Magnesium fluoride is used in the ceramics and glass industry. What is the mass of 1.72 mol of magnesium fluoride?

Accepted Answer

A)  43.3 g 
B)  62.3 g 
C)  74.5 g 
D)  92.9 g 
E)  107 g

Question 8

Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain, and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.

Accepted Answer

A)  9.490 × 1025 Cr atoms 
B)  2.248 × 1024 Cr atoms 
C)  1.124 × 1024 Cr atoms 
D)  3.227 × 1023 Cr atoms 
E)  1.613 × 1023 Cr atoms

Question 9

How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH3? 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

Accepted Answer

A)  469.7 g 
B)  300.6 g 
C)  250.0 g 
D)  3.406 g 
E)  2.180 g

Question 10

In the combustion analysis of 0.1127 g of glucose (C6H12O6), what mass, in grams, of CO2 would be produced?

Accepted Answer

A)  0.0451 g 
B)  0.0825 g 
C)  0.1652 g 
D)  0.4132 g 
E)  1.466 g

Question 11

An important reaction sequence in the industrial production of nitric acid is the following: N2(g) + 3H2(g) → 2NH3(g)
4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l)
Starting from 20.0 mol of nitrogen gas in the first reaction, how many moles of oxygen gas are required in the second one?

Accepted Answer

A)  12.5 mol O2 
B)  20.0 mol O2 
C)  25.0 mol O2 
D)  50.0 mol O2 
E)  100. mol O2

Question 12

Calculate the molar mass of Ca(BO2)2·6H2O.

Accepted Answer

A)  273.87 g/mol 
B)  233.79 g/mol 
C)  183.79 g/mol 
D)  174.89 g/mol 
E)  143.71 g/mol

Question 13

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

Question 14

Calcium fluoride, CaF2, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Accepted Answer

A)  118.15 g/mol 
B)  99.15 g/mol 
C)  78.07 g/mol 
D)  59.08 g/mol 
E)  50.01 g/mol

Question 15

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO3)2.

Accepted Answer

A)  107 g 
B)  90.8 g 
C)  87.0 g 
D)  83.4 g 
E)  62.6 g

Question 16

The formula CH3O0.5 is an example of an empirical formula.

Accepted Answer

A) True 
 B)False

Question 17

How many grams of sodium fluoride (used in water fluoridation and manufacture of insecticides) are needed to form 485 g of sulfur tetrafluoride? 3SCl2(l) + 4NaF(s) → SF4(g) + S2Cl2(l) + 4NaCl(s)

Accepted Answer

A)  1940 g 
B)  1510 g 
C)  754 g 
D)  205 g 
E)  51.3 g

Question 18

Potassium chlorate (used in fireworks, flares, and safety matches) forms oxygen and potassium chloride when heated. KClO3(s) → KCl(s) + O2(g) [unbalanced]
How many grams of oxygen are formed when 26.4 g of potassium chlorate is heated?

Accepted Answer

A)  223 g 
B)  99.1 g 
C)  10.3 g 
D)  6.86 g 
E)  4.60 g

Question 19

Aluminum reacts with oxygen to produce aluminum oxide which can be used as an adsorbent, desiccant, or catalyst for organic reactions. 4Al(s) + 3O2(g) → 2Al2O3(s)
A mixture of 82.49 g of aluminum (  = 26.98 g/mol) and 117.65 g of oxygen (  = 32.00 g/mol) 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)  Oxygen is the limiting reactant; 19.81 g of aluminum remain. 
B)  Oxygen is the limiting reactant; 35.16 g of aluminum remain. 
C)  Aluminum is the limiting reactant; 16.70 g of oxygen remain. 
D)  Aluminum is the limiting reactant; 35.16 g of oxygen remain. 
E)  Aluminum is the limiting reactant; 44.24 g of oxygen remain.

Question 20

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. Determine its empirical formula.

Accepted Answer

A)  HNO 
B)  H2NO2 
C)  HN6O16 
D)  HN16O7 
E)  H2NO3

Exam 3: Stoichiometry of Formulas and Equations

Lead(II) sulfide was once used in glazing earthenware. It will also react with hydrogen peroxide to form lead(II) sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II) sulfide?

Gadolinium oxide, a colorless powder which absorbs carbon dioxide from the air, contains 86.76 mass % Gd. Determine its empirical formula.

Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

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

Balance the following equation for the combustion of benzene: C₆H₆(l) + O₂(g) → H₂O(g) + CO₂(g)

Magnesium fluoride is used in the ceramics and glass industry. What is the mass of 1.72 mol of magnesium fluoride?

Potassium dichromate, K₂Cr₂O₇, is used in tanning leather, decorating porcelain, and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K₂Cr₂O₇.

How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH₃? 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

In the combustion analysis of 0.1127 g of glucose (C₆H₁₂O₆) , what mass, in grams, of CO₂ would be produced?

An important reaction sequence in the industrial production of nitric acid is the following: N₂(g) + 3H₂(g) → 2NH₃(g) 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(l) Starting from 20.0 mol of nitrogen gas in the first reaction, how many moles of oxygen gas are required in the second one?

Calculate the molar mass of Ca(BO₂) ₂·6H₂O.

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.

Calcium fluoride, CaF₂, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO₃) ₂.

The formula CH₃O_0.5 is an example of an empirical formula.

How many grams of sodium fluoride (used in water fluoridation and manufacture of insecticides) are needed to form 485 g of sulfur tetrafluoride? 3SCl₂(l) + 4NaF(s) → SF₄(g) + S₂Cl₂(l) + 4NaCl(s)

Potassium chlorate (used in fireworks, flares, and safety matches) forms oxygen and potassium chloride when heated. KClO₃(s) → KCl(s) + O₂(g) [unbalanced] How many grams of oxygen are formed when 26.4 g of potassium chlorate is heated?

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. Determine its empirical formula.

Exam 3: Stoichiometry of Formulas and Equations

Lead(II) sulfide was once used in glazing earthenware. It will also react with hydrogen peroxide to form lead(II) sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II) sulfide?

Gadolinium oxide, a colorless powder which absorbs carbon dioxide from the air, contains 86.76 mass % Gd. Determine its empirical formula.

Determine the percent composition of potassium dichromate, K2Cr2O7.

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

Balance the following equation for the combustion of benzene: C6H6(l) + O2(g) → H2O(g) + CO2(g)

Magnesium fluoride is used in the ceramics and glass industry. What is the mass of 1.72 mol of magnesium fluoride?

Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain, and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.

How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH3? 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

In the combustion analysis of 0.1127 g of glucose (C6H12O6) , what mass, in grams, of CO2 would be produced?

An important reaction sequence in the industrial production of nitric acid is the following: N2(g) + 3H2(g) → 2NH3(g) 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l) Starting from 20.0 mol of nitrogen gas in the first reaction, how many moles of oxygen gas are required in the second one?

Calculate the molar mass of Ca(BO2) 2·6H2O.

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.

Calcium fluoride, CaF2, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO3) 2.

The formula CH3O0.5 is an example of an empirical formula.

How many grams of sodium fluoride (used in water fluoridation and manufacture of insecticides) are needed to form 485 g of sulfur tetrafluoride? 3SCl2(l) + 4NaF(s) → SF4(g) + S2Cl2(l) + 4NaCl(s)

Potassium chlorate (used in fireworks, flares, and safety matches) forms oxygen and potassium chloride when heated. KClO3(s) → KCl(s) + O2(g) [unbalanced] How many grams of oxygen are formed when 26.4 g of potassium chlorate is heated?

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. Determine its empirical formula.

Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

Balance the following equation for the combustion of benzene: C₆H₆(l) + O₂(g) → H₂O(g) + CO₂(g)

Potassium dichromate, K₂Cr₂O₇, is used in tanning leather, decorating porcelain, and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K₂Cr₂O₇.

How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH₃? 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

In the combustion analysis of 0.1127 g of glucose (C₆H₁₂O₆) , what mass, in grams, of CO₂ would be produced?

An important reaction sequence in the industrial production of nitric acid is the following: N₂(g) + 3H₂(g) → 2NH₃(g) 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(l) Starting from 20.0 mol of nitrogen gas in the first reaction, how many moles of oxygen gas are required in the second one?

Calculate the molar mass of Ca(BO₂) ₂·6H₂O.

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.

Calcium fluoride, CaF₂, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO₃) ₂.

The formula CH₃O_0.5 is an example of an empirical formula.

How many grams of sodium fluoride (used in water fluoridation and manufacture of insecticides) are needed to form 485 g of sulfur tetrafluoride? 3SCl₂(l) + 4NaF(s) → SF₄(g) + S₂Cl₂(l) + 4NaCl(s)

Potassium chlorate (used in fireworks, flares, and safety matches) forms oxygen and potassium chloride when heated. KClO₃(s) → KCl(s) + O₂(g) [unbalanced] How many grams of oxygen are formed when 26.4 g of potassium chlorate is heated?