Question 1

When the following equation is balanced, the coefficient of C₃H₈O₃ is __________. C₃H₈O₃ (g)+ O₂ (g)→ CO₂ (g)+ H₂O (g) A)1 B)2 C)3 D)7 E)5

Accepted Answer

The balanced equation is C₃H₈O₃ (g)+ 2O₂ (g)→ CO₂ (g)+ 2H₂O (g). The coefficient of O₂ (g) is 2.

Question 2

When the following equation is balanced, the coefficient of H₃PO₄ is __________. H₃PO₄ (aq)+ NaOH (aq)→ Na₃PO₄ (aq)+ H₂O (l) A)1 B)2 C)3 D)4 E)0

Accepted Answer

The equation is already balanced as written, with all elements having the same number of atoms on both sides of the equation.

Question 3

When the following equation is balanced, the coefficient of Al₂O₃ is __________. Al₂O₃ (s)+ C (s)+ Cl₂ (g)→ AlCl₃ (s)+ CO (g) A)1 B)2 C)3 D)4 E)5

Accepted Answer

To balance the equation, start with the element that appears in the least number of compounds, which is often Aluminum (Al) in this case. The equation initially reads as Al2O3(s) + C(s) + Cl2(g) → AlCl3(s) + CO(g). Since Aluminum and Chlorine appear in a 1:3 ratio in AlCl3, and there are 2 Aluminum atoms in Al2O3, you need 2 Al2O3 to provide 4 Al atoms, which will react with 6 Cl2 to form 4 AlCl3. Carbon (C) and Oxygen (O) from CO balance last, ensuring the equation is stoichiometrically correct. The balanced equation is 2 Al2O3(s) + 3 C(s) + 6 Cl2(g) → 4 AlCl3(s) + 3 CO(g), making the coefficient of Al2O3 2.

Question 4

When the following equation is balanced, the coefficient of H₂ is __________. K (s)+ H₂O (l)→ KOH (aq)+ H₂ (g) A)1 B)2 C)3 D)4 E)5

Accepted Answer

The balanced chemical equation is K (s) + H2O (l) → KOH (aq) + H2 (g), with all species having a coefficient of 1, including H2O.

Question 5

There are ________ oxygen atoms in 30 molecules of C₂₀H₄₂S₃O₂. A)6.0 x 10²³ B)1.8 x 10²⁵ C)3.6 x 10²⁵ D)1.2 x 10²⁴ E)60

Accepted Answer

Each molecule of C20H42S3O2 contains 2 oxygen atoms. Therefore, 30 molecules contain 30 x 2 = 60 oxygen atoms.

Question 6

Which hydrocarbon pair below have identical mass percentage of C? A)C₃H₄ and C₃H₆ B)C₂H₄ and C₃H₄ C)C₂H₄ and C₄H₂ D)C₂H₄ and C₃H₆ E)none of the above

Accepted Answer

The answer of Which hydrocarbon pair below have identical mass...

Question 7

When the following equation is balanced, the coefficient of Al is __________. Al (s)+ H₂O (l)→ Al(OH)₃ (s)+ H₂ (g) A)1 B)2 C)3 D)5 E)4

Accepted Answer

Al (s) + 2H₂O (l) → Al(OH)₃ (s) + H₂ (g) The balanced equation requires 2 moles of H2SO4 to react with 1 mole of Al, so the coefficient of Al is 1 and the coefficient of H2SO4 is 2. Therefore, the answer is B.

Question 8

When the following equation is balanced, the coefficient of H₂S is __________. FeCl₃ (aq)+ H₂S (g)→ Fe₂S₃ (s)+ HCl (aq) A)1 B)2 C)3 D)5 E)4

Accepted Answer

The coefficient of H₂S is 3 when the equation is balanced. This is because there are three sulfur atoms on the left side of the equation (in H₂S), and to balance the sulfur atoms on the right side of the equation (in Fe₂S₃), we need to have 3 copies of H₂S.

Question 9

A sulfur oxide is 50.0% by mass sulfur. This molecular formula could be __________. A)SO B)SO₂ C)S₂O D)S₂O₄ E)either SO₂ or S₂O₄

Accepted Answer

The answer of A sulfur oxide is 50.0% by mass...

Question 10

When the following equation is balanced, the coefficient of H₂SO₄ is __________. H₂SO₄ (aq)+ NaOH (aq)→ Na₂SO₄ (aq)+ H₂O (l) A)1 B)2 C)3 D)4 E)0.5

Accepted Answer

The equation is already balanced as written, with all elements having the same number of atoms on both sides of the equation. Therefore, the coefficient of $HSO_4^-$ is 1.

Question 11

When the following equation is balanced, the coefficient of HNO₃ is __________. HNO₃ (aq)+ CaCO₃ (s)→ Ca(NO₃)₂ (aq)+ CO₂ (g)+ H₂O (l) A)1 B)2 C)3 D)5 E)4

Accepted Answer

The balanced equation is: 2 HNO₃(aq) + CaCO₃(s) → Ca(NO₃)₂(aq) + CO₂(g) + 2 H₂O(l) Therefore, the coefficient of HNO₃ is 2.

Question 12

Propane (C₃H₈)reacts with oxygen in the air to produce carbon dioxide and water. In a particular experiment, 38.0 grams of carbon dioxide are produced from the reaction of 22.05 grams of propane with excess oxygen. What is the % yield in this reaction? A)38.0 B)57.6 C)66.0 D)86.4 E)94.5

Accepted Answer

The answer of Propane (C₃H₈)reacts with oxygen in the air...

Question 13

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO₃ are produced by the reaction of 5.0 grams of O₂ with 6.0 grams of S. What is the % yield of SO₃ in this experiment? S (s)+ O₂ (g)→ SO₃ (g)(not balanced) A)32 B)63 C)75 D)95 E)99

Accepted Answer

The answer of Sulfur and oxygen react to produce sulfur...

Question 14

When the following equation is balanced, the coefficient of HCl is __________. CaCO₃ (s)+ HCl (aq)→ CaCl₂ (aq)+ CO₂ (g)+ H₂O (l) A)1 B)2 C)3 D)4 E)0

Accepted Answer

To balance the equation, we need two HCl molecules on the left side to react with one CaCO3 molecule. Therefore, the coefficient of HCl is 2.

Question 15

A nitrogen oxide is 63.65% by mass nitrogen. The molecular formula could be __________. A)NO B)NO₂ C)N₂O D)N₂O₄ E)either NO₂ or N₂O₄

Accepted Answer

Since the nitrogen oxide is 63.65% nitrogen by mass, we can assume that there is 1 nitrogen atom in the molecular formula. This leaves us with two possible formulas: NO or N2O. To determine which one is correct, we can calculate the percent composition of each formula. NO has a percent composition of 63.64% nitrogen and 36.36% oxygen. N2O has a percent composition of 44.44% nitrogen and 55.56% oxygen. Since the given nitrogen oxide is closer in percent composition to NO, the molecular formula is likely N₂O, which simplifies to NO2. Therefore, the correct answer is C.

Question 16

When the following equation is balanced, the coefficient of H₂ is __________. CO (g)+ H₂ (g)→ H₂O (g)+ CH₄ (g) A)1 B)2 C)3 D)4 E)0

Accepted Answer

The answer of When the following equation is balanced, the...

Question 17

When the following equation is balanced, the coefficient of H₂O is __________. Ca (s)+ H₂O (l)→ Ca(OH)₂ (aq)+ H₂ (g) A)1 B)2 C)3 D)5 E)4

Accepted Answer

In order to balance the equation, we need to have two molecules of H₂O on the left side of the equation to match with two molecules of H₂ on the right side. Therefore, the coefficient of H₂O is 2.

Question 18

When the following equation is balanced, the coefficients are __________. NH₃ (g)+ O₂ (g)→ NO₂ (g)+ H₂O (g) A)1, 1, 1, 1 B)4, 7, 4, 6 C)2, 3, 2, 3 D)1, 3, 1, 2 E)4, 3, 4, 3

Accepted Answer

The balanced equation will have the same number of atoms of each element on both the reactant and product sides. To achieve this, we need 4 moles of NH₃ and 7 moles of O₂ on the reactant side, and 4 moles of NO₂ and 6 moles of H₂O on the product side. Therefore, the coefficients are 4, 7, 4, 6.

Question 19

When the following equation is balanced, the coefficient of O₂ is __________. C₂H₄O (g)+ O₂ (g)→ CO₂ (g)+ H₂O (g) A)2 B)3 C)4 D)5 E)1

Accepted Answer

The answer of When the following equation is balanced, the...

Question 20

When the following equation is balanced, the coefficients are __________. Al(NO₃)₃ + Na₂S → Al₂S₃ + NaNO₃ A)2, 3, 1, 6 B)2, 1, 3, 2 C)1, 1, 1, 1 D)4, 6, 3, 2 E)2, 3, 2, 3

Accepted Answer

The balanced equation is 2 Al(NO3)3 + 3 Na2S → Al2S3 + 6 NaNO3, which corresponds to coefficients 2, 3, 1, 6.

Quiz 3: Stoichiometry: Calculations With Chemical Formulas and Equations

When the following equation is balanced, the coefficient of C₃H₈O₃ is __________. C₃H₈O₃ (g) + O₂ (g) → CO₂ (g) + H₂O (g)

When the following equation is balanced, the coefficient of H₃PO₄ is __________. H₃PO₄ (aq) + NaOH (aq) → Na₃PO₄ (aq) + H₂O (l)

When the following equation is balanced, the coefficient of Al₂O₃ is __________. Al₂O₃ (s) + C (s) + Cl₂ (g) → AlCl₃ (s) + CO (g)

When the following equation is balanced, the coefficient of H₂ is __________. K (s) + H₂O (l) → KOH (aq) + H₂ (g)

There are ________ oxygen atoms in 30 molecules of C₂₀H₄₂S₃O₂.

Which hydrocarbon pair below have identical mass percentage of C?

When the following equation is balanced, the coefficient of Al is __________. Al (s) + H₂O (l) → Al(OH) ₃ (s) + H₂ (g)

When the following equation is balanced, the coefficient of H₂S is __________. FeCl₃ (aq) + H₂S (g) → Fe₂S₃ (s) + HCl (aq)

A sulfur oxide is 50.0% by mass sulfur. This molecular formula could be __________.

When the following equation is balanced, the coefficient of H₂SO₄ is __________. H₂SO₄ (aq) + NaOH (aq) → Na₂SO₄ (aq) + H₂O (l)

When the following equation is balanced, the coefficient of HNO₃ is __________. HNO₃ (aq) + CaCO₃ (s) → Ca(NO₃) ₂ (aq) + CO₂ (g) + H₂O (l)

Propane (C₃H₈) reacts with oxygen in the air to produce carbon dioxide and water. In a particular experiment, 38.0 grams of carbon dioxide are produced from the reaction of 22.05 grams of propane with excess oxygen. What is the % yield in this reaction?

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO₃ are produced by the reaction of 5.0 grams of O₂ with 6.0 grams of S. What is the % yield of SO₃ in this experiment? S (s) + O₂ (g) → SO₃ (g) (not balanced)

When the following equation is balanced, the coefficient of HCl is __________. CaCO₃ (s) + HCl (aq) → CaCl₂ (aq) + CO₂ (g) + H₂O (l)

A nitrogen oxide is 63.65% by mass nitrogen. The molecular formula could be __________.

When the following equation is balanced, the coefficient of H₂ is __________. CO (g) + H₂ (g) → H₂O (g) + CH₄ (g)

When the following equation is balanced, the coefficient of H₂O is __________. Ca (s) + H₂O (l) → Ca(OH) ₂ (aq) + H₂ (g)

When the following equation is balanced, the coefficients are __________. NH₃ (g) + O₂ (g) → NO₂ (g) + H₂O (g)

When the following equation is balanced, the coefficient of O₂ is __________. C₂H₄O (g) + O₂ (g) → CO₂ (g) + H₂O (g)

When the following equation is balanced, the coefficients are __________. Al(NO₃) ₃ + Na₂S → Al₂S₃ + NaNO₃

Quiz 3: Stoichiometry: Calculations With Chemical Formulas and Equations

When the following equation is balanced, the coefficient of C3H8O3 is __________. C3H8O3 (g) + O2 (g) → CO2 (g) + H2O (g)

When the following equation is balanced, the coefficient of H3PO4 is __________. H3PO4 (aq) + NaOH (aq) → Na3PO4 (aq) + H2O (l)

When the following equation is balanced, the coefficient of Al2O3 is __________. Al2O3 (s) + C (s) + Cl2 (g) → AlCl3 (s) + CO (g)

When the following equation is balanced, the coefficient of H2 is __________. K (s) + H2O (l) → KOH (aq) + H2 (g)

There are ________ oxygen atoms in 30 molecules of C20H42S3O2.

Which hydrocarbon pair below have identical mass percentage of C?

When the following equation is balanced, the coefficient of Al is __________. Al (s) + H2O (l) → Al(OH) 3 (s) + H2 (g)

When the following equation is balanced, the coefficient of H2S is __________. FeCl3 (aq) + H2S (g) → Fe2S3 (s) + HCl (aq)

A sulfur oxide is 50.0% by mass sulfur. This molecular formula could be __________.

When the following equation is balanced, the coefficient of H2SO4 is __________. H2SO4 (aq) + NaOH (aq) → Na2SO4 (aq) + H2O (l)

When the following equation is balanced, the coefficient of HNO3 is __________. HNO3 (aq) + CaCO3 (s) → Ca(NO3) 2 (aq) + CO2 (g) + H2O (l)

Propane (C3H8) reacts with oxygen in the air to produce carbon dioxide and water. In a particular experiment, 38.0 grams of carbon dioxide are produced from the reaction of 22.05 grams of propane with excess oxygen. What is the % yield in this reaction?

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO3 are produced by the reaction of 5.0 grams of O2 with 6.0 grams of S. What is the % yield of SO3 in this experiment? S (s) + O2 (g) → SO3 (g) (not balanced)

When the following equation is balanced, the coefficient of HCl is __________. CaCO3 (s) + HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)