Question 1

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

The molecular formula of nitrogen oxide is either NO or NO2. However, since the given compound has 63.65% nitrogen, its molecular formula must have at least one nitrogen atom. Therefore, the molecular formula of the compound could be N2O or N2O2. Only option C, N₂O, contains both nitrogen and oxygen atoms and has the correct ratio of nitrogen to oxygen atoms for both N2O and N2O2. Option A, NO, does not have enough nitrogen atoms, and options B and D contain sulfur atoms, which are not present in nitrogen oxide. Therefore, the best choice is C.

Question 2

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

The balanced equation is Ca + 2H2O → Ca(OH)2 + H2. The coefficient of H2O is 2.

Question 3

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 4

The molecular formula of aspartame, the generic name of NutraSweet^®, is C₁₄H₁₈N₂O₅. The molar mass of aspartame, rounded to the nearest integer, is ________ g. A)24 B)156 C)294 D)43 E)39

Accepted Answer

To find the molar mass of aspartame, we need to add up the atomic masses of each element in the molecular formula. The atomic masses can be found on the periodic table. When we add up the atomic masses for each element, we get a molar mass of approximately 294 g/mol, which is closest to option C. Therefore, the correct answer is C.

Question 5

How many moles of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms? A)5.890 × 10^-7 B)2.945 × 10^-7 C)1.473 × 10^-7 D)8.836 × 10^-7 E)9.817 × 10^-⁸

Accepted Answer

Sodium carbonate (Na2CO3) contains one carbon atom per molecule. Using Avogadro's number (6.022 × 10^23 atoms/mol), the number of moles is calculated as (1.773 × 10^17 atoms) / (6.022 × 10^23 atoms/mol) = 2.945 × 10^-7 moles.

Question 6

Which hydrocarbon pair below has 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 has identical mass...

Question 7

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 8

How many sulfur dioxide molecules are there in 1.80 mol of sulfur dioxide? A)1.08 × 10²³ B)6.02 × 10²⁴ C)1.80 × 10²⁴ D)1.08 × 10²⁴ E)6.02 × 10²³

Accepted Answer

1.80 mol of sulfur dioxide contains 1.80 mol * 6.022 * 10^23 molecules = 1.08 * 10^24 molecules.

Question 9

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 equation has one nitrogen atom (N) and one sulfur atom (S) on each side. Therefore, the coefficients for NH₃ and NO₂ should be equal. - The equation has 12 hydrogen atoms (H) and 12 oxygen atoms (O) on each side. Therefore, the coefficients for H₂O and O₂ should be equal. - To achieve this, we need 4 molecules of NH₃ and 7 molecules of O₂ on the left side, and 4 molecules of NO₂ and 6 molecules of H₂O on the right side. - Therefore, the coefficients are: 4 NH₃ (g) + 7 O₂ (g) → 4 NO₂ (g) + 6 H₂O (g).

Question 10

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 11

How many carbon atoms are there in 52.06 g of carbon dioxide? A)5.206 × 10²⁴ B)3.134 × 10²⁵ C)7.122 × 10²³ D)8.648 × 10^-²³ E)1.424 × 10²⁴

Accepted Answer

The molar mass of CO2 is 44.01 g/mol. 52.06 g of CO2 is 52.06/44.01 = 1.183 moles. Each mole contains Avogadro's number of molecules (6.022 × 10^23), so 1.183 moles contain 1.183 × 6.022 × 10^23 = 7.122 × 10^23 carbon atoms.

Question 12

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.

Question 13

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 14

How many oxygen atoms are there in 52.06 g of carbon dioxide? A)1.424 × 10²⁴ B)6.022 × 10²³ C)1.204 × 10²⁴ D)5.088 × 10²³ E)1.018 × 10²⁴

Accepted Answer

The molar mass of CO2 is 44.01 g/mol. 52.06 g of CO2 is 52.06/44.01 = 1.183 moles. Each mole of CO2 contains 2 moles of oxygen atoms, so there are 2 * 1.183 = 2.366 moles of oxygen atoms. Using Avogadro's number (6.022 × 10^23 atoms/mol), the number of oxygen atoms is 2.366 * 6.022 × 10^23 = 1.424 × 10^24.

Question 15

How many grams of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms? A)3.121 × 10^-⁵ B)1.011 × 10^-⁵ C)1.517 × 10^-⁵ D)9.100 × 10^-⁵ E)6.066 × 10^-⁵

Accepted Answer

The answer of How many grams of sodium carbonate contain...

Question 16

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 17

The compound responsible for the characteristic smell of garlic is allicin, C₆H₁₀OS₂. The mass of 1.00 mol of allicin, rounded to the nearest integer, is ________ g. A)34 B)162 C)86 D)61 E)19

Accepted Answer

The molar mass of allicin (C6H10OS2) is calculated by adding the atomic masses of all the atoms: (6*12) + (10*1) + (16) + (2*32) = 162 g/mol.

Question 18

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 19

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

Accepted Answer

The answer of There are ________ oxygen atoms in 30...

Question 20

How many sulfur dioxide molecules are there in 0.180 mol of sulfur dioxide? A)1.80 × 10²³ B)6.02 × 10²⁴ C)6.02 × 10²³ D)1.08 × 10²⁴ E)1.08 × 10²³

Accepted Answer

The answer of How many sulfur dioxide molecules are there...

Quiz 3: Stoichiometry: Calculations With Chemical Formulas and Equations

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

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 coefficient of Al is ________. Al (s) + H₂O (l) → Al(OH) ₃ (s) + H₂ (g)

The molecular formula of aspartame, the generic name of NutraSweet^®, is C₁₄H₁₈N₂O₅. The molar mass of aspartame, rounded to the nearest integer, is ________ g.

How many moles of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms?

Which hydrocarbon pair below has identical mass percentage of C?

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

How many sulfur dioxide molecules are there in 1.80 mol of sulfur dioxide?

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 H₂S is ________. FeCl₃ (aq) + H₂S (g) → Fe₂S₃ (s) + HCl (aq)

How many carbon atoms are there in 52.06 g of carbon dioxide?

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

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

How many oxygen atoms are there in 52.06 g of carbon dioxide?

How many grams of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms?

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

The compound responsible for the characteristic smell of garlic is allicin, C₆H₁₀OS₂. The mass of 1.00 mol of allicin, rounded to the nearest integer, is ________ g.

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?

There are ________ oxygen atoms in 30 molecules of C₂₀H₄₂S₃O₂.

How many sulfur dioxide molecules are there in 0.180 mol of sulfur dioxide?

Quiz 3: Stoichiometry: Calculations With Chemical Formulas and Equations

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

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 coefficient of Al is ________. Al (s) + H2O (l) → Al(OH) 3 (s) + H2 (g)

The molecular formula of aspartame, the generic name of NutraSweet®, is C14H18N2O5. The molar mass of aspartame, rounded to the nearest integer, is ________ g.

How many moles of sodium carbonate contain 1.773 × 1017 carbon atoms?

Which hydrocarbon pair below has identical mass percentage of C?

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

How many sulfur dioxide molecules are there in 1.80 mol of sulfur dioxide?

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 H2S is ________. FeCl3 (aq) + H2S (g) → Fe2S3 (s) + HCl (aq)