Question 1

Consider the following reaction: 4NH₃(g) + 7O₂(g) $\rightarrow$4NO₂(g) + 6H₂O(l) Consider an experiment in which you react ammonia and oxygen. At the end of the experiment, you find that you produced 27.0 g of water, and 8.52 g of ammonia is left over. Calculate the initial mass of ammonia. Assume the reaction went to completion.

Accepted Answer

The balanced chemical equation for the reaction between ammonia and oxygen is:

4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

From the balanced equation, we can see that 4 moles of ammonia react with 5 moles of oxygen to produce 6 moles of water. Therefore, the theoretical yield of water from the given 8.52 g of ammonia is:

(6/4) x (8.52 g / 17.03 g/mol) x ( 18.02 g/mol) = 27.0 g

where 17.03 g/mol and 18.02 g/mol are the molar masses of NH3 and H2O respectively.

This means that all the ammonia has reacted to give the observed 27.0 g of water. Therefore, the initial mass of ammonia which reacted with oxygen is:

8.52 g

However, the question asks for the initial mass of ammonia before the reaction. To get that, we need to add the mass of ammonia which did not react:

Initial mass of ammonia = 8.52 g + mass of unreacted NH3

The mass of unreacted NH3 can be calculated by subtracting the mass of NH3 which reacted from the initial mass of NH3:

Initial mass of ammonia = 8.52 g + (mass of NH3 which did not react)

Initial mass of ammonia = 8.52 g + [(initial mass of NH3 - final mass of NH3)]

We don't know the final mass of NH3, but we know that all of the ammonia did not react. Therefore:

final mass of NH3 = 0 g

Substituting this value in the equation above, we get:

Initial mass of ammonia = 8.52 g + [(initial mass of NH3 - 0 g)]

Initial mass of ammonia = 8.52 g + initial mass of NH3

Initial mass of ammonia = 8.52 g + x (say)

Now, we know that the theoretical yield of water from the given mass of ammonia is the same as the observed yield of water. Therefore:

(6/4) x (8.52 g / 17.03 g/mol) x ( 18.02 g/mol) = x + 8.52 g

Solving for x, we get:

x = 25.5 g

Therefore, the initial mass of ammonia was 25.5 g.

Question 2

When 10.0 g of hydrogen gas reacts with 10.0 g of oxygen gas to form water, what is the theoretical yield of water?

Accepted Answer

The balanced equation for the reaction is:

2 H2 + O2 → 2 H2O

From this equation, we can see that 2 moles of H2 react with 1 mole of O2 to form 2 moles of H2O. To find the theoretical yield of water, we need to determine which reactant limits the reaction. This is done by calculating the moles of each reactant and then comparing them.

Moles of H2 = (10.0 g)/(2.016 g/mol) = 4.97 mol
Moles of O2 = (10.0 g)/(32.00 g/mol) = 0.3125 mol

Since the moles of O2 are less than half of the moles of H2, we can conclude that O2 is the limiting reactant. Therefore, we need to use the amount of O2 to calculate the theoretical yield of water.

From the balanced equation, we can see that 1 mole of O2 reacts to form 2 moles of H2O. Therefore, the moles of H2O formed from 0.3125 moles of O2 is:

Moles of H2O = (0.3125 mol O2) x (2 mol H2O/1 mol O2) = 0.625 mol H2O

The mass of 0.625 moles of H2O is:

Mass of H2O = (0.625 mol) x (18.015 g/mol) = 11.3 g

Therefore, the theoretical yield of water is 11.3 g, which is answer choice C.

Question 3

Sodium perbromate can be synthesized via the following reaction that gives off xenon gas. __NaBrO₃ + __XeF₂ + __H₂O __NaBrO₄ + HF + __Xe What stoichiomatric coefficients should be placed in the blanks above to balance the chemical equation?

Accepted Answer

The answer of Sodium perbromate can be synthesized via the...

Question 4

The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of 2.78 g of ethyl butyrate leads to formation of 6.32 g of CO₂ and 2.58 g of H₂O. The properties of the compound suggest that the molar mass should be between 100 and 150. What is the molecular formula?

Accepted Answer

The answer of The characteristic odor of pineapple is due...

Question 5

Hemoglobin is the protein that transports oxygen in mammals. Hemoglobin is 0.342% Fe by mass, and each hemoglobin molecule contains four iron atoms. Calculate the molar mass of hemoglobin

Accepted Answer

The answer of Hemoglobin is the protein that transports oxygen...

Question 6

Consider the electrolysis of a brine solution: 2NaCl(aq) + H₂O$\rightarrow$ Cl₂(g) + H₂(g) + 2NaOH(aq) A 10.0-g sample of sodium chloride was placed in 10.0 g of water. If 3.85 g of Cl₂ was obtained, what was the percent yield of Cl₂?

Accepted Answer

The theoretical yield of Cl₂ can be calculated from the moles of NaCl, which is the limiting reactant. The molar mass of NaCl is 58.44 g/mol, so 10.0 g of NaCl is 0.171 mol. According to the balanced equation, 1 mol of NaCl produces 0.5 mol of Cl₂. Therefore, 0.171 mol of NaCl produces 0.0855 mol of Cl₂. The molar mass of Cl₂ is 70.90 g/mol, so the theoretical yield is 0.0855 mol × 70.90 g/mol = 6.06 g. The percent yield is (3.85 g / 6.06 g) × 100% = 63.5%.

Question 7

Triphenylene is an organic compound containing only carbon and hydrogen with the empirical formula C₃H₂. Which of the following is a possible molecular mass for triphenylene?

Accepted Answer

To find the molecular mass of triphenylene, we need to determine its molecular formula. From the empirical formula, we can determine that the molecule contains 14 carbon atoms (C14) and 12 hydrogen atoms (H12). We can then use the remaining atoms (two sulfur and two boron) to determine the additional formula units of triphenylene. Looking at the answer choices, only choice C (228.3 g/mol) matches a possible molecular formula for triphenylene, which is C18H12S2B2. This gives a molecular mass of (14 x 12.011) + (12 x 1.008) + (2 x 32.06) + (2 x 10.81) = 228.324 g/mol. Therefore, the answer is C.

Question 8

Consider the following balanced equation: A(g) + 5B(g) $\rightarrow$3C + 4D
When equal masses of A and B are reacted, which is limiting?

Accepted Answer

The answer of Consider the following balanced equation: A(g) +...

Question 9

In the reaction 2A + B $\rightarrow$ 3C + D
3)0 mol A and 2.0 mol B react to form 4.0 mol C. What is the percent yield of this reaction?

Accepted Answer

Based on the stoichiometry of the reaction, 2 mol of B should react with 2/3 mol of A to produce 4/3 mol of C. However, since there is no A present, only the amount of C that can be produced from the 2 mol of B is 4.0 mol. Therefore, the actual yield is 4.0 mol and the theoretical yield is 4/3 mol. The percent yield is calculated by (actual yield/theoretical yield) x 100%, which gives (4.0 mol / (4/3) mol) x 100% = 89%. Therefore, the best choice is B.

Question 10

Indium has two naturally occurring isotopes with masses given in the table below. The relative atomic mass given for antimony on the periodic table is 114.82.  When a natural sample of indium is placed in a mass spectrometer, which of the following will be true?

Accepted Answer

The answer of Indium has two naturally occurring isotopes with...

Question 11

Sodium perbromate can be synthesized via the following reaction that gives off Xenon gas. NaBrO₃ + XeF₂ + H₂O NaBrO₄ + 2HF + Xe A reaction is started with 200.0g of NaBrO₃, 200.0g of XeF₂ and 100.0g of water. Assuming that the reaction goes to completion, and that all of the formed xenon gas is allowed to escape into the atmosphere, what will be the minimum mass of products and reactants remaining in the reaction vessel?

Accepted Answer

The answer of Sodium perbromate can be synthesized via the...

Question 12

A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride: 2Li + F₂ $\rightarrow$ 2LiF. After the reaction is complete, what will be present?

Accepted Answer

The answer of A 15-g sample of lithium is reacted...

Question 13

Acetylsalicylic acid, or aspirin (CS1U1B19S1U1B0HS1U1B18S1U1B0OS1U1B14S1U1B0), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid.
-Determine the number of moles of acetylsalicylic acid per tablet.

Accepted Answer

The answer of Acetylsalicylic acid, or aspirin (CS1U1B19S1U1B0HS1U1B18S1U1B0OS1U1B14S1U1B0), is an...

Question 14

Consider the following two unbalanced equations. CH₄ + O₂ $\rightarrow$CO₂ + H₂O H₂ + O₂ $\rightarrow$H₂O Suppose you carry out each reaction with the same mass of oxygen (and with an excess of CH₄ and H₂). In which case will you make more water, and by what factor?

Accepted Answer

The answer of Consider the following two unbalanced equations. CH₄ +...

Question 15

Acetylsalicylic acid, or aspirin (CS1U1B19S1U1B0HS1U1B18S1U1B0OS1U1B14S1U1B0), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid.
-Determine the number of molecules of acetylsalicylic acid in the tablet.

Accepted Answer

The answer of Acetylsalicylic acid, or aspirin (CS1U1B19S1U1B0HS1U1B18S1U1B0OS1U1B14S1U1B0), is an...

Question 16

Consider a reaction in which two reactants make one product (for example, consider the unbalanced A + B  C). You know the following:
2)0 mol A (with an excess of B) can make a maximum of 2.0 mol C
3)0 mol B (with an excess of A) can make a maximum of 4.0 mol C
If you react 2.0 mol A and 3.0 mol B, what is the maximum amount of C that can be produced?

Accepted Answer

The answer of Consider a reaction in which two reactants...

Question 17

A 100.0-g mixture of methane (CH₄) and propane (C₃H₈) reacts with oxygen to make carbon dioxide and water. The carbon dioxide produced has a mass of 231.25 g. Determine the percent by mass of methane in the mixture.

Accepted Answer

The answer of A 100.0-g mixture of methane (CH₄) and...

Question 18

SO₂ reacts with H₂S as follows: 2H₂S + SO₂ $\rightarrow$ 3S + 2H₂O When 7.50 g of H₂S reacts with 12.75 g of SO₂, which statement applies?

Accepted Answer

To determine the limiting reactant, we need to calculate the number of moles of each reactant: moles of H₂S = 7.50 g / (32 g/mol + 2(32 g/mol) + 32 g/mol + 32 g/mol + 32 g/mol) = 0.0216 mol moles of SO₂ = 12.75 g / (32 g/mol + 2(32 g/mol) + 32 g/mol + 32 g/mol + 32 g/mol) = 0.0366 mol We see that there are fewer moles of H₂S, so it is the limiting reactant. Using the balanced equation, we can calculate the amount of sulfur produced: 2 mol H₂S produces 3 mol S 0.0216 mol H₂S produces (3/2)(0.0216) mol S = 0.0324 mol S We can convert mol S to grams: 0.0324 mol S x 32.07 g/mol = 1.04 g S Therefore, the answer is D, 10.6 g of sulfur is formed.

Question 19

Acetylsalicylic acid, or aspirin (CS1U1B19S1U1B0HS1U1B18S1U1B0OS1U1B14S1U1B0), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid.
-Determine the molar mass of acetylsalicylic acid.

Accepted Answer

The answer of Acetylsalicylic acid, or aspirin (CS1U1B19S1U1B0HS1U1B18S1U1B0OS1U1B14S1U1B0), is an...

Question 20

Consider the following reaction: CH₄(g) + 4Cl₂(g) $\rightarrow$ CCl₄(g) + 4HCl(g) What mass of CCl₄ will be formed if 1.6 moles of methane react with 1.6 moles of chlorine?

Accepted Answer

The balanced equation for the reaction shows that 1 mole of CH₄ reacts with 4 moles of Cl₂ to produce 1 mole of CCl₄ and 4 moles of HCl. Therefore, if 1.6 moles of methane react with 1.6 moles of chlorine, the limiting reagent is methane, which will be completely consumed. The reaction will produce 1.6 mol / 1 mol CH₄ x 1 mol CCl₄ / 1 mol CH₄ = 1.6 mol CCl₄. To convert moles of CCl₄ to grams, we need to use its molar mass. The molar mass of CCl₄ is 154 g/mol (12.01 + 4 x 1.01 + 14.01 + 4 x 35.45). Therefore, the mass of CCl₄ produced is 1.6 mol x 154 g/mol = 246.4 g. Rounding off to two significant figures gives the answer of 61.5 g, which is choice D.

Quiz 3: Stoichiometry

When 10.0 g of hydrogen gas reacts with 10.0 g of oxygen gas to form water, what is the theoretical yield of water?

Sodium perbromate can be synthesized via the following reaction that gives off xenon gas. NaBrO₃ + XeF₂ + H₂O NaBrO₄ + HF + __Xe What stoichiomatric coefficients should be placed in the blanks above to balance the chemical equation?

Hemoglobin is the protein that transports oxygen in mammals. Hemoglobin is 0.342% Fe by mass, and each hemoglobin molecule contains four iron atoms. Calculate the molar mass of hemoglobin

Consider the electrolysis of a brine solution: 2NaCl(aq) + H₂O $\rightarrow$ Cl₂(g) + H₂(g) + 2NaOH(aq) A 10.0-g sample of sodium chloride was placed in 10.0 g of water. If 3.85 g of Cl₂ was obtained, what was the percent yield of Cl₂?

Triphenylene is an organic compound containing only carbon and hydrogen with the empirical formula C₃H₂. Which of the following is a possible molecular mass for triphenylene?

Consider the following balanced equation: A(g) + 5B(g) $\rightarrow$ 3C + 4D When equal masses of A and B are reacted, which is limiting?

In the reaction 2A + B $\rightarrow$ 3C + D 3) 0 mol A and 2.0 mol B react to form 4.0 mol C. What is the percent yield of this reaction?

Indium has two naturally occurring isotopes with masses given in the table below. The relative atomic mass given for antimony on the periodic table is 114.82. When a natural sample of indium is placed in a mass spectrometer, which of the following will be true?

A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride: 2Li + F₂ $\rightarrow$ 2LiF. After the reaction is complete, what will be present?

Acetylsalicylic acid, or aspirin (C₉H₈O₄), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the number of moles of acetylsalicylic acid per tablet.

Consider the following two unbalanced equations. CH₄ + O₂ $\rightarrow$ CO₂ + H₂O H₂ + O₂ $\rightarrow$ H₂O Suppose you carry out each reaction with the same mass of oxygen (and with an excess of CH₄ and H₂). In which case will you make more water, and by what factor?

Acetylsalicylic acid, or aspirin (C₉H₈O₄), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the number of molecules of acetylsalicylic acid in the tablet.

A 100.0-g mixture of methane (CH₄) and propane (C₃H₈) reacts with oxygen to make carbon dioxide and water. The carbon dioxide produced has a mass of 231.25 g. Determine the percent by mass of methane in the mixture.

SO₂ reacts with H₂S as follows: 2H₂S + SO₂ $\rightarrow$ 3S + 2H₂O When 7.50 g of H₂S reacts with 12.75 g of SO₂, which statement applies?

Acetylsalicylic acid, or aspirin (C₉H₈O₄), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the molar mass of acetylsalicylic acid.

Consider the following reaction: CH₄(g) + 4Cl₂(g) $\rightarrow$ CCl₄(g) + 4HCl(g) What mass of CCl₄ will be formed if 1.6 moles of methane react with 1.6 moles of chlorine?

Quiz 3: Stoichiometry

When 10.0 g of hydrogen gas reacts with 10.0 g of oxygen gas to form water, what is the theoretical yield of water?

Sodium perbromate can be synthesized via the following reaction that gives off xenon gas. __NaBrO3 + __XeF2 + __H2O __NaBrO4 + HF + __Xe What stoichiomatric coefficients should be placed in the blanks above to balance the chemical equation?

Hemoglobin is the protein that transports oxygen in mammals. Hemoglobin is 0.342% Fe by mass, and each hemoglobin molecule contains four iron atoms. Calculate the molar mass of hemoglobin

Consider the electrolysis of a brine solution: 2NaCl(aq) + H2O →\rightarrow→ Cl2(g) + H2(g) + 2NaOH(aq) A 10.0-g sample of sodium chloride was placed in 10.0 g of water. If 3.85 g of Cl2 was obtained, what was the percent yield of Cl2?

Triphenylene is an organic compound containing only carbon and hydrogen with the empirical formula C3H2. Which of the following is a possible molecular mass for triphenylene?

Consider the following balanced equation: A(g) + 5B(g) →\rightarrow→ 3C + 4D When equal masses of A and B are reacted, which is limiting?

In the reaction 2A + B →\rightarrow→ 3C + D 3) 0 mol A and 2.0 mol B react to form 4.0 mol C. What is the percent yield of this reaction?

Indium has two naturally occurring isotopes with masses given in the table below. The relative atomic mass given for antimony on the periodic table is 114.82. When a natural sample of indium is placed in a mass spectrometer, which of the following will be true?

A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride: 2Li + F2 →\rightarrow→ 2LiF. After the reaction is complete, what will be present?

Acetylsalicylic acid, or aspirin (C9H8O4), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the number of moles of acetylsalicylic acid per tablet.

Consider the following two unbalanced equations. CH4 + O2 →\rightarrow→ CO2 + H2O H2 + O2 →\rightarrow→ H2O Suppose you carry out each reaction with the same mass of oxygen (and with an excess of CH4 and H2). In which case will you make more water, and by what factor?

Acetylsalicylic acid, or aspirin (C9H8O4), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the number of molecules of acetylsalicylic acid in the tablet.

A 100.0-g mixture of methane (CH4) and propane (C3H8) reacts with oxygen to make carbon dioxide and water. The carbon dioxide produced has a mass of 231.25 g. Determine the percent by mass of methane in the mixture.

SO2 reacts with H2S as follows: 2H2S + SO2 →\rightarrow→ 3S + 2H2O When 7.50 g of H2S reacts with 12.75 g of SO2, which statement applies?

Acetylsalicylic acid, or aspirin (C9H8O4), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the molar mass of acetylsalicylic acid.

Consider the following reaction: CH4(g) + 4Cl2(g) →\rightarrow→ CCl4(g) + 4HCl(g) What mass of CCl4 will be formed if 1.6 moles of methane react with 1.6 moles of chlorine?

Sodium perbromate can be synthesized via the following reaction that gives off xenon gas. NaBrO₃ + XeF₂ + H₂O NaBrO₄ + HF + __Xe What stoichiomatric coefficients should be placed in the blanks above to balance the chemical equation?

Consider the electrolysis of a brine solution: 2NaCl(aq) + H₂O $\rightarrow$ Cl₂(g) + H₂(g) + 2NaOH(aq) A 10.0-g sample of sodium chloride was placed in 10.0 g of water. If 3.85 g of Cl₂ was obtained, what was the percent yield of Cl₂?

Triphenylene is an organic compound containing only carbon and hydrogen with the empirical formula C₃H₂. Which of the following is a possible molecular mass for triphenylene?

Consider the following balanced equation: A(g) + 5B(g) $\rightarrow$ 3C + 4D When equal masses of A and B are reacted, which is limiting?

In the reaction 2A + B $\rightarrow$ 3C + D 3) 0 mol A and 2.0 mol B react to form 4.0 mol C. What is the percent yield of this reaction?

A 15-g sample of lithium is reacted with 15 g of fluorine to form lithium fluoride: 2Li + F₂ $\rightarrow$ 2LiF. After the reaction is complete, what will be present?

Acetylsalicylic acid, or aspirin (C₉H₈O₄), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the number of moles of acetylsalicylic acid per tablet.

Consider the following two unbalanced equations. CH₄ + O₂ $\rightarrow$ CO₂ + H₂O H₂ + O₂ $\rightarrow$ H₂O Suppose you carry out each reaction with the same mass of oxygen (and with an excess of CH₄ and H₂). In which case will you make more water, and by what factor?

Acetylsalicylic acid, or aspirin (C₉H₈O₄), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the number of molecules of acetylsalicylic acid in the tablet.

A 100.0-g mixture of methane (CH₄) and propane (C₃H₈) reacts with oxygen to make carbon dioxide and water. The carbon dioxide produced has a mass of 231.25 g. Determine the percent by mass of methane in the mixture.

SO₂ reacts with H₂S as follows: 2H₂S + SO₂ $\rightarrow$ 3S + 2H₂O When 7.50 g of H₂S reacts with 12.75 g of SO₂, which statement applies?

Acetylsalicylic acid, or aspirin (C₉H₈O₄), is an analgesic (pain reliever). A typical aspirin tablet contains 500.0 mg of acetylsalicylic acid. -Determine the molar mass of acetylsalicylic acid.

Consider the following reaction: CH₄(g) + 4Cl₂(g) $\rightarrow$ CCl₄(g) + 4HCl(g) What mass of CCl₄ will be formed if 1.6 moles of methane react with 1.6 moles of chlorine?