Question 1

Washing soda is a hydrate of sodium carbonate. Elemental analysis of a sample of washing soda gave 4.20% C and 7.05% H. What is the formula for washing soda

Accepted Answer

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Question 2

Nickel has a lower atomic mass than cobalt, even though it has a higher atomic number. One possible explanation is that one of the average atomic masses was miscalculated. In the case of cobalt, there is only one isotope: 100% ⁵⁹Co at a mass of 58.9332 amu. For nickel, however, there are five isotopes as given in the table. $\begin{array}{|l|l|l|} \hline \text { Isotope } & \text { mass }(\mathrm{amu}) & \text { abundance } \ \hline{ }^{58} \mathrm{Ni} & 57.9354 & 67.76 \% \ \hline{ }^{60} \mathrm{Ni} & 59.9308 & 26.16 \% \ \hline{ }^{61} \mathrm{Ni} & 60.9311 & 1.25 \% \ \hline{ }^{62} \mathrm{Ni} & 61.9283 & 3.66 \% \ \hline{ }^{64} \mathrm{Ni} & 63.9280 & 1.16 \% \ \hline \end{array}$ Using the data in the table, what is the average atomic mass for nickel

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Question 3

The reaction of 60.0 g of aluminum oxide with 30.0 g of carbon produced 22.5 g of aluminum. What is the percent yield for this reaction Al₂O₃ + 3C $\rarr$ 2Al + 3CO

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Question 4

The Hall process for the production of aluminum involves the reaction of aluminum oxide with elemental carbon to give aluminum metal and carbon monoxide. If the percent yield of this reaction is 82% and aluminum ore is 71% by mass aluminum oxide, what mass of aluminum ore must be mined in order to produce 1.0 * 10³ kg (1 metric ton) of aluminum metal by the Hall process

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Question 5

A 0.8715 g sample of sorbic acid, a compound first obtained from the berries of a certain ash tree, is burned completely in oxygen to give 2.053 g of carbon dioxide and 0.5601 g of water. The empirical formula of sorbic acid is

Accepted Answer

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Question 6

The first step in the Ostwald process for producing nitric acid is 4NH₃(g) + 5O₂(g) $\rarr$ 4NO(g) + 6H₂O(g).If the reaction of 150. g of ammonia with 150. g of oxygen gas yields 87. g of nitric oxide (NO), what is the percent yield of this reaction

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Question 7

How many moles of iron are present in an iron cylinder that weighs 25 g

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Question 8

Aluminum hydroxide reacts with nitric acid to form aluminum nitrate and water. What mass of water can be formed by the reaction of 15.0 g of aluminum hydroxide with excess nitric acid

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Question 9

A method for producing pure copper metal involves the reaction of copper(I) sulfide with oxygen gas to give copper metal and sulfur dioxide. Suppose the yield of this reaction is 87%. What mass of a copper ore consisting of 46% copper(I) sulfide must be mined in order to produce 1.0 *10³ kg (1.0 metric ton) of copper metal

Accepted Answer

To produce 1.0 * 10^3 kg of copper with an 87% yield, more copper must be produced theoretically: 1.0 * 10^3 kg / 0.87 = 1.149 * 10^3 kg. The molar mass of Cu2S is 159.16 g/mol, and Cu is 63.55 g/mol. From Cu2S, 2 moles of Cu are produced, so 159.16 g of Cu2S produces 127.1 g of Cu. Therefore, 1.149 * 10^3 kg of Cu requires (1.149 * 10^3 kg * 159.16 g/mol) / 127.1 g/mol = 1.438 * 10^3 kg of Cu2S. Since the ore is 46% Cu2S, the mass of ore needed is 1.438 * 10^3 kg / 0.46 = 3.126 * 10^3 kg, approximately 3.2 * 10^3 kg.

Question 10

A 1.375 g sample of mannitol, a sugar found in seaweed, is burned completely in oxygen to give 1.993 g of carbon dioxide and 0.9519 g of water. The empirical formula of mannitol is

Accepted Answer

To find the empirical formula, calculate the moles of carbon, hydrogen, and oxygen in the products. From 1.993 g of CO2, there are 0.0453 moles of C. From 0.9519 g of H2O, there are 0.1056 moles of H. The remaining mass is oxygen, which is 1.375 g - (mass of C + mass of H), giving 0.0228 moles of O. The simplest ratio of C:H:O is 3:7:3, corresponding to the empirical formula C3H7O3.

Question 11

When octane (C₈H₁₈) is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas

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Question 12

Liquid heptane, C₇H₁₆ , burns in oxygen gas to yield carbon dioxide and water. What mass of carbon dioxide is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

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Question 13

Calculate the molar mass, in g/mol, of Al₂(SO₄)₃.

Accepted Answer

To calculate the molar mass of the compound, we need to add up the atomic masses of all its constituent elements. The atomic masses of Al, S, U, and B can be found on the periodic table:

Al: 26.98 g/mol 
S: 32.06 g/mol 
U: 238.03 g/mol 
B: 10.81 g/mol

We see that the compound contains 1 Al, 2 S, 2 U, and 27 B atoms. It also contains 15 oxygen atoms, which can be calculated as follows: 
14 from (SO4)2-, 1 from SO4-

Thus, the total molar mass of the compound can be calculated as: 
(1 * 26.98 g/mol) + (2 * 32.06 g/mol) + (2 * 238.03 g/mol) + (27 * 10.81 g/mol) + (15 * 15.99 g/mol)

= 342.17 g/mol

Therefore, the answer is C.

Question 14

One way of obtaining pure sodium carbonate is through the decomposition of the mineral trona, Na ₃(CO₃)(HCO₃)$\times$2H₂O, as shown in the following reaction: 2Na₃(CO₃)(HCO₃)$\rarr$2H₂O(s) $\rarr$3Na₂CO₃(s) + CO₂(g) + 5H₂O(g) When 15 metric tons (1 * 10³ kg) of trona is decomposed, 11 metric tons of Na₂CO₃ is recovered. What is the percent yield of this reaction? (1 metric ton = 10³ kg)

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Question 15

How many moles of aluminum are present in an Al cylinder with a mass of 15 g

Accepted Answer

The molar mass of aluminum is 26.98 g/mol.

We can use the formula:

moles = mass / molar mass

moles = 15 g / 26.98 g/mol = 0.556 moles

Therefore, the answer is choice C.

Question 16

The Hall process for the production of aluminum involves the reaction of aluminum oxide with elemental carbon to give aluminum metal and carbon monoxide. If the yield of this reaction is 75%, what mass of aluminum metal can be produced from the reaction of 1.65 * 10⁶ g of aluminum oxide with 1.50 * 10⁶ g of carbon

Accepted Answer

The balanced equation for the Hall process is: 2 Al2O3 + 3 C → 4 Al + 3 CO. First, calculate the moles of Al2O3: (1.65 * 10^6 g) / (101.96 g/mol) = 16189.5 mol. From the stoichiometry, 2 moles of Al2O3 produce 4 moles of Al, so 16189.5 mol of Al2O3 produce 32379 mol of Al. Convert moles of Al to grams: 32379 mol * 26.98 g/mol = 873,000 g. Considering the 75% yield: 873,000 g * 0.75 = 654,750 g, which is approximately 6.6 * 10^5 g.

Question 17

Liquid hexane, C₆H₁₄, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane (density of hexane = 0.660 g/mL)

Accepted Answer

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Question 18

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Accepted Answer

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Question 19

Calculate the molar mass, in g/mol, of Fe₂(CO₃)₃.

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Question 20

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 25.5 mL of heptane (density of heptane = 0.6838 g/mL)

Accepted Answer

First, we need to calculate the mass of heptane using its density:
Density of heptane = 0.6838 g/mL
Volume of heptane = 25.5 mL
Mass of heptane = density x volume = 0.6838 g/mL x 25.5 mL = 17.4465 g

Next, we need to balance the chemical equation:
C7H16 + 11O2 → 7CO2 + 8H2O

From the balanced equation, we can see that for every 1 mol of heptane, we need 11 mol of oxygen gas. The molar mass of heptane is 100.205 g/mol (7 x 12.01 g/mol + 16 x 1.01 g/mol), so the number of moles of heptane in 17.4465 g is:
n = mass / molar mass = 17.4465 g / 100.205 g/mol = 0.1741 mol

Therefore, the minimum mass of oxygen required is:
Mass of oxygen = n x 11 x molar mass of oxygen = 0.1741 mol x 11 x 32 g/mol = 61.3072 g

Rounding to the appropriate number of significant figures gives the final answer of 61.3 g of oxygen.

Quiz 3: Mass Relationships in Chemical Reactions

Washing soda is a hydrate of sodium carbonate. Elemental analysis of a sample of washing soda gave 4.20% C and 7.05% H. What is the formula for washing soda

The reaction of 60.0 g of aluminum oxide with 30.0 g of carbon produced 22.5 g of aluminum. What is the percent yield for this reaction Al₂O₃ + 3C $\rarr$ 2Al + 3CO

A 0.8715 g sample of sorbic acid, a compound first obtained from the berries of a certain ash tree, is burned completely in oxygen to give 2.053 g of carbon dioxide and 0.5601 g of water. The empirical formula of sorbic acid is

The first step in the Ostwald process for producing nitric acid is 4NH₃(g) + 5O₂(g) $\rarr$ 4NO(g) + 6H₂O(g) .If the reaction of 150. g of ammonia with 150. g of oxygen gas yields 87. g of nitric oxide (NO) , what is the percent yield of this reaction

How many moles of iron are present in an iron cylinder that weighs 25 g

Aluminum hydroxide reacts with nitric acid to form aluminum nitrate and water. What mass of water can be formed by the reaction of 15.0 g of aluminum hydroxide with excess nitric acid

A 1.375 g sample of mannitol, a sugar found in seaweed, is burned completely in oxygen to give 1.993 g of carbon dioxide and 0.9519 g of water. The empirical formula of mannitol is

When octane (C₈H₁₈) is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas

Liquid heptane, C₇H₁₆ , burns in oxygen gas to yield carbon dioxide and water. What mass of carbon dioxide is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Calculate the molar mass, in g/mol, of Al₂(SO₄) ₃.

How many moles of aluminum are present in an Al cylinder with a mass of 15 g

Liquid hexane, C₆H₁₄, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane (density of hexane = 0.660 g/mL)

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Calculate the molar mass, in g/mol, of Fe₂(CO₃) ₃.

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 25.5 mL of heptane (density of heptane = 0.6838 g/mL)

Quiz 3: Mass Relationships in Chemical Reactions

Washing soda is a hydrate of sodium carbonate. Elemental analysis of a sample of washing soda gave 4.20% C and 7.05% H. What is the formula for washing soda

The reaction of 60.0 g of aluminum oxide with 30.0 g of carbon produced 22.5 g of aluminum. What is the percent yield for this reaction Al2O3 + 3C →\rarr→ 2Al + 3CO

A 0.8715 g sample of sorbic acid, a compound first obtained from the berries of a certain ash tree, is burned completely in oxygen to give 2.053 g of carbon dioxide and 0.5601 g of water. The empirical formula of sorbic acid is

The first step in the Ostwald process for producing nitric acid is 4NH3(g) + 5O2(g) →\rarr→ 4NO(g) + 6H2O(g) .If the reaction of 150. g of ammonia with 150. g of oxygen gas yields 87. g of nitric oxide (NO) , what is the percent yield of this reaction

How many moles of iron are present in an iron cylinder that weighs 25 g

Aluminum hydroxide reacts with nitric acid to form aluminum nitrate and water. What mass of water can be formed by the reaction of 15.0 g of aluminum hydroxide with excess nitric acid

A 1.375 g sample of mannitol, a sugar found in seaweed, is burned completely in oxygen to give 1.993 g of carbon dioxide and 0.9519 g of water. The empirical formula of mannitol is

When octane (C8H18) is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas

Liquid heptane, C7H16 , burns in oxygen gas to yield carbon dioxide and water. What mass of carbon dioxide is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Calculate the molar mass, in g/mol, of Al2(SO4) 3.

How many moles of aluminum are present in an Al cylinder with a mass of 15 g

Liquid hexane, C6H14, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane (density of hexane = 0.660 g/mL)

Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Calculate the molar mass, in g/mol, of Fe2(CO3) 3.

Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 25.5 mL of heptane (density of heptane = 0.6838 g/mL)

The reaction of 60.0 g of aluminum oxide with 30.0 g of carbon produced 22.5 g of aluminum. What is the percent yield for this reaction Al₂O₃ + 3C $\rarr$ 2Al + 3CO

The first step in the Ostwald process for producing nitric acid is 4NH₃(g) + 5O₂(g) $\rarr$ 4NO(g) + 6H₂O(g) .If the reaction of 150. g of ammonia with 150. g of oxygen gas yields 87. g of nitric oxide (NO) , what is the percent yield of this reaction

When octane (C₈H₁₈) is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas

Liquid heptane, C₇H₁₆ , burns in oxygen gas to yield carbon dioxide and water. What mass of carbon dioxide is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Calculate the molar mass, in g/mol, of Al₂(SO₄) ₃.

Liquid hexane, C₆H₁₄, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane (density of hexane = 0.660 g/mL)

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What mass of water is produced when 15.0 mL of heptane burns completely (density of heptane = 0.6838 g/mL)

Calculate the molar mass, in g/mol, of Fe₂(CO₃) ₃.

Liquid heptane, C₇H₁₆, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 25.5 mL of heptane (density of heptane = 0.6838 g/mL)