Question 1

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 2

Calculate the mass of 3.7 moles of Br₂.

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Question 3

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. A. Using the data in the table, calculate the average atomic mass for nickel. B. Is the atomic mass for nickel in your periodic table correct? C. Regardless of your answer to part B, how else could you explain the observation that the atomic mass of nickel is less than the mass of cobalt, even though it has the higher atomic number?

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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 yield of this reaction is 75%, what mass of aluminum metal can be produced from the reaction of 1.65 * 10⁶ of aluminum oxide with 1.50 * 10⁶ g of carbon?

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Question 5

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 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 6

Which of the following statements are true about a sample of sulfur and a sample of oxygen if the two samples are of equal mass?
I. The number of electrons in the two samples is about the same.
II. The number of protons in the two samples is about the same.
III. The number of atoms in the two samples is about the same.
IV. There are roughly twice as many sulfur atoms as oxygen atoms.
V. There are roughly twice as many oxygen atoms as sulfur atoms.

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Question 7

Calculate the molecular mass, in g/mol, of C₆H₁₂O₆.

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Question 8

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

First, we need to determine the mass of hexane in 10.0 mL:

mass = volume x density = 10.0 mL x 0.660 g/mL = 6.60 g

The balanced chemical equation for the combustion of hexane is:

2C6H14 + 19O2 → 12CO2 + 14H2O

From this equation, we can see that 2 moles of hexane react with 19 moles of oxygen. Find the number of moles of hexane we have:

moles of hexane = mass / molar mass = 6.60 g / 86.18 g/mol = 0.0765 mol

Now, we can use stoichiometry to find the number of moles of oxygen required:

moles of oxygen = (19/2) x moles of hexane = (19/2) x 0.0765 mol = 0.729 mol

Finally, we can convert moles of oxygen to mass:

mass of oxygen = moles of oxygen x molar mass = 0.729 mol x 32.00 g/mol = 23.3 g

Therefore, the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane is 23.3 g. Answer choice C is correct.

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 solve the problem, we need to use stoichiometry and the concept of yield. The balanced chemical equation is:

Cu2S + O2 → 2Cu + SO2

From the equation, we can see that 1 mol of Cu2S produces 2 mol of Cu. We can use this ratio to convert the desired amount of Cu (1.0 x 10^3 kg) to the amount of Cu2S needed:

1.0 x 10^3 kg Cu × (1 mol Cu / 63.55 g Cu) × (1 mol Cu2S / 2 mol Cu) × (159.16 g Cu2S / 1 mol Cu2S) = 1255.5 kg Cu2S

However, this is the amount of Cu2S that would be needed if the reaction had a 100% yield. Since the given yield is only 87%, we need to adjust the amount accordingly:

actual amount of Cu2S = theoretical amount of Cu2S / yield = 1255.5 kg / 0.87 = 1442.5 kg

Finally, we need to take into account the fact that the ore is only 46% Cu2S by mass:

mass of ore needed = actual amount of Cu2S / % Cu2S in ore = 1442.5 kg / 0.46 = 3130.4 kg

Therefore, the answer is B) 3.2 x 10^3 kg.

Question 10

Solid sodium hydrogen carbonate (also known as sodium bicarbonate)can be decomposed to form solid sodium carbonate, gaseous carbon dioxide, and water vapor. When the balanced chemical reaction for this process is written such that the coefficient of water is 1, what is the coefficient of carbon dioxide?

Accepted Answer

The balanced chemical equation is:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
The coefficient of water is already 1, so we just need to determine the coefficient of carbon dioxide. This can be found by looking at the number of carbon dioxide molecules on each side of the equation. On the left side, there is one carbon dioxide molecule, while on the right side, there is also one carbon dioxide molecule. Therefore, the coefficient of carbon dioxide is 1.

Question 11

Calculate the molecular mass, in g/mol, of P₄O₁₀.

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Question 12

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 25.5 mL of liquid heptane:

mass = volume x density = 25.5 mL x 0.6838 g/mL = 17.473 g

According to the balanced equation, the stoichiometric ratio between heptane and oxygen is:

1 mol heptane : 11 mol oxygen

Therefore, we need to find the number of moles of heptane and multiply it by 11 to get the number of moles of oxygen required.

moles of heptane = 17.473 g / 100.21 g/mol = 0.1741 mol

moles of oxygen = 0.1741 mol x 11 = 1.915 mol

Finally, we can calculate the mass of oxygen required:

mass of oxygen = moles of oxygen x molar mass of oxygen = 1.915 mol x 32.00 g/mol = 61.3 g

Therefore, the answer is choice C, 61.3 g.

Question 13

How many ICl₃ molecules are present in 1.75 kg of ICl₃?

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Question 14

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

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Question 15

Calculate the molecular mass, in g/mol, of H₂SO₄.

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Question 16

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)

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Question 17

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?

Accepted Answer

First, we need to balance the chemical equation:

2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

According to the balanced equation, 2 moles of octane are needed to react with 25 moles of oxygen to produce 16 moles of carbon dioxide. Therefore, the moles of octane and oxygen given in the problem are in a 1:1 ratio, which means only 7.5 grams of oxygen are needed to burn 15.0 grams of octane completely.

Next, we can use stoichiometry to calculate the mass of carbon dioxide produced:

- 2 moles of octane produce 16 moles of CO2 (from the balanced equation)
- 1 mole of octane has a mass of 114.23 g (molar mass of octane)
- 15.0 g of octane is equivalent to 0.131 moles of octane (since 15.0 g / 114.23 g/mol = 0.131 mol)
- Therefore, 0.131 mol of octane produces 1.05 mol of CO2 (since 0.131 mol x (16 mol CO2 / 2 mol octane) = 1.05 mol CO2)
- The molar mass of CO2 is 44.01 g/mol, so 1.05 moles of CO2 has a mass of 46.21 g (since 1.05 mol x 44.01 g/mol = 46.21 g)
- Since the yield of products is 93%, we multiply the calculated mass of CO2 by 0.93 to find the actual mass produced:

46.21 g x 0.93 = 42.98 g ≈ 12 g

Therefore, the mass of carbon dioxide produced when 15.0 g of octane is burned with 15.0 g of oxygen gas is approximately 12 grams, giving answer choice B.

Question 18

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

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Question 19

How many Mg atoms are present in 170 g of Mg?

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Question 20

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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Quiz 3: Stoichiometry

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 mass of 3.7 moles of Br₂.

Calculate the molecular mass, in g/mol, of C₆H₁₂O₆.

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)

Calculate the molecular mass, in g/mol, of P₄O₁₀.

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)

How many ICl₃ molecules are present in 1.75 kg of ICl₃?

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

Calculate the molecular mass, in g/mol, of H₂SO₄.

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)

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?

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

How many Mg atoms are present in 170 g of Mg?

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?

Quiz 3: Stoichiometry

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 mass of 3.7 moles of Br2.

Calculate the molecular mass, in g/mol, of C6H12O6.

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)

Calculate the molecular mass, in g/mol, of P4O10.

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)

How many ICl3 molecules are present in 1.75 kg of ICl3?

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

Calculate the molecular mass, in g/mol, of H2SO4.

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)

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?

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

How many Mg atoms are present in 170 g of Mg?

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?

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 mass of 3.7 moles of Br₂.

Calculate the molecular mass, in g/mol, of C₆H₁₂O₆.

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)

Calculate the molecular mass, in g/mol, of P₄O₁₀.

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)

How many ICl₃ molecules are present in 1.75 kg of ICl₃?

Calculate the molecular mass, in g/mol, of H₂SO₄.

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)

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?