Question 1

​A sample of dysprosium (atomic mass 162.5 u)  contains 8 atoms. Determine the mass of the sample.

Accepted Answer

A)   2.16 × 10−21 g
B)   1.08 × 10−21 g
C)   ​0.88 × 10−21 g
D)   3.65 × 10−21 g
E)   4.11 × 10−21 g

Question 2

What is the subscript of aluminum in the formula of aluminum phosphate?

Accepted Answer

A)   3
B)   1
C)   2
D)   0
E)   4

Question 3

Consider the following reaction:
CH4(g)  + 4Cl2(g)  → CCl4(g)  + 4HCl(g) 
What mass of CCl4 is formed by the reaction of 8.00 g of methane with an excess of chlorine?

Accepted Answer

A)   14.2 g
B)   7.10 g
C)   76.7 g
D)   1.42 g
E)   none of these

Question 4

Consider the following unbalanced equation:
C4H10 + O2 → CO2 + H2O
For every 1.0 mol of C4H10, ___ mol of O2 is required.

Accepted Answer

A)   1.0
B)   8.0
C)   13.0
D)   6.5
E)   none of these

Question 5

Sodium perbromate can be synthesized via the following reaction that gives off xenon gas.__NaBrO3 + __XeF2 + __H2O 3 + __XeF2 + __H2O   __NaBrO4 + HF + __Xe What stoichiomatric coefficients should be placed in the blanks above to balance the chemical equation? A)  1, 1, 2, 1, 2, 1 B)  2, 2, 2, 2, 3, 2 C)  3, 2, 1, 3, 2, 1 D)  2, 2, 1, 2, 4, 2 E)  None of the above" class="answers-bank-image d-inline" rel="preload" > __NaBrO4 + HF + __Xe
What stoichiomatric coefficients should be placed in the blanks above to balance the chemical equation?

Accepted Answer

A)   1, 1, 2, 1, 2, 1
B)   2, 2, 2, 2, 3, 2
C)   3, 2, 1, 3, 2, 1
D)   2, 2, 1, 2, 4, 2
E)   None of the above

Question 6

A 7.66-g sample of AgNO3 is reacted with BaCl2 according to the equation
2AgNO3(aq)  + BaCl2(aq)  → 2AgCl(s)  + Ba(NO3) 2(aq) 
To give 4.34 g of AgCl. What is the percent yield of AgCl?

Accepted Answer

A)   47.8%
B)   56.7%
C)   67.2%
D)   33.6%
E)   20.1%

Question 7

The empirical formula of styrene is CH; its molar mass is 104.1. What is the molecular formula of styrene?

Accepted Answer

A)   C2H4
B)   C8H8
C)   C6H6
D)   C10H12
E)   none of these

Question 8

Consider the following unbalanced equation:
KO2 + H2O → KOH + O2 + H2O2
For every 3.0 mol of KO2, ___ mol of H2O is needed for a complete reaction.

Accepted Answer

A)   6.0
B)   2.0
C)   3.0
D)   1.0
E)   none of these

Question 9

A given sample of xenon fluoride contains molecules of a single type, XeFn, where n is some whole number. Given that 9.03 × 1020 molecules of XeFn weigh 0.311 g, calculate n.

Accepted Answer

A)   2
B)   4
C)   1
D)   none of these

Question 10

An alkali metal oxide contains 83.01% metal by mass. Determine the identity of the metal.

Accepted Answer

A)   Cs
B)   Li
C)   K
D)   Na
E)   Rb

Question 11

The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, is a member of this group. The molar mass of lindane is 290.8. How many atoms of carbon does a molecule of lindane contain?

Accepted Answer

A)   6
B)   4
C)   3
D)   8
E)   2

Question 12

The refining of aluminum from bauxite ore (which contains 50.% Al2O3 by mass)  proceeds by the overall reaction 2Al2O3 + 3C → 4Al + 3CO2. How much bauxite ore is required to give the 5.0 × 1013 g of aluminum produced each year in the United States? (Assume 100% conversion.)

Accepted Answer

A)   1.9 × 1014 g
B)   7.6 × 1014 g
C)   1.3 × 1013 g
D)   5.3 × 1013 g

Question 13

For which compound does 0.256 mole weigh 12.9 g?

Accepted Answer

A)   C2H4O2
B)   C2H6
C)   CH3Cl
D)   CO2
E)   C2H4O

Question 14

When the following equation is balanced, what is the sum of the coefficients?
Al2(SO4) 3 + Ca(OH) 2 → Al(OH) 3 + CaSO4

Accepted Answer

A)   10
B)   8
C)   4
D)   9
E)   3

Question 15

A 0.4647-g sample of a compound known to contain only carbon, hydrogen, and oxygen was burned in oxygen to yield 0.8635 g of CO2 and 0.1767 g of H2O. What is the empirical formula of the compound?

Accepted Answer

A)   C3H3O2
B)   C2H2O
C)   C6H3O2
D)   C3H6O2
E)   CHO

Question 16

What is the molar mass of ethanol (C2H5OH) ?

Accepted Answer

A)   46.07
B)   62.07
C)   45.07
D)   38.90
E)   34.17

Question 17

When the equation FeCr2O4 + K2CO3 + O2 → K2CrO4 + Fe2O3 + CO2 is balanced with the smallest set of integers, the sum of the coefficients is

Accepted Answer

A)   9
B)   15
C)   6
D)   37
E)   24

Question 18

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

1.671 × 10...

Question 19

Find the percent sulfur (atoms)  by mass in sodium sulfide.

Accepted Answer

A)   52.1%
B)   58.2%
C)   41.1%
D)   74.4%
E)   73.6%

Question 20

Iron is produced from its ore by the following reactions:
2C(s)  + O2(g)  → 2CO(g) 
Fe2O3(s)  + 3CO(g)  → 2Fe(s)  + 3CO2(g) 
How many moles of C(s)  are needed to produce 2.4 mol Fe(s) ?

Accepted Answer

A)   3.6 mol C
B)   2.4 mol C
C)   5.0 mol ​C
D)   1.6 mol C

Exam 3: Stoichiometry

A given sample of xenon fluoride contains molecules of a single type, XeFn, where n is some whole number. Given that 9.03 × 1020 molecules of XeFn weigh 0.311 g, calculate n.

Correct AnswerverifiedShow Answer

What is the molar mass of ethanol (C2H5OH) ?

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An alkali metal oxide contains 83.01% metal by mass. Determine the identity of the metal.

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For which compound does 0.256 mole weigh 12.9 g?

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​A sample of dysprosium (atomic mass 162.5 u) contains 8 atoms. Determine the mass of the sample.

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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.

Correct Answerverified1.671 × 10...View AnswerShow Answer

Iron is produced from its ore by the following reactions: 2C(s) + O2(g) → 2CO(g) Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) How many moles of C(s) are needed to produce 2.4 mol Fe(s) ?

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When the following equation is balanced, what is the sum of the coefficients? Al2(SO4) 3 + Ca(OH) 2 → Al(OH) 3 + CaSO4

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A 7.66-g sample of AgNO3 is reacted with BaCl2 according to the equation 2AgNO3(aq) + BaCl2(aq) → 2AgCl(s) + Ba(NO3) 2(aq) To give 4.34 g of AgCl. What is the percent yield of AgCl?

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When the equation FeCr2O4 + K2CO3 + O2 → K2CrO4 + Fe2O3 + CO2 is balanced with the smallest set of integers, the sum of the coefficients is

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Consider the following reaction: CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g) What mass of CCl4 is formed by the reaction of 8.00 g of methane with an excess of chlorine?

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Consider the following unbalanced equation: C4H10 + O2 → CO2 + H2O For every 1.0 mol of C4H10, ___ mol of O2 is required.

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The refining of aluminum from bauxite ore (which contains 50.% Al2O3 by mass) proceeds by the overall reaction 2Al2O3 + 3C → 4Al + 3CO2. How much bauxite ore is required to give the 5.0 × 1013 g of aluminum produced each year in the United States? (Assume 100% conversion.)

Correct AnswerverifiedShow Answer

A 0.4647-g sample of a compound known to contain only carbon, hydrogen, and oxygen was burned in oxygen to yield 0.8635 g of CO2 and 0.1767 g of H2O. What is the empirical formula of the compound?

Correct AnswerverifiedShow Answer

What is the subscript of aluminum in the formula of aluminum phosphate?

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The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, is a member of this group. The molar mass of lindane is 290.8. How many atoms of carbon does a molecule of lindane contain?

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Find the percent sulfur (atoms) by mass in sodium sulfide.

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Consider the following unbalanced equation: KO2 + H2O → KOH + O2 + H2O2 For every 3.0 mol of KO2, ___ mol of H2O is needed for a complete reaction.

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The empirical formula of styrene is CH; its molar mass is 104.1. What is the molecular formula of styrene?

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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?

Correct AnswerverifiedShow Answer

A given sample of xenon fluoride contains molecules of a single type, XeF_n, where n is some whole number. Given that 9.03 × 10²⁰ molecules of XeF_n weigh 0.311 g, calculate n.

Correct Answer
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What is the molar mass of ethanol (C₂H₅OH) ?

Correct Answer
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A sample of dysprosium (atomic mass 162.5 u) contains 8 atoms. Determine the mass of the sample.

Correct Answer
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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.

Correct Answer
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1.671 × 10...
View Answer

Iron is produced from its ore by the following reactions: 2C(s) + O₂(g) → 2CO(g) Fe₂O₃(s) + 3CO(g) → 2Fe(s) + 3CO₂(g) How many moles of C₍_s₎ are needed to produce 2.4 mol Fe(s) ?

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When the following equation is balanced, what is the sum of the coefficients? Al₂(SO₄) ₃ + Ca(OH) ₂ → Al(OH) ₃ + CaSO₄

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A 7.66-g sample of AgNO₃ is reacted with BaCl₂ according to the equation 2AgNO₃(aq) + BaCl₂(aq) → 2AgCl(s) + Ba(NO₃) ₂(aq) To give 4.34 g of AgCl. What is the percent yield of AgCl?

Correct Answer
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When the equation FeCr₂O₄ + K₂CO₃ + O₂ → K₂CrO₄ + Fe₂O₃ + CO₂ is balanced with the smallest set of integers, the sum of the coefficients is

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Consider the following reaction: CH₄(g) + 4Cl₂(g) → CCl₄(g) + 4HCl(g) What mass of CCl₄ is formed by the reaction of 8.00 g of methane with an excess of chlorine?

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Consider the following unbalanced equation: C₄H₁₀ + O₂ → CO₂ + H₂O For every 1.0 mol of C₄H₁₀, ___ mol of O₂ is required.

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The refining of aluminum from bauxite ore (which contains 50.% Al₂O₃ by mass) proceeds by the overall reaction 2Al₂O₃ + 3C → 4Al + 3CO₂. How much bauxite ore is required to give the 5.0 × 10¹³ g of aluminum produced each year in the United States? (Assume 100% conversion.)

Correct Answer
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A 0.4647-g sample of a compound known to contain only carbon, hydrogen, and oxygen was burned in oxygen to yield 0.8635 g of CO₂ and 0.1767 g of H₂O. What is the empirical formula of the compound?

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Correct Answer
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Consider the following unbalanced equation: KO₂ + H₂O → KOH + O₂ + H₂O₂ For every 3.0 mol of KO₂, ___ mol of H₂O is needed for a complete reaction.

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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?

Correct Answer
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