Question 1

A compound has a molar mass of 180.15 g/mol.Given the following percent composition,calculate the molecular formula:

Accepted Answer

A)  CH3O2
B)  CH2O
C)  C3H6O3
D)  C6H12O6
E)  none of the aboveF) B) and C)
G) A) and B)

Question 2

A 7.96 gram sample of silver reacts with oxygen to form 8.55 gram of the metal oxide.What is the formula of the oxide?

Accepted Answer

A)  AgO
B)  AgO2
C)  Ag2O
D)  Ag3O
E)  none of the aboveF) A) and C)
G) A) and E)

Question 3

An iron chloride compound contains 55.85 grams of iron and 106.5 grams of chlorine.What is the most likely empirical formula for this compound?

Accepted Answer

A)  FeCl
B)  FeCl2
C)  Fe2Cl
D)  FeCl3
E)  Fe3ClF) A) and E)
G) B) and C)

Question 4

The mass of 2.0 moles of H2O is greater than the mass of 1.0 mole of CO2.

Accepted Answer

A) True 
 B)False

Question 5

You have 10.0 g each of Na,C,Pb,Cu and Ne.Which contains the smallest number of moles?

Accepted Answer

A)  Na
B)  C
C)  Pb
D)  Cu
E)  NeF) C) and D)
G) A) and E)

Question 6

Vitamin C is known chemically by the name ascorbic acid.Determine the empirical formula of ascorbic acid if it is composed of 40.92% carbon,4.58% hydrogen,and 54.50% oxygen.

Accepted Answer

A)  CHO
B)  CH2O
C)  C2H3O2
D)  C3H4O3
E)  none of the aboveF) B) and C)
G) A) and E)

Question 7

One mole of nitrogen gas contains (2)× (6.022 × 1023)nitrogen atoms.

Accepted Answer

A) True 
 B)False

Question 8

How many moles of iron are contained in 1.75 kg of iron?

Accepted Answer

A)  3.13 × 10-2
B)  3.13 × 10-4
C)  31.3
D)  3.13 × 104
E)  none of the aboveF) All of the above
G) A) and E)

Question 9

What is the mass percent of hydrogen in water?

Accepted Answer

A)  33.3
B)  88.8
C)  5.60
D)  11.2
E)  none of the aboveF) A) and B)
G) C) and D)

Question 10

What is the mass percent of oxygen in sodium oxide?

Accepted Answer

A)  17.0
B)  25.8
C)  44.4
D)  39.7
E)  none of the aboveF) B) and E)
G) A) and C)

Question 11

The empirical formula mass is 18.0 and the molecular formula mass is 90,therefore n = 5.

Accepted Answer

A) True 
 B)False

Question 12

An iron ore sample is found to be 35.00% Fe by mass.How many grams of ore are needed to obtain 
Of Fe?

Accepted Answer

A)  1297
B)  158.9
C)  295.1
D)  350.0
E)  none of the aboveF) A) and E)
G) C) and D)

Question 13

If 3.011 × 1023 molecules have a mass of 20.04 grams,what is the molar mass of this substance?

Accepted Answer

A)  40.08 g/mol
B)  10.02 g/mol
C)  20.04 g/mol
D)  6.658 × 10-23 g/mol
E)  none of the aboveF) B) and E)
G) All of the above

Question 14

What is the mass of 3.91 x 1024 sulfur atoms?

Accepted Answer

A)  208
B)  4.93
C)  155
D)  32.07
E)  none of the aboveF) A) and B)
G) None of the above

Question 15

How many moles are there in 82.5 grams of iron?

Accepted Answer

A)  4.97 × 1025
B)  55.85
C)  0.677
D)  1.48
E)  none of the aboveF) A) and E)
G) All of the above

Question 16

Determine the correct empirical formula of a compound containing 26.68% carbon,2.24% hydrogen,and 71.08% oxygen.

Accepted Answer

A)  CHO
B)  CHO2
C)  C0.5H0.5O1
D)  C2H2O4
E)  none of the aboveF) B) and E)
G) B) and C)

Question 17

Two moles of cobalt atoms have a mass of 117.87 grams.

Accepted Answer

A) True 
 B)False

Question 18

How many moles are there in 17.5 grams of sodium?

Accepted Answer

A)  22.99
B)  1.05 × 1025
C)  0.761
D)  1.31
E)  none of the aboveF) A) and B)
G) C) and D)

Question 19

Six grams of carbon contains 3.008 × 1023 atoms.

Accepted Answer

A) True 
 B)False

Question 20

How many atoms are in 1.50 moles of fluorine gas?

Accepted Answer

A)  6.022 × 1023
B)  9.03 × 1023
C)  18.98
D)  1.81 × 1024
E)  none of the aboveF) D) and E)
G) B) and C)

Exam 6: Chemical Composition

Two moles of cobalt atoms have a mass of 117.87 grams.

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An iron ore sample is found to be 35.00% Fe by mass.How many grams of ore are needed to obtain Of Fe?

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An iron chloride compound contains 55.85 grams of iron and 106.5 grams of chlorine.What is the most likely empirical formula for this compound?

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Determine the correct empirical formula of a compound containing 26.68% carbon,2.24% hydrogen,and 71.08% oxygen.

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A 7.96 gram sample of silver reacts with oxygen to form 8.55 gram of the metal oxide.What is the formula of the oxide?

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A compound has a molar mass of 180.15 g/mol.Given the following percent composition,calculate the molecular formula:

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One mole of nitrogen gas contains (2)× (6.022 × 1023)nitrogen atoms.

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The mass of 2.0 moles of H2O is greater than the mass of 1.0 mole of CO2.

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How many moles are there in 82.5 grams of iron?

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If 3.011 × 1023 molecules have a mass of 20.04 grams,what is the molar mass of this substance?

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Vitamin C is known chemically by the name ascorbic acid.Determine the empirical formula of ascorbic acid if it is composed of 40.92% carbon,4.58% hydrogen,and 54.50% oxygen.

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What is the mass percent of oxygen in sodium oxide?

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How many atoms are in 1.50 moles of fluorine gas?

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The empirical formula mass is 18.0 and the molecular formula mass is 90,therefore n = 5.

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How many moles are there in 17.5 grams of sodium?

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How many moles of iron are contained in 1.75 kg of iron?

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Six grams of carbon contains 3.008 × 1023 atoms.

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What is the mass percent of hydrogen in water?

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What is the mass of 3.91 x 1024 sulfur atoms?

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You have 10.0 g each of Na,C,Pb,Cu and Ne.Which contains the smallest number of moles?

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One mole of nitrogen gas contains (2)× (6.022 × 10²³)nitrogen atoms.

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The mass of 2.0 moles of H₂O is greater than the mass of 1.0 mole of CO₂.

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If 3.011 ×10²³ molecules have a mass of 20.04 grams,what is the molar mass of this substance?

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Six grams of carbon contains 3.008 × 10²³ atoms.

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What is the mass of 3.91 x 10²⁴ sulfur atoms?

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