Deck 8: Chemical Composition

Question 1

Which represents the greatest number of atoms?

A) 15.0 g S
B) 15.0 g Cu
C) 15.0 g Zr
D) 15.0 g Sc
E) all the same

Answer 1

15.0 g S

Question 2

You have 12.6 g of an unknown substance A and 35.0 g of chlorine gas. Substance A contains 1.5 times as many molecules as the chlorine gas. What is the identity of A?

A) NH₃
B) BF₃
C) O₂
D) CO
E) none of these

Answer 2

NH₃

Question 3

Calculate the mass of 23.7 moles of He.

A) 94.9
B) 27.7
C) 1.43 * 10²⁵
D) 5.92
E) 6.02 *10²³

Answer 3

94.9

Question 4

One atomic mass unit (amu) is the mass (in grams) of one mole of the substance.

Question 5

A 1.50-mol sample of Zr represents how many atoms?

A) 9.03 * 10²³ atoms
B) 2.49 *10^-24 atoms
C) 4.01 *10²³ atoms
D) 8.24 * 10²⁵ atoms
E) 1.64 *10^-2 atoms

Question 6

A 3.37-mol sample of aluminum represents how many atoms?

A) 2.03 *10²⁴ atoms
B) 5.60 *10^-24 atoms
C) 1.25 * 10²³ atoms
D) 5.48 * 10²⁵ atoms
E) none of these

Question 7

One mole of something consists of ____________ units of that substance.

A) 12.01
B) 1.008
C)
D)
E) 32.00

Question 8

A 30.5-g sample of Ca contains how many calcium atoms?

A) 4.58 *10²³ atoms
B) 61.0 atoms
C) 7.61 * 10^-1 atoms
D) 1.84* 10²⁵ atoms
E) 30.5 atoms

Question 9

How many moles of Ca atoms are in 613.3 g Ca?

A) 15.30 mol
B) 6.535 * 10^-2 mol
C) 2.458 * 10⁴ mol
D) 30.60 mol
E) 613.3 mol

Question 10

How many atoms of calcium are present in 58.2 g of calcium?

A) 8.74 *10²³
B) 2.41 *10^-24
C) 3.50 * 10²⁵
D) 6.02 *10²³
E) none of these

Question 11

A 2.35-mole sample of H₂O₂ weighs

A) 79.9 g
B) 2.35 g
C) 36.4 g
D) 42.3 g
E) 42.3 amu

Question 12

The formula of a compound that expresses the smallest whole-number ratio of the atoms present is called the empirical formula.

Question 13

Which represents the greatest mass?

A) 1.0 mol Rb
B) 1.0 mol Ti
C) 1.0 mol Fe
D) 1.0 mol Al
E) all the same

Question 14

The molar mass of ammonium phosphate is

A) 149.09 g/mol
B) 113.01 g/mol
C) 302.95 g/mol
D) 165.09 g/mol
E) 133.09 g/mol

Question 15

You have two beakers on your lab table. Beaker #1 contains 32.07 g of sulfur and Beaker #2 contains 74.92 g of arsenic (As). Which beaker contains the greatest number of atoms? Choose the best answer.

A) Beaker #1 because one sulfur atom weighs less than one arsenic atom so you need more of the sulfur atoms to fill the beaker.
B) Beaker #1 because it contains more moles of sulfur atoms than the number of moles of arsenic atoms in Beaker #2.
C) Beaker #2 because arsenic has a greater mass than sulfur.
D) Beaker #2 because it contains more moles of arsenic atoms than the number of moles of sulfur atoms in Beaker #1.
E) Beakers #1 and #2 contain the same number of atoms because there is one mole in each.

Question 16

What is the mass of 8 atoms of copper in grams?

A) 8.44 * 10^-22 g
B) 1.33 * 10^-23 g
C) 508 g
D) 7.58 *10²² g
E) 63.5 g

Question 17

A 36.6-mol sample of Co represents how many atoms?

A) 2.20 * 10²⁵ atoms
B) 6.08 *10^-23 atoms
C) 1.65 * 10²² atoms
D) 1.30 * 10²⁷ atoms
E) 6.72 * 10² atoms

Question 18

What is the mass of 5.826 moles of Ca(OH)₂?

A) 431.7 g
B) 7.863 * 10^-2 g
C) 12.718 g
D) 863.4 g
E) 74.10 g

Question 19

How many atoms are there in 71.9 g of nickel?

A) 7.38 * 10²³
B) 4.22* 10³
C) 1.23
D) 4.33 * 10²⁵
E) none of these

Question 20

Calculate the mass of 3.53 *10²⁶ atoms of silver.

A) 6.32* 10⁴ g
B) 3.81 * 10²⁸ g
C) 1.97 * 10⁴⁸ g
D) 5.86 *10² g
E) none of these

Question 21

The mass in grams of 3.52 mol of nitrogen gas ( N₂) is

A) 98.6 g/mol
B) 49.3 g/mol
C) 2.12 *10²⁴ g/mol
D) 6.02 * 10²³ g/mol
E) none of these

Question 22

Consider equal mole samples of dinitrogen monoxide, aluminum nitrate, and potassium cyanide. Rank these from least to greatest number of nitrogen atoms in each sample.

A) potassium cyanide, aluminum nitrate, dinitrogen monoxide
B) aluminum nitrate, dinitrogen monoxide, potassium cyanide
C) potassium cyanide, dinitrogen monoxide, aluminum nitrate
D) aluminum nitrate, potassium cyanide, dinitrogen monoxide
E) dinitrogen monoxide, aluminum nitrate, potassium cyanide

Question 23

How many molecules of O₂ are there in 2.2 mol of O₂?

A) 1.3 *10²⁴
B) 3.7 * 10^-24
C) 70
D) 14.55
E) 2.7 *10²³

Question 24

What is the molar mass of nitroglycerin, C₃H₅(NO₃)₃?

A) 227 g/mol
B) 179 g/mol
C) 199 g/mol
D) 185 g/mol
E) none of these

Question 25

What is the molar mass of Ba(OH)₂?

A) 171.35 g/mol
B) 291.67 g/mol
C) 308.68 g/mol
D) 154.34 g/mol
E) 188.36 g/mol

Question 26

The molar mass of strontium hydroxide, Sr(OH)₂ is

A) 121.6 g/mol
B) 192.3 g/mol
C) 209.3 g/mol
D) 105.6 g/mol
E) 104.6 g/mol

Question 27

The molar mass of barium nitrate, Ba(NO₃)₂ is

A) 261.35 g/mol
B) 336.67 g/mol
C) 293.35 g/mol
D) 229.35 g/mol
E) 199.34 g/mol

Question 28

The mass of 0.74 mol of H₂ is

A) 1.5 g
B) 0.74 g
C) 2.7 g
D) 0.37 g
E) none of these

Question 29

The molar mass of AsBr₅ is

A) 474.4 g/mol
B) 154.8 g/mol
C) 774.1 g/mol
D) 454.5 g/mol
E) 399.5 g/mol

Question 30

The term formula weight is also used instead of molar mass for ionic compounds.

Question 31

What is the molar mass of BaBr₂?

A) 297.13 g/mol
B) 354.56 g/mol
C) 217.23 g/mol
D) 434.46 g/mol
E) 594.26 g/mol

Question 32

What is the mass of 1.819 mol of potassium sulfide?

A) 200.6 g
B) 129.4 g
C) 187.8 g
D) 60.62 g
E) none of these

Question 33

What is the molar mass of Li₂SO₄?

A) 109.88 g/mol
B) 77.88 g/mol
C) 102.94 g/mol
D) 93.88 g/mol
E) 198.94 g/mol

Question 34

The molar mass of blood sugar, C₆H₁₂O₆, also known as glucose and dextrose, is

A) 180.16 g/mol
B) 6.02 * 10²³ g/mol
C) 108.10 g/mol
D) 168.06 g/mol
E) none of these

Question 35

A sample of an element with a mass equal to that element's average atomic mass expressed in grams contains one mole of atoms.

Question 36

The molar mass of C₁₀H₂₂ is

A) 142.32 g/mol
B) 130.31 g/mol
C) 120.10 g/mol
D) 286.44 g/mol
E) 130.20 g/mol

Question 37

The molar mass of calcium phosphate, Ca₃(PO₄)₂ is

A) 310.18 g/mol
B) 365.07 g/mol
C) 230.02 g/mol
D) 215.21 g/mol
E) 278.18 g/mol

Question 38

What is the molar mass of C₃H₆O₃?

A) 90.09 g/mol
B) 94.08 g/mol
C) 54.06 g/mol
D) 84.03 g/mol
E) none of these

Question 39

What is the molar mass of Rb₃PO₄?

A) 351.38 g/mol
B) 320.41 g/mol
C) 6.02 *10²³ g/mol
D) 265.91 g/mol
E) 319.38 g/mol

Question 40

What is the molar mass of N₂O?

A) 44.02 g/mol
B) 30.01 g/mol
C) 28.02 g/mol
D) 60.02 g/mol
E) 46.01 g/mol

Question 41

Convert: 7.38 mol Cu(NO₃)₂ = ____________ g Cu(NO₃)₂

A) 1.38 * 10³
B) 25.4
C) 3.93 * 10^-2
D) 1.27 * 10³
E) none of these

Question 42

Convert 47.5 g O₂ to mol O₂.

A) 1.48 mol
B) 0.674 mol
C) 2.97 mol
D) 1.52 *10³ mol
E) 2.86* 10²⁵ mol

Question 43

Convert: 19.9 g NaCl = ____ mol NaCl

A) 0.341
B)
C) 2.94
D)
E) none of these

Question 44

Convert: 11.59 mol CaF₂ = ____ g CaF₂

A) 684.7
B) 904.9
C) 0.1484
D) 6.737
E) none of these

Question 45

Convert: 0.205 mol Ca(OH)₂ = ___________ g Ca(OH)₂

A) 15.2
B) 2.77 *10^-3
C) 11.7
D) 361
E) none of these

Question 46

You have 1.0 mole of each compound below. Which has the greatest mass?

A) sodium hydroxide
B) iron(III) sulfate
C) ammonium nitrate
D) barium carbonate
E) lead(IV) oxide

Question 47

Convert: 92.1 g CO = ____ molecules CO

A)
B)
C)
D)
E)

Question 48

Convert: 460.2 g MgCl₂ = ____ units of MgCl₂

A)
B) 4.834
C)
D)
E)

Question 49

Calculate the mass of 3.64*10¹⁹ molecules of HCl.

A) 2.20 *10^-3 g
B) 6.04* 10^-5 g
C) 2.19 * 10⁴³ g
D) 1.66 * 10^-6 g
E) none of these

Question 50

Convert: 3.248 mol Mg(NO₃)₂ = ____ g Mg(NO₃)₂

A) 429.8
B) 45.67
C) 481.8
D)
E) none of these

Question 51

Convert: 6.911 mol K₂O = _____________ g K₂O

A) 651.0
B) 13.63
C) 7.337 * 10^-2
D) 6.911
E) 4.162 * 10²⁴

Question 52

The number of moles in 20.03 g of C₂H₆O (molar mass = 46.1 g/mol) is

A) 0.835
B) 9.23 * 10²
C) 4.81 * 10²
D) 0.434
E) none of these

Question 53

Convert: 44.4 g NO₂ = ___________ mol NO₂

A) 0.965
B) 2.04 * 10³
C) 2.67 * 10²⁵
D) 44.4
E) 1.04

Question 54

Calculate the mass, in grams, of 1.83 *10²⁶ formula units of sulfur dioxide.

A) 1.95* 10⁴ g
B) 1.17 * 10²⁸ g
C) 3.04 *10² g
D) 4.74 * 10⁰ g
E) none of these

Question 55

Convert: 6.09 g O₃ = ___________ molecules O₃

A) 7.64 *10²²
B) 3.67 * 10²⁴
C) 1.76 *10²⁶
D) 2.11 * 10^-25
E) 1.15 * 10²³

Question 56

Convert: 4.13 mol PCl₅ = ___________ molecules PCl₅

A) 2.49 *10²⁴
B) 6.86 * 10^-24
C) 1.46 *10²³
D) 1.19 * 10²²
E) none of these

Question 57

Calculate the number of moles of water molecules in 72.0 g of water.

A) 4.00 mol
B) 1.30 *10³ mol
C) 0.250 mol
D) 35.7 mol
E) 90.0 mol

Question 58

Convert: molecules NH₃ = ____ mol NH₃

A)
B) 6.68
C) 2.55
D) 0.150
E) none of these

Question 59

Calculate the mass of 5.986 mol of sulfur dioxide.

A) 383.5 g
B) 9.343 * 10^-2 g
C) 10.70 g
D) 3.605 * 10²⁴ g
E) 1.006 *10²³ g

Question 60

A 84.9-g sample of SO₂ contains how many moles of SO₂?

A) 1.33 mol
B) mol
C) mol
D) mol
E) none of these

Question 61

Consider separate 100.0-g samples of each of the following: NH₃, N₂O, HCN, N₂H₄, and HNO₃. Which of the samples has the least mass of nitrogen?

A) NH₃
B) N₂O
C) HCN
D) N₂H₄
E) HNO₃

Question 62

Calculate the mass of 3.663 moles of silver nitrate.

A) g
B) 622.4 g
C) 46.4 g
D) 563.8 g
E) none of these

Question 63

Calculate the percentage composition (by mass) of Mg in Mg₃(AsO₄)₂.

A) 20.8 %
B) 34.4 %
C) 36.3 %
D) 6.9 %
E) 22.9 %

Question 64

Calculate the number of moles of Cl₂ molecules in a sample that contains molecules of Cl₂.

A) mol
B) mol
C) mol
D) 122.6 mol
E) none of these

Question 65

A hydrocarbon has the formula C₅H₁₂. What is the percent by mass of carbon in the compound?

A) 83.2 %
B) 41.6 %
C) 16.8 %
D) 29.4 %
E) 15.7 %

Question 66

A sample with atoms of copper represents how many moles of copper?

A) mol
B) mol
C) mol
D) mol
E) 7.89 mol

Question 67

Calculate the number of molecules in 0.000400 grams of gaseous oxygen.

A) molecules
B) molecules
C) molecules
D) molecules
E) molecules

Question 68

Calculate the number of molecules of CH₄ in 41 g CH₄.

A) molecules
B) molecules
C) molecules
D) molecules
E) none of these

Question 69

How many molecules are present in

A) molecules
B) molecules
C) molecules
D) molecules
E) none of these

Question 70

A 50.3-g sample of H₂O contains how many molecules of water?

A) molecules
B) molecules
C) molecules
D) molecules
E) none of these

Question 71

Compound X₂Y is known to be 60% X by mass. Calculate the percent Y by mass of the compound X₂Y₂.

A) 20%
B) 30%
C) 40%
D) 60%
E) 80%

Question 72

The mole can be defined as the number equal to the number of oxygen atoms in 32.00 g of oxygen.

Question 73

How many moles of Al₂O₃ are present in 78.8 g of this compound?

A) mol
B) 0.773 mol
C) 1.29 mol
D) mol
E) mol

Question 74

A gaseous compound containing carbon and hydrogen was analyzed and found to consist of 83.65% carbon by mass. What is the empirical formula of the compound?

A) CH₂
B) CH₃
C) C₇H₁₆
D) CH
E) C₃H₇

Question 75

Calculate the mass of 0.314 mol of H₂SO₄.

A) g
B) 30.8 g
C) g
D) g
E) g

Question 76

Calculate the number of moles of CH₄ in 67 g CH₄.

A) 0.24 mol
B) mol
C) mol
D) mol
E) 4.2 mol

Question 77

A 60.2-mL sample of Hg (density = 13.6 g/mL) contains how many atoms of Hg?

A) atoms
B) atoms
C) atoms
D) atoms
E) none of these

Question 78

Calculate the mass of sulfur in 1.74 mol of H₂SO₄.

A) g
B) 18.4 g
C) 55.8 g
D) g
E) g

Question 79

Calculate the number of moles in 2.28 g Rb₂C₂O₄.

A) mol
B) 113.6 mol
C) mol
D) mol
E) mol

Question 80

A gaseous compound containing carbon and hydrogen was analyzed and found to consist of 83.65% carbon by mass. The molar mass of the compound is 86.2 g/mol. What is the molecular formula of the compound?

A) C₃H₇
B) CH₂
C) C₂H₄
D) C₆H₁₄
E) C₁₈H₂₁