Deck 9: Stoichiometry and the Mole

Question 1

Which of the following has the least number of atoms?

A)(NH₄)₃PO₄
B)Na₂P₂O₃
C)(NH₄)₂Cr₂O₇
D)K₄Fe(CNO)₆

Answer 1

Na₂P₂O₃

Question 2

The molar mass of a compound Al₂(XO₄)₃ is 342. The atomic mass of X is ________, which is ________.

A)31; P
B)32; S
C)52; Cr
D)55; Mn

Answer 2

32; S

Question 3

Which of the following has the greatest number of atoms?

A)(NH₄)₃PO₄
B)Na₂P₂O₃
C)(NH₄)₂Cr₂O₇
D)K₄Fe(CNO)₆

Answer 3

K₄Fe(CNO)₆

Question 4

What is the mass in grams of 1.000 mole of P₂O₅?

A)239.03 g
B)61.96 g
C)141.96 g
D)46.98 g

Question 5

What is the mass in grams of 1.000 mole of a compound whose formula is C₃H₇O₂?

A)29 g
B)68 g
C)38 g
D)75 g

Question 6

The molecular mass of a compound X(NO₃)₃ is 213. The atomic mass of X is ________, which is ________.

A)27; Al
B)51; V
C)56; Fe
D)59; Co

Question 7

Which of the following has the highest molar mass?

A)(NH₄)₃PO₃
B)Ca₃(PO₄)₂
C)Al₂(SO₃)₃
D)Co₂(CO₃)₂

Question 8

Alkanes have the general molecular formula C_nH_2n+2. Thus, when n= 1, the alkane is CH₄, when n=2, the alkane is C₂H₆ etc. If an alkane has a molar mass between 140 and 150, this alkane is ________.

A)C₉H₂₀
B)C₁₂H₂₆
C)C₁₀H₂₂
D)C₁₁H₂₄

Question 9

What is the percentage by mass of hydrogen in ordinary water (H₂O)?

A)20%
B)11%
C)60%
D)40%

Question 10

Ilmenite (FeTiO₃)is the primary ore from which the element titanium (Ti)is isolated. What is the percentage of titanium by mass in this mineral?

A)20%
B)32%
C)80%
D)68%

Question 11

What is the molecular formula of a compound that weighs 46 g/mol and analyzes to 52.2% C, 34.8% O, and 13% H?

A)C₃H₂O₂
B)C₂H₆O
C)CH₃O
D)C₂H₅O₂

Question 12

The correct sequence of decreasing number of atoms per formula unit in the following is ________.

A)(NH₄)₃PO₄ > Na₂P₂O₃ > Na₃PO₄
B)Na₃PO₄ > (NH₄)₃PO₄ > Na₂P₂O₃
C)Na₂P₂O₃ > Na₃PO₄ > (NH₄)₃PO₄
D)(NH₄)₃PO₄ > Na₃PO₄ > Na₂P₂O₃

Question 13

What is the percentage by mass of iron (Fe)in the mineral hematite (Fe₂O₃)?

A)40%
B)60%
C)70%
D)30%

Question 14

The molar mass for Pb(CO₃)₄ is ________.

A)447
B)409
C)327
D)303

Question 15

The number of oxygen atoms in 1 mole Al₂(SO₄)₃ is ________.

A)3
B)4
C)12
D)none of the above

Question 16

Alkynes have the general molecular formula C_nH_2n-2. Thus, when n= 2, the alkyne is C₂H₂ etc. If an alkyne has a molecular mass between 75 and 85, this alkyne is ________.

A)C₆H₁₀
B)C₆H₁₂
C)C₅H₁₆
D)C₇H₁₂

Question 17

The molar mass of a compound XClO₃ is 106.5. The molar mass (rounded to the nearest whole number)of X is ________, which is ________.

A)39; K
B)23; Na
C)7; Li
D)1; H

Question 18

Which of the following has a molar mass equal to 133?

A)(NH₄)₃PO₃
B)Ca₃(PO₄)₂
C)Al₂(SO₃)₃
D)Co₂(CO₃)₂

Question 19

Which of the following pairs does not share the same molecular mass when rounded to the nearest whole number?

A)CH₃OH and oxygen gas
B)CO and nitrogen gas
C)C₂H₆O and C₂H₄O₂
D)C₄H₁₀O and C₃H₆O₂

Question 20

The molar mass of a compound Ca(MO₃)₂ is 160. The atomic mass of M is ________, which is ________.

A)12; C
B)14; N
C)32; S
D)35; Cl

Question 21

A sample of calcium that contains four times Avogadro's number of atoms has a mass of ________.

A)20 g
B)40 g
C)80 g
D)160 g

Question 22

A sample of oxygen gas that contains twice Avogadro's number of molecules has a mass of ________.

A)8.0 g
B)16.0 g
C)32.0 g
D)64.0 g

Question 23

0.3 moles of a certain calcium compound weigh 93 g. This compound may be ________.

A)calcium nitrate
B)calcium chromate
C)calcium phosphate
D)calcium sulfate

Question 24

A sample of methane gas that contains Avogadro's number of molecules has a mass of ________.

A)8.0 g
B)16.0 g
C)32.0 g
D)64.0 g

Question 25

Which of the following quantities does not share the same molar mass as the others when rounded to the nearest whole number?

A)Al₂(SO₄)₃
B)C₁₂H₂₂O₁₁
C)C₂₄H₃₈O
D)Pb₃(PO₄)₄

Question 26

A sample of oxygen gas that contains one-half of Avogadro's number of molecules has a mass of ________.

A)8.0 g
B)16.0 g
C)32.0 g
D)64.0 g

Question 27

A sample of methane gas that contains Avogadro's number of atoms has a mass of ________.

A)3.2 g
B)6.4 g
C)16.0 g
D)80.0 g

Question 28

Which of the following does not have the same number atoms as the other three choices?

A)three moles Na₂SO₃
B)six moles of water
C)nine moles NaCl
D)five moles CH₄

Question 29

Which of the following contains the least number of atoms?

A)1.0 mole C₆H₁₄
B)3.0 moles N₂O₅
C)12.0 moles silver
D)3.0 moles water

Question 30

12 g of carbon is equal to ________.

A)the mass of one atom
B)the mass of one molecule
C)the mass of one mole
D)the mass of half a mole

Question 31

Which of the following contains the greatest number of atoms?

A)1.0 mole C₆H₁₄
B)3.0 moles N₂O₅
C)12.0 moles silver
D)3.0 moles water

Question 32

A sample of oxygen gas that contains Avogadro's number of molecules has a mass of ________.

A)8.0 g
B)16.0 g
C)32.0 g
D)64.0 g

Question 33

0.02 moles of a certain aluminum compound has a mass of 1.56 g. This compound may be ________.

A)aluminum hydroxide
B)aluminum nitrate
C)aluminum cyanide
D)aluminum permanganate

Question 34

Which of the following will not have the same number atoms as the other three choices?

A)K₂Cr₂O₇
B)(NH₄)₂S
C)Al(ClO₂)₃
D)Ba(HCO₃)₂

Question 35

0.05 moles of a certain compound has a mass of 17.1 g. This compound may be ________.

A)aluminum sulfate
B)lead (II)chloride
C)cobalt (III)oxide
D)magnesium carbonate

Question 36

A sample of calcium that contains Avogadro's number of atoms has a mass of ________.

A)20 g
B)40 g
C)80 g
D)160 g

Question 37

A sample of calcium that contains one-half Avogadro's number of atoms has a mass of ________.

A)20 g
B)40 g
C)80 g
D)160 g

Question 38

What is the molecular mass of a compound X if 0.0400 moles weigh 21.6 g?

A)540
B)185
C)216
D)864

Question 39

The number of atoms in 2.4 g of magnesium metal is ________.

A)6.0 × 10²²
B)3.7 × 10²²
C)2.5 × 10²²
D)1.7 × 10²²

Question 40

A sample of calcium that contains twice Avogadro's number of atoms has a mass of ________.

A)20 g
B)40 g
C)80 g
D)160 g

Question 41

One molecule of water contains ________.

A)one mole of hydrogen
B)one mole of oxygen
C)one atom of oxygen
D)16 g of oxygen

Question 42

The element in C₇H₅NO₃ whose % composition is 31.8% is ________.

A)carbon
B)hydrogen
C)nitrogen
D)oxygen

Question 43

The number of oxygen atoms present in 32.4 g N₂O₅ is ________.

A)5.0
B)9.0 × 10²³
C)4.5 × 10²³
D)1.8 × 10²³

Question 44

A certain food contains 60 mg of table salt. This is approximately equal to ________ formula units.

A)6 × 10²³
B)6 × 10²²
C)6 × 10²⁰
D)6 × 10²⁶

Question 45

Which statement is true about the empirical formula?

A)The empirical formula is always different than the molecular formula.
B)The empirical formula is always the same as the molecular formula.
C)The empirical formula may be different than the molecular formula.
D)The empirical formula cannot be determined solely by the % composition.

Question 46

The mass of one formula unit of Al₂(SO₄)₃ is ________ g.

A)342
B)0.0029
C)5.7 × 10^-22
D)8.0 × 10^-27

Question 47

5.82 g isopropyl alcohol yield 7.001 g water and 12.6 g carbon dioxide upon combustion. The empirical formula is ________.

A)CH₂O
B)C₃H₈O
C)C₂H₆O
D)C₃H₉O

Question 48

A certain compound has the following composition: C= 40.0% and H= 6.7%. The empirical formula is ________.

A)CH
B)CH₂O
C)C₆H₆O
D)CHO

Question 49

Which of the following pairs does not share the same empirical formula?

A)CH₂O and C₃H₆O₃
B)C₆H₆ and C₂H₂
C)C₂H₆O and CH₃O
D)C₃H₄Br₂ and C₉H₁₂O₆

Question 50

Which compound has the following % composition Al= 15.8%, 28.1% S and 56.1% O?

A)Al₂(SO₄)₃
B)Al₂(SO₃)₃
C)Al₂S₃
D)Al₂(S₂O₃)₃

Question 51

Which of the following has its empirical formula different than its molecular formula?

A)CH₂S
B)C₂H₇N₃
C)C₃H₆N₃
D)C₅H₇O₃

Question 52

Which is the correct statement about one mole of ammonia, NH₃?

A)It contains 14 g nitrogen and 3 g hydrogen.
B)It contains 6.02 × 10²³ molecules.
C)It contains 1.8 × 10²⁴ atoms of hydrogen.
D)all of the above

Question 53

If the empirical formula of a compound is CH₂O and the molecular weight is 180, the molecular formula is ________.

A)CH₂O
B)C₂H₄O₂
C)C₃H₆O₃
D)C₆H₁₂O₆

Question 54

The number of phosphorus atoms in one molecule of H₃PO₄ is ________.

A)1
B)8
C)6.02 × 10²³
D)4.8 × 10²³

Question 55

A sample is composed of 2.78 g iron and 1.19 g oxygen. The empirical formula is ________.

A)FeO₂
B)Fe₂O₅
C)Fe₂O₃
D)FeO

Question 56

Which of the following does not share the same empirical formula as the other three?

A)CH₂O
B)C₆H₁₂O₆
C)C₈H₁₆O₈
D)C₁₂H₂₂O₁₁

Question 57

Which contains more carbon?

A)24 g methane
B)140 g sodium carbonate
C)40 g carbon monoxide
D)15 g octane, C₈H₁₈

Question 58

A compound is found to be 43.7% phosphorus and 56.3% oxygen. Given the molecular mass as 285 ± 10, calculate the empirical and molecular formulas?

A)PO₂; P₄O₈
B)P₂O₅; P₄O₁₀
C)P₂O₃; P₆O₉
D)P₄O₁₀; P₄O₁₀

Question 59

Which of the following does not contain 3.0 × 10²⁴ atoms?

A)60 g of carbon
B)one mole of methane
C)two moles of water
D)160 g sulfur

Question 60

Which statement is true when comparing acetic acid C₂H₄O₂ and formaldehyde CH₂O?

A)Their empirical formulas are identical.
B)Their molecular formulas are identical.
C)Their molecular formulas are different.
D)both A and C

Question 61

Which of the following % compositions does not correspond to one of the elements of C₆H₁₂O₆?

A)43.4%
B)40.0%
C)6.7%
D)53.3%

Question 62

Which contains the highest % of oxygen?

A)H₂O₂
B)Na₂O₂
C)HgO
D)CO₂

Question 63

A chromium-silicon compound contains 73.52% chromium. The empirical formula is ________.

A)CrSi
B)CrSi₂
C)Cr₂Si
D)Cr₃Si₂

Question 64

Which of the following compounds has its oxygen composition equal to 50.0%?

A)(NH₄)₂CO₃
B)CH₂O₂
C)C₂H₃NO₂
D)C₁₀H₂₀ONS

Question 65

Which contains the least % of oxygen?

A)H₂O₂
B)Na₂O₂
C)HgO
D)CO₂

Question 66

Which contains the highest % of hydrogen?

A)HCl
B)H₂SO₄
C)H₃PO₄
D)H₂O

Question 67

An iron oxide is 70.0% in iron. Its empirical formula is ________.

A)FeO
B)Fe₂O
C)Fe₂O₃
D)Fe₃O₄

Question 68

Which of the following has the lowest % oxygen composition?

A)N₂O
B)Al₂O₃
C)K₂CO₃
D)KMnO₄

Question 69

An iron oxide is 77.7% in iron. Its empirical formula is ________.

A)FeO
B)Fe₂O
C)Fe₂O₃
D)Fe₃O₄

Question 70

What is the mass of sulfur that will react with 0.527 copper metal to yield copper (I)sulfide?

A)0.066 g
B)0.132 g
C)0.264 g
D)0.198 g

Question 71

Which of the following compounds has its carbon composition equal to 52.2%?

A)C₂H₆O
B)CH₃Cl
C)C₄H₈O₂N₂S
D)C₁₀H₂₀O₄N₂S

Question 72

Which of the following compounds has its combined carbon and oxygen composition equal to 76.7%?

A)C₄H₇Cl
B)CH₂O₂
C)C₂H₃NO₂
D)C₁₀H₂₀ONS

Question 73

Which of the following compounds has its chlorine composition equal to 83.5%?

A)C₂H₃ClO₂
B)C₁₀H₁₇ClS
C)CCl₄
D)CH₂Cl₂

Question 74

An iron oxide is 72.4% in iron. Its empirical formula is ________.

A)FeO
B)Fe₂O
C)Fe₂O₃
D)Fe₃O₄

Question 75

Which of the following compounds has its combined carbon and hydrogen composition equal to 37.0%?

A)C₄H₇Cl
B)CH₂O₂
C)C₂H₃NO₂
D)C₁₀H₂₀ONS

Question 76

Which of the following has the highest % oxygen composition?

A)N₂O
B)Al₂O₃
C)K₂CO₃
D)KMnO₄

Question 77

Which of the following compounds is expected to have oxygen?

A)compound W: %C= 40.2% ; H= 6.8%; N= 10.3%; S= 19.2%
B)compound X: %C= 52.3% ; H= 4.1%; Br= 30.4%; S= 13.2%
C)compound Y: %C= 25.6% ; H= 8.8%; I= 45.3%; N= 20.2%
D)compound Z: %C= 48.1% ; H= 8.6%; F= 28.2%; P= 15.0%

Question 78

Which of the following compounds has its nitrogen composition equal to 29.2%?

A)C₂H₃NO₂
B)C₁₀H₂₀ONS
C)(NH₄)₂CO₃
D)N₂H₄

Question 79

Which of the following compounds has its hydrogen composition equal to 2.4%?

A)C₄H₇Cl
B)CH₂Cl₂
C)C₂H₃NO₂
D)C₁₀H₂₀ONS

Question 80

The mass of oxygen present in 11.7 g Al₂(CO₃)₃ is ________.

A)7.2 g
B)14.4 g
C)8.1 g
D)4.0 g