Deck 7: Chemical Formula Relationships

Question 1

How many atoms are in 0.188 mol Na?

A)3.12 * 10^-25
B)8.84* 10^-24
C)1.13 * 10²³
D)6.02 *10²³
E)3.20 * 10²⁴

Answer 1

1.13 * 10²³

Question 2

Calculate the molar mass of ammonium sulfide.

A)68.15 g/mol
B)82.16 g/mol
C)49.10 g/mol
D)50.11 g/mol
E)66.14 g/mol

Answer 2

68.15 g/mol

Question 3

Calculate the formula mass of magnesium phosphate.

A)119.28 u
B)143.59 u
C)214.25 u
D)262.87 u
E)333.53 u

Answer 3

262.87 u

Question 4

Which of the following statements is/are correct?
(i)A mole of sodium atoms (atomic mass = 23.0 u)contains fewer atoms than a mole of potassium atoms (atomic mass = 39.1 u)
(ii)A mole of sodium atoms (atomic mass = 23.0 u)contains more atoms than a mole of potassium atoms (atomic mass = 39.1 u)
(iii)In effect,the word mole represents the number 6.02 * 10²³
(iv)One mole of a substance contains as many particles as there are atoms in 12 grams of carbon-12
(v)One mole of molecular nitrogen contains as many molecules as 24.0 u of carbon-12

A)i and iii
B)ii and iii
C)i and iv
D)iii and iv
E)ii,iii,iv,and v

Question 5

The following two containers are found on a stock room counter. How many atoms of nitrogen are in a formula unit of each from left to right,respectively?

A)1 nitrogen atom,1 nitrogen atom
B)1 nitrogen atom,2 nitrogen atoms
C)2 nitrogen atoms,1 nitrogen atoms
D)2 nitrogen atoms,2 nitrogen atoms
E)3 nitrogen atoms,6 nitrogen atoms

Question 6

Calculate the formula mass of aluminum carbonate.

A)87.0 u
B)114.0 u
C)147.0 u
D)201.0 u
E)234.0 u

Question 7

Consider the following molecule.The identity of the atoms are shown. What is the molar mass of this substance?

A)22.00 g/mol
B)56.02 g/mol
C)28.01 g/mol
D)76.01 g/mol
E)44.01 g/mol

Question 8

Which of the following statements is incorrect?

A)Molecular mass is expressed in atomic mass units
B)Formula mass compares the mass of one formula unit of a substance to the mass of one atom of carbon-12
C)Atomic mass has units of grams per atom
D)Both molecular mass and formula mass use carbon-12 as a reference standard
E)Sodium chloride,an ionic compound,is said to have a formula weight,but not a molecular weight

Question 9

Which off the following provides the conversion factor to convert 10.7 g of sulfur dioxide to the corresponding number of moles of sulfur dioxide?

A)molar mass
B)molecular mass
C)formula mass
D)Avogadro's number
E)either a or c

Question 10

Calculate the molar mass of molecular iodine.

A)126.9 g/mol
B)253.8 g/mol
C)79.9 g/mol
D)159.8 g/mol
E)Only atomic masses,and not molar masses,can be calculated for elements

Question 11

For which of the following compounds is the term formula mass better suited than the term molecular mass?
(i)F₂
(ii)CaO
(iii)NH₃
(iv)NaOH
(v)CH₃OH

A)ii only
B)ii and iv
C)i and iii
D)ii,iv and v
E)i,iii,and v

Question 12

Which of the following is the best definition of atomic mass?

A)The average mass of the atoms of an element compared to the mass of an atom of carbon-12 at exactly 12 atomic mass units
B)A property reflecting the quantity of matter in a sample
C)The mass of an atom measured in the SI unit of mass,the kilogram
D)The number of grams in a mole of a substance
E)The mass of the number of carbon atoms in exactly 12 grams of carbon-12

Question 13

How many molecules are in 0.105 mol NH₃?

A)6.32 * 10²²
B)5.73 * 10²⁴
C)1.74 *10^-25
D)1.58 * 10^-23
E)1.79

Question 14

Which of the following statements is/are correct?
(i)One mole of a substance contains as many particles as exactly 12 u of carbon-12
(ii)A mole of iodine atoms contains fewer atoms than a mole of bromine atoms
(iii)There are 6.02 *10²³ carbon atoms in 12.0 grams of carbon-12
(iv)Because both use carbon-12 as a reference,one mole of a low molecular mass substance contains more particles than one mole of a high molecular mass substance
(v)One mole of a substance contains 6.02*10²³ particles of that substance

A)i and iii
B)i and v
C)iii and v
D)ii and iv
E)ii and v

Question 15

Consider the following laboratory chemical. What is the molecular mass of this substance?

A)31.02 u
B)63.02 u
C)47.02 u
D)126.04 u
E)110.01 u

Question 16

How many moles are in 6.27 *10²⁴ formula units of sodium nitrate?

A)0.0960
B)10.4
C)85.0
D)3.77 * 10⁴⁸
E)2.65 *10^-49

Question 17

Which of the following statements is/are incorrect?

A)One mole is that amount of any substance that contains the same number of units as the number of atoms in exactly 12 grams of carbon-12
B)To three significant figures,there are 6.02 * 10²³ units per mole
C)The number of particles in a mole is called Avogadro's number
D)The mass of 1/12 mole of carbon-12 is 1 gram
E)The mole is a fundamental constant derived from the laws of nature

Question 18

List the number of atoms of each element in a formula unit of ammonium sulfate.

A)1 nitrogen atom,4 hydrogen atoms,1 sulfur atom,4 oxygen atoms
B)1 nitrogen atom,3 hydrogen atoms,1 sulfur atom,4 oxygen atoms
C)2 nitrogen atoms,6 hydrogen atoms,1 sulfur atom,4 oxygen atoms
D)2 nitrogen atoms,8 hydrogen atoms,1 sulfur atom,4 oxygen atoms
E)1 nitrogen atom,4 hydrogen atoms,2 sulfur atoms,8 oxygen atoms

Question 19

Which of the following statements is/are correct?

A)Because it is the standard,carbon has a molar mass of exactly one gram per mole
B)The phrase "molar mass of iodine" is not ambiguous,but the phrase "molar mass of potassium" is ambiguous
C)The molar mass of a substance is the mass in grams of one mole of the substance
D)The formula masses of ionic compounds are always larger,numerically,than the molar masses of those compounds
E)None of the above is correct

Question 20

How many atoms of each element are in a formula unit of magnesium phosphate?

A)3 magnesium atoms,2 phosphorus atoms,8 oxygen atoms
B)2 magnesium atoms,3 phosphorus atoms,12 oxygen atoms
C)1 magnesium atom,1 phosphorus atom,4 oxygen atoms
D)2 magnesium atoms,1 phosphorus atom,4 oxygen atoms
E)1 magnesium atom,2 phosphorus atoms,8 oxygen atoms

Question 21

What is the mass of 0.0490 mole of potassium sulfate?

A)0.0490 g
B)3.55 kg
C)6.62 g
D)8.54 g
E)174.3 g

Question 22

How many grams of oxygen are in 8.50 g of formaldehyde,CH₂O?

A)2.12 g
B)2.83 g
C)4.25 g
D)4.53 g
E)16.0 g

Question 23

What is the mass of 7.24 *10²³ formula units of barium oxide?

A)7.85 * 10^-3 g
B)1.84 * 10² g
C)1.11 *10²⁶ g
D)2.84 * 10⁴⁵ g
E)6.68 *10⁴⁹ g

Question 24

A compound analyzes as 18.0% carbon,2.26% hydrogen,and 79.7% chlorine.Calculate the empirical formula of the compound.

A)C₄H₃Cl₄
B)C₃H₂Cl₂
C)C₃H₃Cl₂
D)C₂H₂Cl₃
E)C₂H₃Cl₃

Question 25

Calculate the percent composition of aluminum oxide.

A)47.1% Al,52.9% O
B)52.9% Al,47.1% O
C)28.3% Al,71.7% O
D)71.1% Al,28.3% O
E)62.8% Al,37.2% O

Question 26

Calculate the percentage composition of calcium chlorate.

A)19.4% Ca,34.3% Cl,46.4% O
B)32.4% Ca,28.7% Cl,38.8% O
C)49.0% Ca,21.8% Cl,29.3% O
D)32.4% Ca,67.6% ClO₃
E)49.0% Ca,51.0% ClO₃

Question 27

Calculate the number of atoms in 0.377 grams of Ar.

A)1.57 * 10^-26
B)2.50 *10^-23
C)5.67 * 10²¹
D)9.08 * 10²⁴
E)9.42 *10^-3

Question 28

From the following,pick those that are not empirical formulas.
(i)C₂H₈
(ii)C₂H₃
(iii)C₆H₆
(iv)C₇H₆
(v)C₇H₂₁

A)i and ii
B)ii and iv
C)iv and v
D)i,iii,and v
E)i,ii,and iii

Question 29

A certain compound is 66.7% carbon,3.74% hydrogen,and 29.6% oxygen.Find the empirical formula.

A)C₃H₂O
B)C₃HO
C)CHO
D)CH₂O
E)CH₃O₃

Question 30

Calculate the mass of silver in a sample of silver sulfide that contains 0.890 g of sulfur.

A)1.08 g
B)1.78 g
C)3.00 g
D)5.99 g
E)6.89 g

Question 31

How much silver nitrate must be measured to yield 1.00 g silver?

A)1.00 g
B)1.57 g
C)1.70 g
D)2.00 g
E)0.635 g

Question 32

Calculate the percent nitrogen in ammonium nitrate.

A)17.5%
B)21.9%
C)22.9%
D)33.3%
E)35.0%

Question 33

Which of the following are empirical formulas?
(i)C₁₀H₈
(ii)CH₂
(iii)Al₂Cl₆
(iv)NO₂
(v)Hg₂Cl₂

A)i only
B)i and ii
C)ii and iv
D)i,ii,and v
E)iii,iv,and v

Question 34

Calculate the percent mercury and nitrogen in mercury(II)cyanide.The formula of the cyanide ion is CN^-.

A)20.0% Hg,40.0% N
B)79.4% Hg,6.2% N
C)79.4% Hg,11.1% N
D)83.4% Hg,11.6% N
E)88.5% Hg,6.2% N

Question 35

How many grams of calcium are in 5.00 g of calcium hydroxide?

A)0.541 g
B)2.50 g
C)2.70 g
D)3.51 g
E)40.1 g

Question 36

What is the empirical formula of a compound that contains 80.0% carbon and 20.0% hydrogen by mass?

A)CH₃
B)CH₂
C)CH
D)C₃H
E)C₂H₃

Question 37

A coolant widely used in automobile engines is 38.7% carbon,9.7% hydrogen,and 51.6% oxygen.Calculate the empirical formula for the compound.

A)C₃HO₃
B)C₂H₃O₂
C)C₂H₃O
D)CH₃O
E)CHO

Question 38

Calculate the number of moles in 15.8 grams of aluminum hydroxide.

A)1232 mol
B)727 mol
C)15.8 mol
D)0.343 mol
E)0.203 mol

Question 39

Examine the following molecule.The component atoms are labeled. What is the empirical formula for this substance?

A)SbCl₂
B)SbCl₃
C)Sb₂Cl₆
D)SbCl
E)Sb₂Cl

Question 40

From the following,pick those that are empirical formulas.
(i)KCl
(ii)K₂S₂O₈
(iii)K₂SO₄
(iv)K₄S₂
(v)KIO₃

A)i and v
B)ii and iv
C)iii and iv
D)iv and v
E)i,iii,and v

Question 41

Determine the molecular formula of a compound that has a molar mass of 264 g/mol and the empirical formula C₃H₄O₃.

A)CHO
B)CH_1.33O
C)C₉H₁₂O₉
D)C₆H₈O₆
E)C₃H₄O₃

Question 42

A compound is analyzed and found to contain 0.279 g C,0.0469 g H,and 0.124 g O.Its molecular mass is 116 g/mol.What is its molecular formula?

A)C₅H₈O₃
B)C₃H₆O
C)C₆H₁₂O₂
D)CH₆O₂
E)C₂H₁₂O₄

Question 43

A compound is composed of 74.0% C,8.70% H,and 17.3% N.Its molar mass is 162 g/mol.What is its molecular formula?

A)C₉H₁₂N₃
B)C₇₄H₉N₁₇
C)C₆H₈N
D)C₅H₇N
E)C₁₀H₁₄N₂

Question 44

A researcher finds that a compound is composed of 43.6% phosphorus and 56.4% oxygen.In a separate analysis,she finds that it has a molar mass of 142 g/mol.What is the molecular formula of the compound?

A)P₄O₁₀
B)P₃O₇
C)PO₂
D)PO
E)P₂O₅