Stoichiometry, Empirical & Molecular Formula (MC)

Question 1

Compound – Molar Mass (g)

Na₂O – 62.0

MgO – 40.3

K₂O – 94.2

CaO – 56.1

According to the information in the table above, a 1.00g sample of which of the following contains the greatest mass of oxygen?

a. Na₂O
b. MgO
c. K₂O
d. CaO

Answer 1

B

Question 2

Which of the following could be the identity of a white crystalline solid that exhibits the following properties?

• It melts at 320ºC
• It does not conduct electricity as a solid
• It conducts electricity in an aqueous solution

a. C₆H₁₂O₆(s)
b. NaOH(s)
c. SiO₂(s)
d. Cu(s)

Answer 2

B

Question 3

MnO₄^- + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O

In the reaction represented above, the number of MnO₄^- ions that react must be equal to which of the following?

a. One-fifth the number of Fe²⁺ ions that are consumed
b. Eight times the number of H⁺ ions that are consumed
c. Five times the number of Fe³⁺ ions that are produced
d. One-half the number of H₂O molecules that are produced

Answer 3

A

Question 4

C₃H₈(g) + 4Cl₂(g) → C₃H₄Cl₄(g) + 4HCl(g)

A 6.0 mol sample of C₃H₈(g) and a 20. mol sample of Cl₂(g) are placed in a previously evacuated vessel, where they react according to the equasion above. After one of the reactants has been totally consumed, how many moles of HCl(g) have been produced?

a. 4.0 mol
b. 8.0 mol
c. 20. mol
d. 24 mol

Answer 4

C

Question 5

Which of the following particulate diagrams best shows the formation of water vapor from hydrogen gas and oxygen gas in a rigid container at 125ºC?

Answer 5

C

Question 6

The mass percent of carbon in pure glucose, C₆H₁₂O₆, is 40.0 percent. A chemist analyzes an impure sample of glucose and determines that the mass percent of carbon is 38.2 percent. Which of the following impurities could account for the low mass percent of carbon in the sample?

a. Water, H₂O
b. Ribose, C₅H₁₀O₅
c. Fructose, C₆H₁₂O₆, an isomer of glucose
d. Sucrose, C₁₂H₂₂O₁₁

Answer 6

A

Question 7

The figure above represents three sealed 1.0 L vessels, each containing a different inert gas at 298K. The pressure of Ar in the first vessel is 2.0 atm. The ratio of the numbers of Ar, Ne, and He atoms in the vessels is 2:1:6, respectively. After all the gases are combined in a previously evacuated 2.0 L vessel, what is the total pressure of all the gases at 298K?

a. 3.0 atm
b. 4.5 atm
c. 9.0 atm
d. 18 atm

Answer 7

B

Question 8

Ag⁺(aq) + Cl^-(aq) ⇒ AgCl(s)

A student mixes dilute AgNO₃(aq) with excess NaCl(aq) to form AgCl(s), as represented by the net ionic equation above. Which of the diagrams below best represents the ions that are present in significant concentrations in the solution? (K_sp for AgCl is 1.8 x 10^-10

Answer 8

C

Question 9

PCl₅(g) ⇔ PCl₃(g) + Cl₂(g)

PCl₅(g) decomposes into PCl₃(g) and Cl₂(g) according to the equation above. A pure sample of PCl₅(g) is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl₅(g) is 1.00 atm. The temperature is held constant until the PCl₅(g) reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system.

If the decomposition reaction were to go to completion, the total pressure in the container will be

a. 1.4 atm
b. 2.0 atm
c. 2.8 atm
d. 3.0 atm

Answer 9

B

Question 10

K(s) + ½Cl₂(g) ⇒ KCl(s)

∆Hº = -437 kJ/mol_rxn

The elements K and Cl react directly to form the compound KCl according to the equation above. Refer to the information in the table below to answer the question that follows.

What remains in the reaction vessel after equal masses of K(s) and Cl₂(g) have reacted until either one or both of the reactants have been completely consumed?

a. KCl only
b. KCl and K only
c. KCl and Cl₂ only
d. KCl, K and Cl

Answer 10

C

Question 11

Beaker X and beaker Y each contain 1.0 L of solution, as shown above. A student combines the solutions by pouring them into a larger, previously empty beaker Z and observes the formation of a white precipitate. Assuming that volumes are additive, which of the following sets of solutions could be represented by the diagram above?

a. Beaker X: 2.0 M AgNO₃ / Beaker Y: 2.0 M MgCl₂ / Beaker Z: 4.0 M Mg(NO₃)₂ and AgCl(s)
b. Beaker X: 2.0 M AgNO₃ / Beaker Y: 2.0 M MgCl₂ / Beaker Z: 2.0 M Mg(NO₃)₂ and AgCl(s)
c. Beaker X: 2.0 M AgNO₃ / Beaker Y: 1.0 M MgCl₂ / Beaker Z: 1.0 M Mg(NO₃)₂ and AgCl(s)
d. Beaker X: 2.0 M AgNO₃ / Beaker Y: 1.0 M MgCl₂ / Beaker Z: 0.50 M Mg(NO₃)₂ and AgCl(s)

Answer 11

D

Question 12

Contains an element in a +1 oxidation state

a. CO₂
b. PbO₂
c. CaO
d. N₂O₅
e. Cu₂O

Answer 12

E

Question 13

The reaction between a Brønsted-Lowry acid and a Brønsted-Lowry base

a. 2C₆H₆(l) + 15O₂(g) ⇒ 12CO₂(g) + 6H₂O(l)
b. C₂H₃O₂^-(aq) + H₃O⁺(aq) ⇒ HC₂H₃O₂(aq) + H₂O(l)
c. 4H⁺(aq) + 4Co²⁺(aq) + O₂(g) + 24 NH₃(aq) ⇒ 4Co(NH₃)₆³⁺(aq) + 2H₂O(l)
d. CaCO₃(s) ⇒ CaO(s) + CO₂(g)
e. 2H₂O₂(l) ⇒ O₂(g) + 2H₂O(l)

Answer 13

B

Question 14

The reaction in which a single species is both oxidized and reduced

a. 2C6H6(l) + 15O2(g) ⇒ 12CO2(g) + 6H2O(l)
b. C2H3O2-(aq) + H3O+(aq) ⇒ HC2H3O2(aq) + H2O(l)
c. 4H+(aq) + 4Co2+(aq) + O2(g) + 24 NH3(aq) ⇒ 4Co(NH3)63+(aq) + 2H2O(l)
d. CaCO3(s) ⇒ CaO(s) + CO2(g)
e. 2H2O2(l) ⇒ O2(g) + 2H2O(l)

Answer 14

E

Question 15

Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the following elements combine with atoms of F in the same ratio?

a. Li
b. Ba
c. Al
d. Cl
e. Ne

Answer 15

B

Question 16

C₃H₈(g) + 5O₂(g) ⇒ 3CO₂(g) + 4H₂O(l)

In the reaction represented above, what is the total number of moles of reactants consumed when 1.00 mole of CO₂(g) is produced?

a. 0.33 mol
b. 1.33 mol
c. 1.50 mol
d. 2.00 mol
e. 6.00 mol

Answer 16

D

Question 17

H₂ +F₂ ⇒ 2HF

In the reaction represented above, what mass of HF is produced by the reaction of 3.0 x 10²³ molecules of H₂ with excess F₂? (Assume the reaction goes to completion).

a. 1.0 g
b. 4.0 g
c. 10. g
d. 20. g
e. 40. g

Answer 17

D

Question 18

…LiHCO₃(aq) + …H₂SO₄(aq) ⇒ …Li₂SO₄(aq) + …H₂O(l) + …CO₂(g)

When the equation above is balanced and the coefficients are reduced to lowest whole number terms, what is the coefficient of H₂O(l)?

a. 1
b. 2
c. 3
d. 4
e. 5

Answer 18

B

Question 19

When a 3.22 g sample of an unknown hydrate of sodium sulfate, Na₂SO₄•xH₂O(s), is heated, H₂O (molar mass 18 g) is driven off. The mass of the anhydrous Na₂SO₄(s) (molar mass 142 g) that remains is 1.42 g. The value of x in the hydrate is

a. 0.013
b. 1.8
c. 6.0
d. 10.
e. 20.

Answer 19

D

Question 20

What is the empirical formula of an oxide of chromium that is 48 percent oxygen by mass?

a. CrO
b. CrO₂
c. CrO₃
d. Cr₂O
e. Cr₂O₃

Answer 20

C

Question 21

2MnO₄^-(aq) + 5C₂O₄^2-(aq) + 16H⁺(aq) ⇒ 2Mn²⁺(aq) + 10CO₂(g) + 8H₂O(l)

Permanganate and oxalate ions react in an acidified solution according to the balanced equation above. How many moles of CO₂(g) are produced when 20. mL of acidified 0.20 M KMnO₄ solution is added to 50. mL of 0.10 M Na₂C₂O₄ solution?

a. 0.0040 mol
b. 0.0050 mol
c. 0.0090 mol
d. 0.010 mol
e. 0.020 mol

Answer 21

D

Question 22

Which of the following is NOT an acepted name for the formula given?

a. CH₃OH .. methanol
b. CuO .. copper (I) oxide
c. FeCl₃ .. iron (III) chloride
d. H₂SO₄ .. sulfuric acid
e. SrCO₃ .. strontium carbonate

Answer 22

B

Question 23

A student prepares a solution by dissolving 60.00 g of glucose (molar mass 180.2 g mol^-1) in enough distilled water to make 250.0 mL of solution. The molarity of the solution should be reported as

a. 12.01 M
b. 12.0 M
c. 1.332 M
d. 1.33 M
e. 1.3 M

Answer 23

C

Question 24

In 1.00 mol of potassium zirconium sulfate trihydrate, K₄Zr(SO₄)₃•3H₂O, there are

a. 3 x 6.02 x 10²³ hydrogen atoms
b. 6.02 x 10²³ sulfur atoms
c. 4 x 6.02 x 10²³ potassium atoms
d. 4 moles of oxygen atoms
e. 4 moles of zirconium atoms

Answer 24

C

Question 25

What is the maximum number of moles of Al₂O₃ that can be produced by the reaction of 0.40 mol of Al with 0.40 mol of O₂?

a. 0.10 mol
b. 0.20 mol
c. 0.27 mol
d. 0.33 mol
e. 0.40 mol

Answer 25

B

Question 26

…C₃H₈(g) + …O₂(g) ⇒ …H₂O(g) + …CO₂(g)

When the equation for the reaction represented above is balanced and all coefficients are reduced to the lowest whole-number terms, the coefficient for O₂(g) is

a. 1
b. 2
c. 3
d. 5
e. 6

Answer 26

D

Question 27

…Zn(s) + …H⁺(aq) + …NO₃^-(aq) ⇒ …Zn²⁺(aq) + …NH₄⁺(aq) + …H₂O(l)

When the equation above is balanced and all coefficients are reduced to lowest whole number terms, the coefficient for Zn(s) is

a. 2
b. 4
c. 6
d. 10
e. 14

Answer 27

B

Question 28

A sample of a compound contains 3.21 g of sulfur and 11.4 g of fluorine. Which of the following represents the empirical formula of the compound?

a. SF₂
b. SF₃
c. SF₄
d. SF₅
e. SF₆

Answer 28

E

Question 29

A compound contains 30. percent sulfur and 70. percent fluorine by mass. The empirical formula of the compound is

a. SF
b. SF₂
c. SF₄
d. SF₆
e. S₂F

Answer 29

C

Question 30

If 0.40 mol of H₂ and 0.15 mol of O₂ were to react as completly as possible to produce H₂O, what mass of reactant would remain?

a. 0.20 g of H₂
b. 0.40 g of H₂
c. 3.2 g of O₂
d. 4.0 g of O₂
e. 4.4 g of O₂

Answer 30

A

Question 31

…Ca₃(PO₄)₂(s) + …H₃PO₄(l) ⇒ …Ca(H₂PO₄)₂(s)

When the equation above is balanced and all coefficients are reduced to lowest whole-number terms, what is the coefficient of H₃PO₄(l)?

a. 1
b. 2
c. 3
d. 4
e. 5

Answer 31

D

Question 32

How many carbon atoms are contained in 2.8 g of C₂H₄?

a. 1.2 x 10²³
b. 3.0 x 10²³
c. 6.0 x 10²³
d. 1.2 x 10²⁴
e. 6.0 x 10²⁴

Answer 32

A

Question 33

A student mixes equal volumes of 1.0 M solutions of tin (II) chloride and copper (II) sulfate and observes that no precipitate forms. Then the student mixes equal volumes of 1.0 M solutions of zinc (II) sulfate and tin (II) fluoride and observes the formation of a precipitate. The formula of the precipitate must be

a. SnF₂
b. SnSO₄
c. Sn(SO₄)₂
d. ZnF
e. ZnF₂

Answer 33

E

Question 34

In the labratory, H₂(g) can be produced by adding which of the following ton 1 M HCl(aq)?

I. 1 M NH₃(aq)

II. Zn(s)

III. NaHCO₃(s)

a. I only
b. II only
c. III only
d. I and II only
e. I, II, and III

Answer 34

B

Question 35

Propane gas, C₃H₈, burns in excess oxygen gas. When the equation for this reaction is correctly balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O₂ is

a. 4
b. 5
c. 7
d. 10
e. 22

Answer 35

B

Question 36

A 1.0 L sample of an aqueous solution contains 0.10 mol of NaCl and 0.10 mol of CaCl₂. What is the minimum number of moles of AgNO₃ that must be added to the solution in order to precipitate all of the Cl^- as AgCl(s)? (Assume that AgCl is insoluble.)

a. 0.10 mol
b. 0.20 mol
c. 0.30 mol
d. 0.40 mol
e. 0.60 mol

Answer 36

C

Question 37

What is the final concentration of barium ions, [Ba²⁺], in solution when 100. mL of 0.10 M BaCl₂(aq) is mixed with 100. mL of 0.050 M H₂SO₄(aq)?

a. 0.00 M
b. 0.012 M
c. 0.025 M
d. 0.075 M

Answer 37

C

Question 38

In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00?

a. CrO₃
b. CrO₂
c. CrO
d. Cr₂O
e. Cr₂O₃

Answer 38

B

Question 39

If 87 grams of K₂SO₄ (molar mass 174 grams) is dissolved in enough water to make 250 milliliters of solution, what are the concentrations of the potassium and the sulfate ions?

a. [K⁺] = 0.020 M / [SO₄^2-] = 0.020 M
b. [K⁺] = 1.0 M / [SO₄^2-] = 2.0 M
c. [K⁺] = 2.0 M / [SO₄^2-] = 1.0 M
d. [K⁺] = 2.0 M / [SO₄^2-] = 2.0 M
e. [K⁺] = 4.0 M / [SO₄^2-] = 2.0 M

Answer 39

E

Question 40

It is suggested that SO₂ (molar mass 64 grams), which contributes to acid rain, could be removed from a stream of waste gases by bubbling the gases through 0.25-molar KOH, thereby producing K₂SO₃. What is the maximum mass of SO₂ that could be removed by 1,000. liters of the KOH solution?

a. 4.0 kg
b. 8.0 kg
c. 16 kg
d. 20. kg
e. 40. kg

Answer 40

B

Question 41

When a 1.00-gram sample of limestone was dissolved in acid, 0.38 gram of CO₂ was generated. If the rock contained no carbonate other than CaCO₃, what was the percent of CaCO₃ by mass in the limestone?

a. 17%
b. 51%
c. 64%
d. 86%
e. 100%

Answer 41

D

Question 42

…Fe(OH)₂ + …O₂ + …H₂O ⇒ …Fe(OH)₃

If 1 mole of O₂ oxidizes Fe(OH)₂ according to the reaction represented above, how many moles of Fe(OH)₃ can be formed?

a. 2
b. 3
c. 4
d. 5
e. 6

Answer 42

C