Deck 5: Stoichiometry and the Mole

Question 1

Consider the equation, 2Na + Cl₂ → 2NaCl. This equation shows that 6.022 × 10²³ units of NaCl can be produced when one mole of Cl₂ and two moles of Na react.

Answer 1

False

Question 2

One gram of carbon-12 contains one mole of carbon atoms.

Answer 2

False

Question 3

A mole of a substance has the same mass in grams as one unit (atom or molecules) has in atomic mass units.

Answer 3

True

Question 4

The reactant gives the least amount of a particular product in a chemical reaction can be called the limiting reagent for that product.

Question 5

Consider the chemical reaction, 2Al + 3Cl₂ $\rightarrow$ 2AlCl₃. Here, 56 g of Al can produce 276.54 g of AlCl₃ (Molar masses: Al = 26.98 g; Cl = 35.45 g).

Question 6

The relating of one chemical substance to another using a balanced chemical reaction is called _____.

A) computational chemistry
B) informatics
C) analytical chemistry
D) stoichiometry
E) HYPERLINK "http://en.wikipedia.org/wiki/Stereochemistry" stereochemistry

Question 7

If percent yield determined is greater than 90%, it indicates an error.

Question 8

When calculating the amount of product assuming that all the reactant reacts, we are calculating the actual yield.

Question 9

The percent yield of the various stages in a reaction is given below.
A→ Intermediary1 (percent yield = 70%) → Intermediary2 (percent yield = 80%) → B (Percent Yield = 90%). The overall percent yield of this reaction is 50.%.

Question 10

Mass quantities of one substance can be related to mass quantities using a balanced chemical equation.

Question 11

The numerical value of things in a mole is often called Avogadro's number.

Question 12

The percent yield can be calculated using the formula, percent yield =actual yield÷ theoretical yield × 100%.

Question 13

CH₄ + 2 O₂ → CO₂ + 2 H₂O. 50 g of CH₄ and 120 g of O₂ react with each other. The reactant O₂ is in excess here. (Molar masses: C = 12 g; H = 1 g; O = 16 g)

Question 14

Fe₂O₃ + Fe + 6 HCl → 3 FeCl₂ + 3 H₂O. This chemical equation is balanced in terms of moles.

Question 15

If the molar mass of HCl is 36.46, the mass of 15 mol of HCl is 546.9
g.

Question 16

How many molecules of oxygen should react with hydrogen molecules to form 14 molecules of water?

A) 3
B) 4
C) 6
D) 7
E) 8

Question 17

Consider the chemical reaction, 2Al + 3Cl₂ $\rightarrow$ 2AlCl₃. Here, 212.7 g of chlorine can produce a maximum of 266.66 g of AlCl₃ (Molar masses: Al = 26.98 g; Cl = 35.45 g).

Question 18

The molar mass of carbon is 12
g. This indicates that 12 × 6.022 × 10²³ atoms are present in one gram of carbon.

Question 19

Consider the reaction, N₂ + 3H₂ $\rightarrow$ 2NH₃. 15 g of NH₃ is formed from 18 g of N₂. The percent yield in this example is 83.33% (Molar masses: N = 14 g; H = 1.0 g).

Question 20

The theoretical yield of a reaction is 50 g and the actual yield is 40
g. The percent yield of this reaction is 80%.

Question 21

How many molecules are present in 3.16 mol of CaCl₂?

A) 3.16 × 10²³
B) 6.16 × 10²³
C) 3.16 × 10²⁴
D) 6.03 × 10²³
E) 1.90 × 10²⁴

Question 22

What is the mass of 3.56 mole of CuCl₂ if the molar mass of CuCl₂ is 134.45 g/mol?

A) 479
B) 478.642
C) 478.6
D) 478
E) 480

Question 23

How many kilograms of carbon-12 would contain 6.000 × 10²⁶ atoms?

A) 12.35
B) 1.65
C) 11.95
D) 10.65
E) 0.12

Question 24

One mole equals _____ things.

A) 1.6726 × 10²⁷
B) 6.022 × 10²³
C) 3.16 × 10²⁴
D) 2.303 × 10²⁴
E) 1.903 × 10²⁴

Question 25

Sixteen moles of aluminium (Al) react with twenty-four moles of chlorine. How many moles of AlCl₃ are obtained as a result of this reaction?

A) 12
B) 16
C) 20
D) 24
E) 28

Question 26

Consider the unbalanced chemical reaction Al + Cl₂ $\rightarrow$ AlCl₃. How many moles of AlCl₃ can be obtained from 360 grams of Cl₂? (Molar masses: Cl = 35.45 g/mol, Al = 26.98 g/mol)

A) 70.9
B) 400
C) 270
D) 130
E) 450 (these answers do not follow significant figures)

Question 27

What is the mass of 1 mole of diatomic hydrogen?

A) 2.6 g
B) 2.0158 g
C) 12 g
D) 2.9 g
E) 1.0079 g

Question 28

How many CO molecules are formed when one mole of CO₂ reacts with 1.000 mole of carbon?

A) 6.022 × 10²³
B) 6.022 × 10²⁴
C) 1.204 × 10²⁴
D) 3.022 × 10²³
E) 2.409 × 10²⁴

Question 29

One _____ refers to the number of things equal to the number of atoms in exactly 12 g of carbon-12.

A) quantum
B) mole
C) Faraday
D) Henry
E) carbon unit

Question 30

Consider the unbalanced equation H₂ + O₂ → H₂O. How many molecules of water is involved in the equation if it is interpreted in terms of moles?

A) 1.2044 × 10²⁴
B) 6.022 × 10²³
C) 1.2044 × 10²³
D) 6.022 × 10²⁴
E) 3.2 × 10²⁷

Question 31

Consider the chemical reaction. 2H₂ +O₂ → 2H₂O. How many water molecules can be formed from 15.0 g H₂ if O₂ is available abundantly (Molar mass of H₂ = 2.016 g)?

A) 4.48 × 10²³
B) 5.36 × 10²³
C) 1.67 × 10²³
D) 4.48 × 10²⁴
E) 5.36 × 10²⁴

Question 32

How many moles of oxygen would yield 120 moles of water molecules in the following chemical reaction? 2C₄H₁₀ + 13O₂ $\rightarrow$ 8CO₂ + 10H₂O

A) 78
B) 104
C) 160
D) 156
E) 130

Question 33

Consider the chemical reaction 2CuCl₂ + SO₂ + 2H₂O → 2CuCl + 2HCl + H₂SO₄. How many grams of water is required to produce 14.0 moles of sulphuric acid?

A) 14.0
B) 28.0
C) 144
D) 504
E) 505

Question 34

Fe₂O₃ (s) + 3SO₃ (g) $\rightarrow$ Fe₂(SO₄)₃. This equation explains the formation of iron(III) sulfate. How many molecules of Fe₂(SO₄)₃ are formed if 144 molecules of SO₃ gas is passed through a beaker containing iron(III) oxide?

A) 288
B) 144
C) 72
D) 24
E) 48

Question 35

How many moles of atoms can be found in 70 grams of carbon-12?

A) 0.5
B) 1
C) 60
D) 6
E) 5

Question 36

Consider the chemical equation, Pd + 2 CuCl₂ → 2 CuCl + PdCl₂. How many moles of CuCl₂ is needed to produce 1.6 moles of PdCl₂?

A) 0.8
B) 1
C) 1.2
D) 1.6
E) 3.2

Question 37

Avogadro's number refers to _____.

A) the numerical value of things in a mole
B) the total number of atoms in a kg of a compound
C) a ratio of the masses of reactants and the masses of all the products
D) the total number of neutrons in a molecule
E) the total number of protons in a compound

Question 38

Na + Cl₂ → NaCl. This is an unbalanced chemical equation showing the formation of NaCl. How many chlorine molecules are needed to form 252 molecules of NaCl?

A) 28
B) 42
C) 63
D) 126
E) 252

Question 39

Consider the chemical equation P₄ + 5O₂ $\rightarrow$ P₄O₁₀. How many moles of oxygen are needed to convert 4 moles of phosphorous to P₄O₁₀?

A) 4
B) 5
C) 10
D) 15
E) 20

Question 40

C₈H₁₈ + O₂ → CO₂ + H₂O. Balance this equation and identify the number H₂O molecules formed when 6 molecules of C₈H₁₈ react with 75 molecules of oxygen.

A) 54
B) 48
C) 36
D) 32
E) 18

Question 41

The percent yield for a reaction is estimated to be 70.0%. Calculate the actual yield if the theoretical yield is 105 g of product.

A) 52.5 g
B) 70 g
C) 73.5 g
D) 105 g
E) 102.5 g

Question 42

Which of the following can be used as a measure to compare the actual yield and theoretical yield?

A) Molar yield
B) Mass number
C) Limiting reagent
D) Percent yield
E) Nuclear mass

Question 43

Which of the following is an assumption made when calculating theoretical yield?

A) Chemical reaction is conducted in vacuum
B) All the reactant in a chemical reaction reacts with others.
C) Chemical reaction involves heating process
D) Room temperature is maintained throughout the reaction
E) Actual yield is more than the theoretical yield.

Question 44

Reactant that _____ is called the excess reagent.

A) gives the least amount of product
B) is available in excess
C) has the largest mass number
D) has the smallest mass number
E) has the smallest atomic number

Question 45

Consider the chemical reaction, H₂CO₃ → H₂O + CO₂. Here, the percent yield is calculated to be 60%. Calculate the amount of H₂CO₃ needed to produce 56.00 g CO₂ (Molar masses: H₂CO₃ = 62.03 g; H₂O = 18.015 g; CO₂ = 44.00 g).

A) 62.03 g
B) 93.045 g
C) 72.06 g
D) 131.58 g
E) 78.95 g

Question 46

Consider the chemical equation 2H₂ + O₂ →2H₂O. Which of the following is the limiting reagent when 18 g hydrogen reacts with 30 g oxygen? (Molar masses: H = 1.008 g; O = 16.00 g)

A) Hydrogen
B) Water
C) Oxygen
D) H⁺ ion
E) OH^- ion

Question 47

How many moles of HCl will be produced when 30.000g of H₂O are reacted according to the chemical equation 2AlCl₃ + 3H₂O $\rightarrow$ Al₂O₃ + 6HCl? (Molar masses: H₂O = 18.015 g; HCl = 36.46 g)

A) 72.92
B) 36.03
C) 121.43
D) 109.38
E) 145.84

Question 48

How many grams of C₂H₂ can be formed when one gram of carbon reacts with one gram of hydrogen according to the reaction 2C + H₂ $\rightarrow$ C₂H₂? (Molar masses: C = 12 g; H = 1 g)

A) 6.32
B) 1.08
C) 2.16
D) 4.08
E) 12.6

Question 49

Which of the following cannot be a valid percent yield value?

A) 0%
B) 30%
C) 60%
D) 90%
E) 120%

Question 50

The amount that is really produced in a reaction is called the _____.

A) molar yield
B) molar mass
C) percent yield
D) limiting reagent
E) actual yield

Question 51

How many molecules are present in 58 grams of CuCl₂ if the molar mass of copper is 63.55 g and molar mass of chlorine is 35.45 g?

A) 1.67
B) 2.64
C) 0.32
D) 0.43
E) 0.59

Question 52

How many grams of SO₃ can be produced from 15.00 grams of oxygen molecule when reactions takes place according to the following equation 2SO₂ + O₂ $\rightarrow$ 2SO₃? (Molar masses: S = 32.07 g; O = 16.00 g)

A) 75.07
B) 80.07
C) 64.00
D) 63.00
E) 150.13

Question 53

Consider the chemical equation, N₂ + 3H₂ $\rightarrow$ 2NH₃. How many grams of nitrogen are needed to produce 50.00 grams of ammonia? (Molar masses: N₂ = 28.013 g; NH₃ = 17.03 g)

A) 56.026
B) 41.12
C) 34.06
D) 51.09
E) 82.25

Question 54

In a chemical reaction, A and B reacts to form D. C is the intermediate product of this reaction. Percent yield of the reaction A+B→C is 50.% and percent yield of the reaction C→D is 90.%. How many moles of D can be produced when 14 moles of A and B react?

A) 5.6
B) 7
C) 19.6
D) 11.2
E) 39.2

Question 55

Consider the chemical equation, 2H₂+O₂ → 2H₂O (Molar masses: H₂ = 2.016 g; O₂ = 32 g; H₂O = 18.016 g). If the percent yield of this reaction is estimated to be only 90%, calculate the amount of water that can be produced from 90.00 g oxygen.

A) 91.2
B) 72.06
C) 202.66
D) 182.4
E) 36.03

Question 56

Which of the following is the conversion factor for AlCl₃ and HCl considering the following equation? 2AlCl₃ + 3H₂O $\rightarrow$ Al₂O₃ + 6HCl

A) 1/1
B) 1/3
C) 1/2
D) 1/4
E) 1/6

Question 57

Consider a chemical reaction that follows the equation NaHCO₃ + CH₃COOH → NaCH₃COO + CO₂ + H₂O. 80 g of NaHCO₃ and 65 g CH₃COOH is available for performing this reaction. Which of the following is considered to be in excess? (Molar masses: NaHCO₃ = 84 g; CH₃COOH = 60.05 g)

A) NaCH₃COO
B) NaHCO₃
C) CO₂
D) H₂O
E) CH₃COOH

Question 58

In a chemical reaction A and B reacts to become E. C and D are the intermediaries of this reaction. The percent yields of the reaction are given below. What is the overall percent yield? A+B→C (Percent yield=70%)
C→D (Percent yield=90%)
D→E(Percent yield=50%)

A) 210%
B) 50%
C) 90%
D) 70%
E) 31.5%

Question 59

A limiting reagent is _____.

A) the reactant that controls the atmospheric conditions limit
B) a catalyst used in chemical reaction
C) the reactant which gives the lesser amount of product in a chemical reaction
D) a negative catalyst that slows down chemical reactions
E) the reactant that behaves according to atmospheric conditions

Question 60

Consider the equation, 2Rb + MgCl₂ $\rightarrow$ Mg + 2RbCl. If 82.00 g of Rb are available, what is the amount of MgCl₂ needed? (Molar masses: Rb = 85.47 g; Mg = 24.3 g; Cl = 35.45 g)

A) 95.2
B) 85.47
C) 45.67
D) 82.47
E) 91.33

Question 61

Six grams of carbon-12 contain _____ atoms.

Question 62

Explain the concepts of theoretical yield and actual yield.

Question 63

Compare and contrast mole-mole calculation and mole-mass calculation.

Question 64

N₂ + 3H₂ $\rightarrow$ 2NH₃
A synthesis produces 50 g ammonia from 60 g N₂. What is the theoretical yield and the percent yield?

Question 65

What is mass-mass calculation?

Question 66

What is percent yield?

Question 67

Consider the equation, 2AlCl₃ + 3H₂O $\rightarrow$ Al₂O₃ + 6HCl. How many moles of Al₂Cl₃ can be produced from 1 kg of AlCl₃? Explain the answer.

Question 68

Avogadro's number refers to the _____.

Question 69

The molecular mass of CaCO₃ is _____ if the molar masses of Ca, C, and O are 40, 12, and 16 g/mol, respectively.

Question 70

When do you say a reactant is in excess? Explain with an example.

Question 71

How many moles would represent 1.5 × 10²⁶ molecules of oxygen? Explain your answer.

Question 72

_____ molecules of H₂O are formed when 16 molecules of hydrogen react with 8 molecules of oxygen.

Question 73

Explain mole-mass calculation with an example.

Question 74

What is stoichiometry? Why is it used?

Question 75

A(n) _____ is a number of things equal to the number of atoms in exactly 12 g of carbon-12.

Question 76

Consider the equation, 2 HYPERLINK "http://en.wikipedia.org/wiki/Sodium_chloride" \o "Sodium
chloride" NaCl + _{HYPERLINK "http://en.wikipedia.org/wiki/Sulfuric_acid" \o "Sulfuric acid"} H₂SO₄ → _{HYPERLINK "http://en.wikipedia.org/wiki/Sodium_sulfate" \o "Sodium
sulfate"} Na₂SO₄ + 2 HYPERLINK "http://en.wikipedia.org/wiki/Hydrochloric_acid" \o "Hydrochloric acid" HCl. Which reactant is the limiting reagent when 50.00 g NaCl and 60.00 g H₂SO₄ react? How much is in excess?

Question 77

Briefly explain the concept of a mole and molar mass.

Question 78

A + 3B → 2C. Interpret this chemical equation in terms of moles.

Question 79

Are all balanced equations conventional? Explain your answer.

Question 80

What is limiting reagent? Provide an example.