Deck 10: Electron Transfer in Chemical Reactions

Question 1

What is the oxidation state of chromium in the compound K₂Cr₂O₇?

A)+4
B)+6
C)+7
D)-1

Answer 1

+6

Question 2

Identify the reduced species in the following chemical process (a lead storage battery): Pb + PbO₂ + 2H⁺ + 2HSO₄^- → 2PbSO₄ + 2H₂O .

A)PbO₂
B)Pb
C)H⁺
D)2HSO₄^-

Answer 2

PbO₂

Question 3

Which of the following is the most easily reduced?

A)(K⁺)
B)(Na⁺)
C)(Au⁺)
D)(^Hg2+)

Answer 3

(Au⁺)

Question 4

Identify the oxidizing agent in the following chemical process: Fe + Cu(NO₃)₂ → Fe(NO₃)₂ + Cu

A)Fe
B)Cu⁺²
C)NO₃^-
D)Cu

Question 5

Which atom in the compound KClO₃ has a negative oxidation state?

A)potassium
B)oxygen
C)both potassium and chlorine
D)both chlorine and oxygen

Question 6

What is the oxidation state of manganese in the compound KMnO₄?

A)+4
B)+2
C)+7
D)-4

Question 7

In the following reaction: Fe₂O₃ + 3CO → 2Fe + 3CO₂, which atom(s)has a more negative oxidation state on the product side than the reactant side?

A)iron
B)oxygen
C)carbon
D)carbon and oxygen

Question 8

Consult the EMF activity series and predict which of the following changes will occur if an iron nail is placed in an aqueous solution containing the (Sn²⁺)ion.

A)Nothing at all will happen (no reaction).
B)Tin will be further oxidized.
C)Iron will be reduced.
D)Iron will be oxidized.

Question 9

Consult the EMF activity series and predict which of the following changes will occur if an 24K gold ring (pure gold)is placed in an aqueous solution containing hydrochloric acid.

A)Nothing at all will happen (no reaction).
B)Hydrogen will be further oxidized.
C)Gold will be reduced.
D)Gold will be oxidized.

Question 10

What is reduction?

A)loss of electrons
B)increase in oxidation number
C)gain of electrons
D)two of the above

Question 11

Identify the reduced species in the following chemical process: Cu + 2AgCl → CuC1₂ + 2Ag

A)Ag
B)Ag+
C)Cl-
D)Cu

Question 12

What chemical process is happening at the anode of a fuel cell, which uses the following reaction to generate electricity: 2H₂ + O₂ → 2H₂O?

A)Hydrogen is being oxidized.
B)Oxygen is being oxidized.
C)Nothing at all is happening there.
D)Oxygen is being reduced.

Question 13

Identify the reducing agent in the following chemical process (a lead storage battery): Pb + PbO₂ + 2H⁺ + 2HSO₄^- → 2PbSO₄ + 2H₂O .

A)PbO₂
B)Pb
C)H⁺
D)2HSO₄^-

Question 14

Which atom in the compound K₂C₂O₄ has a positive oxidation state?

A)potassium
B)carbon
C)both potassium and carbon
D)both potassium and oxygen

Question 15

In the following reaction: Fe₂O₃ + 3CO → 2Fe + 3CO₂, which atom(s)has a more positive oxidation state on the product side than the reactant side?

A)iron
B)oxygen
C)carbon
D)carbon and iron

Question 16

Which of the following is most easily oxidized?

A)Ni
B)Pb
C)Li
D)Cr

Question 17

What is the oxidation state of the nitrogen atom in the compound NCl₃?

A)0
B)+3
C)+5
D)-3

Question 18

What is oxidation?

A)loss of electrons
B)increase in oxidation number
C)gain of electrons
D)two of the above

Question 19

Identify the reducing agent in the following chemical process: Cu + 2AgCl → CuC1₂ + 2Ag

A)Ag
B)Ag+
C)Cl-
D)Cu

Question 20

What is electricity?

A)flow of atoms
B)flow of protons
C)flow of neutrons
D)flow of electrons

Question 21

Which of the following is true about the following equation: Mg + O₂ → 2 MgO ?

A)Magnesium is oxidized.
B)The oxidation of magnesium in MgO is +2.
C)Oxygen is reduced.
D)All of the above are true.

Question 22

The overall charge of sodium dichromate is ________.

A)0
B)+1
C)+2
D)-2

Question 23

Halogens have often (but not always)________ as the main oxidation state.

A)+1
B)-1
C)+7
D)-3

Question 24

Which of the following elements may have +4 charge when it becomes an ion?

A)magnesium
B)aluminum
C)carbon
D)chlorine

Question 25

Which of the following elements may have a +3 charge when it becomes an ion?

A)magnesium
B)aluminum
C)carbon
D)chlorine

Question 26

What is the sum of the oxidation states in the following species H₂SbO₃^- ?

A)0
B)-1
C)+2
D)-2

Question 27

The charge of chlorine in the perchlorate ion is ________.

A)+8
B)+7
C)-1
D)+6

Question 28

In a chemical bond, which atom gets to own the shared electrons?

A)the larger element
B)the smaller element
C)the more electronegative element
D)the most electropositive element

Question 29

Which of the following is most easily oxidized?

A)Fe
B)Al
C)Cu
D)Au

Question 30

Which of the following elements may not have an oxidation number of -1?

A)chlorine
B)hydrogen
C)sodium
D)fluorine

Question 31

In which of the following is oxygen not at the -2 oxidation state?

A)water
B)methanol
C)hydrogen peroxide
D)carbon dioxide

Question 32

Which of the following is true for reaction Cu + ZnCl₂ → CuCl₂ + Zn ?

A)Cu is oxidized.
B)Cu is a reducing agent.
C)Zn⁺² is reduced.
D)All of the above statements are correct.

Question 33

The charge of sulfur in the sulfate ion is ________.

A)+6
B)+7
C)-2
D)+4

Question 34

In which compound is bromine in the +3 oxidation state?

A)NaBrO₂
B)NaBrO₃
C)NaBrO
D)NaBrO₄

Question 35

In the water molecule, which atom holds the shared electrons between hydrogen and oxygen?

A)oxygen
B)hydrogen
C)both are shared equally
D)One cannot say unless the state of water is known.

Question 36

The only element that is more electronegative than oxygen is ________.

A)chlorine
B)fluorine
C)nitrogen
D)sulfur

Question 37

Which of the following elements may have an oxidation number other than +2?

A)magnesium
B)calcium
C)barium
D)iron

Question 38

In which case is chlorine in its highest oxidation state?

A)sodium hypochlorite
B)sodium chloride
C)sodium perchlorate
D)sodium chlorate

Question 39

Which of the following has 18 electrons?

A)Ca²⁺
B)Cl⁺
C)S²⁺
D)Fe³⁺

Question 40

Which of the following elements may have an oxidation number of +1 or -1?

A)hydrogen
B)sodium
C)potassium
D)lithium

Question 41

The reactants in a dry cell are ________.

A)Cu⁺² and Zn
B)Zn⁺² and Cu
C)Zn and MnO₂
D)Zn⁺² and Al

Question 42

In a chemical bond the less electronegative element gets complete ownership of both the shared electrons.

Question 43

In which case is the greatest number of electrons transferred?

A)NaClO → NaClO₂
B)2 Mg + O₂ → 2 MgO
C)CuCl → CuCl₂
D)NaClO₂ → NaClO₄

Question 44

Which element is oxidized in the reaction 3 P + 5 HNO₃ + 2 H₂O → 5 NO + 3 H₃PO₄ ?

A)phosphorus
B)nitrogen
C)oxygen
D)No elements were either oxidized or reduced.

Question 45

In Mg⁺² the magnesium ion owns 10 electrons.

Question 46

Which of the following is true for reaction Zn + CuCl₂ → ZnCl₂ + Cu ?

A)The solution will turn blue.
B)The solution will turn from blue to light blue.
C)The gray zinc powder will disappear.
D)Both B and C are correct.

Question 47

The reducing agent is ________.

A)reduced in a redox equation
B)oxidized in a redox equation
C)reduced in an oxidation reaction
D)oxidized in a reduction reaction

Question 48

Which of the following reactions is an oxidation-reduction reaction?

A)NaOH + HCl → NaCl + H₂O
B)AgNO₃ + NaCl → AgCl + NaNO₃
C)CH₄ + 2 O₂ → CO₂ + 2 H₂O
D)CaO + CO₂ → CaCO₃

Question 49

Electricity is the flow of electrons.

Question 50

In which case is the least number of electrons transferred?

A)NaClO → NaClO₂
B)2 Mg + O₂ → 2 MgO
C)CuCl → CuCl₂
D)NaClO₂ → NaClO₄

Question 51

The oxidation state of oxygen gas is ________.

A)-4
B)+2
C)-2
D)0

Question 52

The reaction Zn + Cu⁺² → Zn⁺² + Cu is an example of a ________ battery.

A)zinc-copper
B)copper-zinc
C)copper-silver
D)copper-zinc--hydrogen

Question 53

The oxidizing agent is ________.

A)reduced in a redox equation
B)oxidized in a redox equation
C)reduced in an oxidation reaction
D)oxidized in a reduction reaction

Question 54

Which is the oxidizing agent in the reaction I₂ + 6 H₂O + 5 Cl₂ → 2HIO₃ + 10 HCl ?

A)I₂
B)H₂O
C)Cl₂
D)the oxygen in water

Question 55

In S^-2 the sulfur anion owns 16 electrons.

Question 56

When drawing dot structures, lone pairs of electrons are assigned completely to the atom on which they are drawn on the dot diagram.

Question 57

Which of the following reactions is not an oxidation-reduction reaction?

A)2 Na + H₂O → 2 NaOH + H₂
B)Mg + 2 HCl → MgCl₂ + H₂
C)CH₄ + 2 O₂ → CO₂ + 2 H₂O
D)CaO + CO₂ → CaCO₃

Question 58

The equation for rust formation is ________.

A)4 Fe + 3 O₂ + 2 H₂O → 2 Fe₂O₃ + H₂O
B)2 Fe + O₂ → 2 FeO
C)MnO₂ + 2 Fe → Mn + 2 FeO
D)CuO + Fe → Cu + FeO

Question 59

In a chemical reaction the easiest electrons to be transferred are the core electrons (also called inner shell electrons).

Question 60

In the reaction H₂O + CO₂ → H₂CO₃, which element was oxidized?

A)carbon
B)oxygen
C)hydrogen
D)None of the elements was oxidized.

Question 61

Assign the oxidation state of:
a)barium, in BaCl₂
b)sodium, in Na₂O
c)selenium, in H₂SeO₃
d)aluminum, in Al₂O₃

Question 62

The oxidation state of non-metals is almost always a negative number.

Question 63

The lowest oxidation state sulfur can have is in the sulfite form.

Question 64

Assign the oxidation state of:
a)each rhenium, in Re₂O₇
b)zirconium, in ZrCl₄
c)sulfur in Na₂S₂O₃
d)iodine in KIO₃

Question 65

Corrosion of a ship's hull can be inhibited if another metal that is more active is attached to the hull.

Question 66

The oxidation state of metals is almost always a positive number.

Question 67

A reducing agent is itself oxidized.

Question 68

The overall charge of calcium sulfate is -2.

Question 69

Assign oxidation states to each of the atoms in the following chemical species:
a)SiO₂
b)NO^-
c)TlCl
d)V₂O₅

Question 70

All four halogens, F, Cl, Br and I, are diatomic in their free state.

Question 71

Refer to these reactions to answer the questions below.
(a)Ba(OH)₂ + H₂SO₄ → 2H₂O + BaSO₄
(b) NaOH + HCl → NaCl + H₂O
(c) 2H₂ + O₂ → 2H₂O
(d) C₂H₆O + 3O₂ → 2CO₂ + 3H₂O
For each reaction above that can be classified as an electron transfer reaction, state which element(s)gain, and which element(s)lose, electrons.

Question 72

A spontaneous electrochemical cell is called a galvanic cell.

Question 73

The only tetraatomic element is sulfur.

Question 74

The cathode is the electrode where oxidation occurs.

Question 75

More active metals lose electrons to ions of less active metals.

Question 76

The highest oxidation state sulfur can have is in the sulfate form.

Question 77

Refer to these reactions to answer the questions below.
(a)Ba(OH)₂ + H₂SO₄ → 2H₂O + BaSO₄
(b) NaOH + HCl → NaCl + H₂O
(c) 2H₂ + O₂ → 2H₂O
(d) C₂H₆O + 3O₂ → 2CO₂ + 3H₂O
Which of the reactions above are examples of electron transfer reactions?

Question 78

The oxygen anion always has the charge of -2.

Question 79

Ca²⁺, K⁺ and Cl^- have the same number of electrons.

Question 80

The sum of the oxidation states of all atoms in a formula must add up to the overall charge of the formula.