Redox Reactions 1

An increase in oxidation number.

• more acidic

• reduction

• less basic

• oxidation

Which of the following unbalanced equations represents oxidation?

• C + H2 → CH₄

• Fe³⁺ → Fe²⁺

• Cl₂ → 2Cl^-

• Zn → Zn²⁺

If in a reaction, copper is reduced; its number of electrons has:

• Increased
• Decreased
• Remained Constant
• Varies Randomly

Which of the following cannot occur during oxidation?

• Gain of oxygen

• Donation of electrons

• Loss of hydrogen

• Decrease in oxidation number

The sum of the oxidation numbers in SCN^- is equivalent to

• 0

• -1

• +1

• +3

Which of the following half reactions correctly represents a reduction half reaction?

• Fe →Fe²⁺ + 2e^-
• Pb⁴⁺ + 2e^- →Pb²⁺
• 2O^-2 →O₂ + 4e^-
• Fe + 3e^- →Fe³⁺

In the reaction Zn + 2HCl --> ZnCl₂ + H₂

which element, if any, is oxidized?

• Zinc

• Hydrogen

• Chlorine

• None

What is oxidation number of Cr in Cr₂O_7^2-?

• -2
• +2
• +6
• +12

What is oxidation number of H in CaH₂?

• +1
• -1
• 0
• +2

The following chemical equation represents the extraction of silicon from quartz using coke.

SiO₂ + C → Si + CO₂

What is the change in oxidation number of silicon?

• +2 to 0

• +4 to 0

• 0 to +2

• 0 to +4