8 original questions from New Regents. The worksheet, answer key, and browser practice are free.
Oxidation and Reduction 4 questions
Oxidation and Reduction
New Regents original practice • Name: ____________________ Date: __________ Show your work for written answers.
Oxidation is loss of electrons. Reduction is gain of electrons. In a balanced overall redox reaction, the electrons lost equal the electrons gained.
Question 1
Which half reaction shows oxidation?
- Zn → Zn²⁺ + 2e⁻
- Cu²⁺ + 2e⁻ → Cu
- Ag⁺ + e⁻ → Ag
- Fe³⁺ + e⁻ → Fe²⁺
Question 2
Explain how you know Cu²⁺ is reduced when it becomes Cu.
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Question 3
How many electrons are lost when three Zn atoms become three Zn²⁺ ions in the model?
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Question 4
Where do electrons appear in a reduction half reaction?
- On the reactant side
- On the product side
- On both sides in equal number
- Only in the name of the substance
Combining Half Reactions 4 questions
Combining Half Reactions
Use the information below to answer the questions.
A reaction model pairs Zn → Zn2+ + 2e- with Ag+ + e- → Ag. Combine the halves so the transferred electrons cancel.
| Half reaction | Electrons per atom or ion |
|---|---|
| Zinc half reaction | 2 released per Zn |
| Silver half reaction | 1 consumed per Ag+ |
Question 5
How many Ag⁺ ions can be reduced by the electrons from one Zn atom?
- 1
- 2
- 3
- 4
Question 6
Write the overall equation for the transfer. Show why no free electrons appear in the final equation.
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Question 7
Which substance is oxidized in the overall equation?
- Zn
- Ag⁺
- Zn²⁺
- Ag
Question 8
Use the coefficients to show that total charge is the same before and after the overall reaction.
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