Understanding Redox Half Reactions

What is the primary purpose of a redox half reaction?

• To balance chemical equations

• To show the full story of oxidation and reduction

• To determine the pH of a solution

• To calculate reaction rates

In the reaction between sodium and chlorine, what happens to the oxidation state of sodium?

• It increases from 0 to +1

• It remains the same

• It decreases from 0 to -1

• It decreases from +1 to 0

What indicates that sodium is being oxidized in its half reaction?

• Sodium gains electrons

• Electrons are on the product side

• Sodium forms a negative ion

• Electrons are on the reactant side

In the sodium-chlorine reaction, what is the role of chlorine?

• It is oxidized

• It remains unchanged

• It acts as a catalyst

• It is reduced

What is the oxidation state of aluminum in its elemental form?

• +3

• 0

• +1

• -2

In the reaction with copper sulfate, what happens to the oxidation state of copper?

• It increases from 0 to +2

• It decreases from +2 to 0

• It remains at +2

• It decreases from +3 to 0

What must aluminum do to change from an oxidation state of 0 to +3?

• Lose three electrons

• Lose one electron

• Gain one electron

• Gain three electrons

In the aluminum-copper reaction, what indicates that copper is being reduced?

• Copper gains electrons

• Copper loses electrons

• Copper forms a positive ion

• Copper remains unchanged

What is the oxidation state of copper in copper sulfate before the reaction?

• -1

• 0

• +1

• +2

Which of the following is true about the electrons in a reduction half reaction?

• They appear on the reactant side

• They are not present

• They appear on the product side

• They are balanced with protons