Science: Redox Reactions and Electrochemistry Worksheet

Question 1

Define oxidation and reduction in terms of electron transfer.

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons. In every redox reaction, one substance loses electrons while another substance gains them.

Question 2

In the reaction Zn + Cu2+ -> Zn2+ + Cu, identify which species is oxidized and which species is reduced.

Accepted Answer

Zinc is oxidized because it changes from Zn to Zn2+ by losing electrons. Copper ion, Cu2+, is reduced because it gains electrons and becomes Cu.

Question 3

Assign the oxidation number of each element in H2O.

Accepted Answer

In H2O, hydrogen has an oxidation number of +1 and oxygen has an oxidation number of -2. The total adds to 0 because water is a neutral compound.

Question 4

Assign the oxidation number of sulfur in SO4^2-.

Accepted Answer

Oxygen is usually -2, so four oxygens contribute a total of -8. The ion has an overall charge of -2, so sulfur must be +6 to make the total equal -2.

Question 5

Determine whether the following reaction is a redox reaction: 2Mg + O2 -> 2MgO. Explain your answer.

Accepted Answer

Yes, this is a redox reaction. Magnesium is oxidized because its oxidation number changes from 0 to +2, and oxygen is reduced because its oxidation number changes from 0 to -2.

Question 6

Write the oxidation half-reaction for magnesium in the reaction Mg -> Mg2+ + 2e-.

Accepted Answer

The oxidation half-reaction is Mg -> Mg2+ + 2e-. This shows that magnesium loses two electrons, so it is oxidized.

Question 7

Write the reduction half-reaction for chlorine in the reaction Cl2 + 2e- -> 2Cl-.

Accepted Answer

The reduction half-reaction is Cl2 + 2e- -> 2Cl-. This shows that chlorine gains electrons, so it is reduced.

Question 8

In a galvanic or voltaic cell, what is the function of the salt bridge?

Accepted Answer

The salt bridge allows ions to move between the half-cells so charge does not build up. This maintains electrical neutrality and allows the cell to continue operating.

Question 9

In an electrochemical cell, where does oxidation occur and where does reduction occur?

Accepted Answer

Oxidation occurs at the anode, and reduction occurs at the cathode. This is true for all electrochemical cells.

Question 10

Describe the direction of electron flow in a galvanic cell.

Accepted Answer

Electrons flow through the external circuit from the anode to the cathode. They move from the site of oxidation to the site of reduction.

Question 11

Explain why rusting of iron is considered a redox process.

Accepted Answer

Rusting is a redox process because iron atoms lose electrons and are oxidized, while oxygen gains electrons and is reduced. The reaction between iron, oxygen, and water forms iron oxides.

Question 12

A student says that the reducing agent in a reaction is the substance that gets reduced. Correct this statement and explain the role of a reducing agent.

Accepted Answer

The statement is incorrect. A reducing agent causes another substance to be reduced by donating electrons, and the reducing agent itself is oxidized in the process.

Science: Redox Reactions and Electrochemistry

Science: Redox Reactions and Electrochemistry

More Chemistry Worksheets

More Grade 9-12 Worksheets